Tuberous Sclerosis

Background

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder characterized by a variety of organ system changes. Its name is derived from the characteristic changes that occur in the brain, called tubers. Over time, these tuberous growths become hard and sclerotic and may calcify. Until recently, most of the proliferations and tumors associated with the disease were thought to be hamartomas. Recent molecular biological analysis has revealed that these are clonal processes and true neoplastic growths. The TSC1 and TSC2 genes behave as tumor suppressor genes. If a somatic mutation of the second allele occurs, abnormal cell growth and differentiation occur.

The current diagnostic criteria divide the disease into diagnostic categories based upon the combination of clinical and histological findings.

Definite TSC:Either 2 major features or 1 major feature and 2 minor features
Possible TSC: Either 1 major feature or 2 or more minor features

Major Features Minor Features

Facial angiofibromas or forehead plaque
Nontraumatic ungual or periungual fibroma
Hypomelanotic macules (more than 3)
Shagreen patch (connective tissue nevus)
Multiple renal nodular hamartomas
Cortical tuber*
Subependymal nodule
Subependymal giant cell astrocytoma
Cardiac rhabdomyoma, single or multiple
Lymphangiomyomatosis**
Renal angiomyolipoma** Multiple randomly distributed pits in dental enamel
Hamartomatous rectal polyps
Bone cysts
Cerebral white matter migration lines-may be diagnosed radiologically
Gingival fibromas
Nonrenal hamartomas
Retinal achromatic patch
Confetti skin lesions
Multiple renal cysts

*When cerebral cortical dysplasia and cerebral white matter migration tracts occur together, they should be counted as 1 rather than 2 features of TSC
**When both lymphangioleiomyomatosis and renal angiomyolipomas are present, other features of TSC should be present before a definitive diagnosis is assigned.

OUTLINE

Epidemiology

Disease Associations

Pathogenesis

Laboratory/Radiologic/Other Diagnostic Testing

Gross Appearance and Clinical Variants

Histopathological Features and Variants

Special Stains/Immunohistochemistry/Electron Microscopy

Differential Diagnosis

Prognosis

Treatment

Commonly Used Terms

Internet Links

EPIDEMIOLOGY CHARACTERIZATION

SYNONYMS Bourneville disease

INCIDENCE 1/8000

DISEASE ASSOCIATIONS CHARACTERIZATION

PARATHYROID HYPERPLASIA

Secondary Parathyroid Hyperplasia in Tuberous Sclerosis
Report of a Case With Large Eosinophilic Ganglion-Like Cells Similar to Those of Subependymal Giant Cell Astrocytoma, Tubers, and Atypical Angiomyolipoma
Howard L. Martin, M.D ; Edward Lee, M.D. ; Jorge Albores-Saavedra, M.D.

From the Division of Anatomic Pathology, Department of Pathology (H.L.M., J.A.-S.), University of Texas Southwestern Medical Center, Dallas, Texas; and the Department of Pathology (E.L.), Veterans Affairs Medical Center, Dallas, Texas, U.S.A.
Am J Surg Pathol 2002;26:260-265 Abstract quote
We report a case of secondary parathyroid hyperplasia in a 49-year-old man with tuberous sclerosis.

Two parathyroid glands had collections of large, eosinophilic ganglion-like endocrine cells that to our knowledge have not been previously described at this site. These cells are morphologically similar to those of subependymal giant cell astrocytoma, tubers, and atypical angiomyolipoma, all of which may arise in the setting of tuberous sclerosis. These large, eosinophilic ganglion-like cells found in different affected organs appear to be distinctive of tuberous sclerosis.

We suggest these large eosinophilic cells arise from a common stem cell precursor that acquires variable phenotypes according to alterations in the cellular microenvironment.

PATHOGENESIS-TUBEROUS SCLEROSIS (TSC)

CHARACTERIZATION TSC1 TSC2

Chromosome location 9q34 16p13

Mutational spectrum, %

Large deletion and rearrangement
2 17

Small deletion and insertion
56 33

Nonsense
37 20

Splice
5 6

Misense
0 23

Number of exons 139 250

mRNA size in KB 8.6 5.5

Protein product length 1164 1784

Protein product name Hamartin Tuberin

Protein function Associates physically with tuberin Negative growth regulator
Putatative GTPase activating protein for rap1 and rab5

ADDITIONAL PATHOGENETIC MECHANISMS CHARACTERIZATION

GENERAL

Tuberous sclerosis-associated lesions of the kidney, brain, and skin are angiogenic neoplasms

Jack L. Arbiser, MD, PhD
Daniel Brat, MD, PhD
Steve Hunter, MD, etal.

Atlanta, Georgia, New York, New York, Philadelphia, Pennsylvania, and Tucson, Arizona

J Am Acad Dermatol 2002;46:376-80 Abstract quote

Background: Tuberous sclerosis is an autosomal dominant condition characterized by the development of benign neoplasms of the brain, kidney, and skin. Progressive growth and malignant transformation of brain and kidney lesions constitute the major cause of morbidity and mortality in adults with tuberous sclerosis. In addition, growth of skin lesions may be disfiguring to patients.

Objective: The purpose of this study was to determine whether benign tumors in patients with tuberous sclerosis are angiogenic.

Methods: Brain, kidney, and skin tumors from patients with tuberous sclerosis were stained with CD31, a specific marker of vascular endothelium. In addition, we used Northern blot analysis to demonstrate that renal angiomyolipoma cells express the potent angiogenesis stimulator vascular endothelial growth factor (VEGF).

Results: Brain, kidney, and skin neoplasms from patients with tuberous sclerosis are highly angiogenic. Renal angiomyolipoma cells produce the potent angiogenic factor VEGF.

Conclusion: Benign neoplasms of patients with tuberous sclerosis are highly vascular. Our results provide a rationale for antiangiogenic therapy in the treatment and prevention of tuberous sclerosis-associated neoplasms.

TUBERIN

Loss of tuberin, the tuberous-sclerosis-complex-2 gene product is associated with angiogenesis

Phuong-Anh Nguyen-Vu1, Ingrid Fackler1, Adelheid Rust2, Jeffrey E. DeClue3, Christian A. Sander1, Matthias Volkenandt1, Michael Flaig1, Raymond S. Yeung4 and Ralf Wienecke1 1

Department of Dermatology, Ludwig-Maximilians-University Munich, Munich, Germany, 2 Department of Dermatology, Mayo Clinic and Foundation, Rochester, Minnesota, USA, 3 National Cancer Institute, Laboratory of Cellular Oncology, Bethesda, Maryland, USA, 4 Department of Surgery & Division of Medical Genetics, University of Washington, Seattle, Washington, USA

Journal of Cutaneous Pathology 2001;28 (9), 470-475

Background: Tuberous sclerosis complex (TSC) is an autosomal dominantly inherited disorder associated with an alteration of the TSC2 tumor suppressor gene which encodes for the protein product tuberin. The disease is characterized by the development of hamartomas, e.g. cutaneous angiofibromas which consist of vascular cells, interstitial cells, and normal components of the skin. The Eker rat model, an animal model of inherited cancer, has been shown to carry a mutation of TSC2.

Methods: Immunohistochemical analyses of human angiofibromas were performed using antibodies directed against tuberin and angiogenic growth factors. Proliferation of human dermal microvascular endothelial cells (HDMEC) was determined after incubation with the supernatants of TSC2 (+/+) and TSC2 (-/-) rat embryonic fibroblasts (REF) that were derived from the Eker strain.

Results: Loss of the expression of tuberin was observed in the interstitial cells of 13 of 39 angiofibromas. The expression of tuberin was retained in the vascular cells. In all analyzed angiofibromas, the angiogenic factors bFGF, PD-ECGF, VEGF and angiogenin were detected in the interstitial cells and/or vascular cells. Expression of PDGF-B and TGF-b1 was weak. Tissue culture supernatants from TSC2 (-/-) REF stimulated the growth of HDMEC significantly more than supernatants from TSC2 (+/+) REF.

Conclusion: A functional loss of tuberin may stimulate vascular growth.

Reduction of expression of tuberin, the tuberous-sclerosis-complex-gene-2 product in tuberous sclerosis complex associated connective tissue nevi and sporadic squamous and basal cell carcinomas.

Wienecke R, Klemm E, Karparti S, Swanson NA, Green AJ, DeClue JE.

Department of Dermatology and Allergology, Ludwig-Maximilians-University Munich, Munich, Germany, National Institutes of Health, National Cancer Institute, Laboratory of Cellular Oncology, Bethesda, Maryland, USA, Department of Dermatology, Semmelweis University, Budapest, Hungary, Oregon Health Sciences University, Department of Dermatology, Portland, Oregon, USA, Department of Medical Genetics and Conway Institute, University College Dublin, Ireland
J Cutan Pathol 2002 May;29(5):287-290 Abstract quote
Background: Patients affected with tuberous sclerosis complex (TSC) are prone to the development of multiple benign tumors of the skin and other organs. Tuberin, the protein product of the tuberous-sclerosis-complex-2 tumor suppressor gene (TSC2) has been shown to inhibit cell proliferation. In TSC associated kidney tumors and sporadic brain tumors the loss/reduction of tuberin has been shown.

Methods: Specimens of nine squamous cell carcinomas (SCC) and five basal cell carcinomas (BCC) from patients without TSC and six biopsies of connective tissue nevi (CTN) of patients with TSC were obtained. Specimens were analyzed by immunoblotting for the expression of tuberin. Results: Absent or reduced levels of tuberin were detected in the dermal parts of three of six shagreen patches, two of five BCC, and four of nine SCC.

Conclusions: In tumors/hamartomas of patients with TSC the complete loss of TSC2 and tuberin is a mechanism which could be shown for CTN, thereby excluding the possibility of haploinsufficiency of TSC2. In a substantial number of cutaneous BCC and SCC the loss or downregulation of tuberin seems to be epigenetic, as alterations of TSC2 are not known in these tumors. The absence or reduction of tuberin might contribute to their proliferation.

LABORATORY/RADIOLOGIC/OTHER TESTS CHARACTERIZATION

Radiographs

CT radiologic study Characteristic subependymal calcifications

CLINICAL AND GROSS VARIANTS CHARACTERIZATION

TSC2/PKD1 CONTIGUOUS GENE SYNDROME

Renal Disease in Adults With TSC2/PKD1 Contiguous Gene Syndrome
Guido Martignoni, M.D. ; Franco Bonetti, M.D. ; Maurizio Pea, M.D. ; Regina Tardanico, M.D. ; Matteo Brunelli, M.D. ; John N. Eble, M.D.

From the Dipartimento di Patologia-Sezione Anatomia Patologica (G.M, F.B., M.P., M.B.), Universita' di Verona, Verona; Dipartimento di Anatomia Patologica (R.T.), Universita' di Brescia, Brescia, Italy; and Roudebush VA Medical Center (J.N.E.), Indiana University, Indianapolis, Indiana, U.S.A.
Am J Surg Pathol 2002;26:198-205 Abstract quote
The most common renal lesions of tuberous sclerosis complex, an autosomal-dominant syndrome resulting from losses of TSC1 (9q34) or TSC2 (16p13.3), are renal cysts and angiomyolipomas. Epithelial neoplasms are less common. The TSC2 gene lies adjacent to PKD1 , the major gene responsible for autosomal-dominant polycystic kidney disease. Recently, a deletion mutation disrupting both TSC2 and PKD1 has been described in young children with tuberous sclerosis complex with severe renal cystic disease. This disease has been termed the TSC2/PKD1 contiguous gene syndrome.

We describe the lesions in the resected kidneys of two adults with TSC2/PDK1 contiguous gene syndrome, at the time of the nephrectomies: a 31-year-old man and his 44-year-old mother. The four kidneys were enlarged reniform masses composed of cysts lined by flattened, cuboidal, or, infrequently, large deeply eosinophilic epithelial cells. The kidneys also contained numerous classic angiomyolipomas and rare intraglomerular microlesions. In the son the largest tumor was a monotypic epithelioid angiomyolipoma. In the wall of his left renal pelvis there was a plaque-shaped, HMB-45-positive localized lesion of lymphangioleiomyomatosis. This is the first description of the renal lesions in adults with genetically confirmed TSC2/PDK1 contiguous gene syndrome.

The pathologic findings highlight the importance of thorough sampling for histology in polycystic kidney diseases and indicate that the observation of an angiomyolipoma in biopsy material from patients with enlarged cystic kidneys should suggest the diagnosis of TSC2/PKD1 contiguous gene syndrome, even in cases without ultrasonographic and macroscopic evidence of angiomyolipoma.

HISTOLOGICAL TYPES CHARACTERIZATION

VARIANTS

ANGIOFIBROMAS

Loss of expression of tuberin and hamartin in tuberous sclerosis complex-associated but not in sporadic angiofibromas.
Fackler I, DeClue JE, Rust H, Vu PA, Kutzner H, Rutten A, Kaddu S, Sander CA, Volkenandt M, Johnson MW, Vinters HV, Wienecke R.

Department of Dermatology, Ludwig-Maximilians-University Munich, Munich, Germany, National Cancer Institute, Laboratory of Cellular Oncology, Bethesda, MD, USA, Dermatohistopathologische Gemeinschaftspraxis, Friedrichshafen, Germany, Department of Dermatology, University of Graz, Graz, Austria, Department of Pathology & Laboratory Medicine, University of California Los Angeles School of Medicine, Los Angeles, CA, USA.
J Cutan Pathol 2003 Mar;30(3):174-177 Abstract quote
BACKGROUND: Angiofibromas occur sporadically, and they develop in most patients with tuberous sclerosis complex (TSC), which is associated with alterations of the tumor suppressor genes TSC1 or TSC2. Loss of tuberin, the protein product of TSC2, has been shown in the interstitial fibroblast compartment of TSC-associated angiofibromas. It is unclear whether there is also a loss of hamartin, the product of TSC1 in TSC-associated and sporadic angiofibromas.

METHODS: The expression of hamartin and tuberin was analyzed by immunohistochemistry in 59 TSC-associated and 12 sporadic angiofibromas using affinity-purified antibodies.

RESULTS: Loss of expression of both tuberin and hamartin was detected in 14 angiofibromas, loss of only tuberin in three, and loss of only hamartin in four TSC-associated angiofibromas; but there was no loss in the sporadic angiofibromas. Only the interstitial cells, but not the vascular cells, showed a loss of expression of tuberin or hamartin.

CONCLUSIONS: Loss of tuberin or hamartin occurred in a minority of the TSC-linked angiofibromas, but not in the sporadic angiofibromas. The absence of both tuberin and hamartin in some of the tumors suggests that the stability of tuberin and hamartin, which are believed to form an active complex in vivo, is negatively affected by the absence of either of the partners.

CLEAR CELL RENAL CARCINOMA

Mutational analysis of the von hippel lindau gene in clear cell renal carcinomas from tuberous sclerosis complex patients.

Duffy K, Al-Saleem T, Karbowniczek M, Ewalt D, Prowse AH, Henske EP.

Medical Oncology Division (KD, MK, AHP, EPH) and Department of Pathology (TA-S), Fox Chase Cancer Center, Philadelphia, Pennsylvania.
Mod Pathol 2002 Mar;15(3):205-10 Abstract quote
Tuberous sclerosis complex (TSC) is an autosomal-dominant disorder characterized by seizures, mental retardation, autism, and tumors of multiple organs. Renal disease in TSC includes angiomyolipomas, cysts, and renal cell carcinomas. It is known that somatic mutations in the von Hippel Lindau (VHL) tumor suppressor gene occur in most clear cell renal carcinomas.

To determine whether TSC-associated clear cell carcinomas also contain VHL mutations, we analyzed six tumors for loss of heterozygosity in the VHL gene region of chromosome 3p and for mutations in the VHL gene. Four of the patients were women between the ages of 34 and 68 years, and two were males under the age of 21 years. The loss of heterozygosity analysis was performed using polymorphic microsatellite markers, and the mutational analysis was performed using direct sequencing. Chromosome 3p loss of heterozygosity was not detected, and no VHL mutations were identified.

These findings suggest that mutations in the TSC1 and TSC2 genes lead to clear cell renal carcinogenesis via an alternate pathway not involving VHL mutations.

MULTIFOCAL MICRONODULAR PNEUMOCYTE HYPERPLASIA

Multifocal Micronodular Pneumocyte Hyperplasia and Lymphangioleiomyomatosis in Tuberous Sclerosis with a TSC2 Gene

Hiroshi Maruyama, M.D., Kuniaki Seyama, M.D., Junko Sobajima, M.D., Kazumichi Kitamura, M.D., Tooru Sobajima, M.D., Tomokazu Fukuda, Ph.D., Kaoru Hamada, M.D., Masahiro Tsutsumi, M.D., Okio Hino, M.D. and Yoichi Konishi, M.D.

Departments of Pathology (HM), Internal Medicine (JS, KK), and Thoracic Surgery (TS), Hoshigaoka Koseinenkin Hospital, Hirakata, Japan; Department of Respiratory Medicine (KS), School of Medicine, Juntendo University, Tokyo, Japan; Department of Experimental Pathology (TF, OH), Cancer Institute, Tokyo, Japan; and Second Department of Internal Medicine (KH) and Department of Oncological Pathology (MT, KY), Cancer Center, Nara Medical University, Kashihara, Japan

Mod Pathol 2001;14:609-614 Abstract quote

A 45-year-old woman with a long-standing diagnosis of tuberous sclerosis (TSC) is presented. She has multifocal micronodular pneumocyte hyperplasia (MMPH) and lymphangioleiomyomatosis (LAM) of the lung, together with the detection of TSC2 gene mutation. During surgery for spontaneous pneumothorax, an open-lung biopsy was performed. Micronodules were well defined, measuring approximately 4 mm in diameter.

These MMPHs were histologically composed of papillary proliferation of Type II pneumocytes, with positive immunoreactivity of keratin and surfactant apoprotein. The cystlike spaces, with dilatation and destruction of air spaces, were diffusely formed, and the walls were composed of the spindle cells.

Such LAM showed positive immunoreactivity for HMB-45 (a monoclonal antibody specific for human melanoma) and tuberin (the gene product of TSC2). On germline mutation analysis using leukocytes of the present patient, a TSC2 gene mutation was confirmed as a deletion of G (or g) on Exon 9 by polymerase chain reaction�single-strand conformational polymorphism. However, no mutation was detected in her son. With microdissection analysis using paraffin-embedding lung tissues, LOH of the TSC2 gene preliminarily was detected in a LAM lesion but not in MMPH.

It is suggested that MMPH, in addition to LAM, could be another pulmonary lesion in TSC patients and that the detection of TSC2 and/or TSC1 gene could essentially be useful for the pathogenesis of MMPH and LAM in TSC patients.

PERIVASCULAR EPITHELIOID CELLS (PEC) Has been proposed that all tumors are derived from this cell which is of smooth muscle derivation and expresses HMB-45

Abdominopelvic Sarcoma of Perivascular Epithelioid Cells. Report of Four Cases in Young Women, One with Tuberous Sclerosis

Franco Bonetti, M.D., Guido Martignoni, M.D., Chiara Colato, M.D., Erminia Manfrin, M.D., Marcello Gambacorta, M.D., Maurizio Faleri, M.D., Carlos Bacchi, M.D., Vai-Chong Sin, MBBS, Nim-Lai Wong, M.D., Mark Coady, M.D. and John Kwok-cheung Chan, M.D.

Istituto di Anatomia Patologica (FB, GM, EM, CC), Universit� di Verona; Servizio di Anatomia Patologica (MG, MF), Ospedale Niguarda, Milano, Italy; Department of Pathology (CB), Facultade Medicina-UNESP Botucatu, Brasil; Department of Pathology and Clinical Oncology (VCS, JKCC), Queen Elizabeth Hospital, Hong Kong; Department of Anatomical Pathology (MC), SEALS Prince of Wales Hospital, Sidney, Australia; and Department of Pathology (NLW), Kinag Wu Hospital, Macau

Mod Pathol 2001;14:563-568 Abstract quote

The perivascular epithelioid cell has been proposed to be the unifying proliferating cell type in a number of lesions such as angiomyolipoma, lymphangiomyomatosis, clear cell "sugar" tumor and renal capsuloma. With the exception of rare examples of angiomyolipoma, they are non-metastasizing.

We report four examples of a new member of this family of perivascular epithelioid cell neoplasms that occur in abdominopelvic location and show metastatic properties.

The patients, all women, were aged 19 to 41 years (mean, 32), and presented with a tumor mass involving the serosa of the ileum, uterus or pelvic cavity. Morphologically, the tumors were composed of sheets of large polygonal cells with glycogen-rich clear or eosinophilic cytoplasm and moderately pleomorphic nuclei, traversed by a delicate vasculature, mimicking clear cell carcinoma. There were areas of coagulative necrosis and occasional mitotic figures. Intracytoplasmic brown pigment was present in two cases. Spindly cells, smooth muscle and fat were absent. Lymphovascular invasion was present in all, lymph node metastasis was documented in two and metastasis to the ovary was present in one case.

Two patients developed widespread metastatic disease after 10 and 28 months from diagnosis. One patient showed the clinical signs of tuberous sclerosis. In spite of the epithelial-like appearance, the tumor cells were negative for epithelial markers but were strongly positive with the melanogenesis-related marker HMB45. Another melanogenesis marker (MART-1) was positive in two cases. Other markers including S-100 protein, vimentin, muscle-specific actin, desmin and chromogranin A were negative.

Thus, these tumors are not readily classifiable in the existing schema of known entities, and show overlapping morpho-phenotypic features of clear cell "sugar" tumor of the lung and epithelioid angiomyolipoma. We consider them as sarcomas composed of a pure population of uncommitted perivascular epithelioid cell, that lack modulation toward smooth muscle or adipose cells.

SPECIAL STAINS/IMMUNOPEROXIDASE/OTHER CHARACTERIZATION

Immunoperoxidase

HMB45 and MART1
This stain is usually used to confirm melanomas-it is often positive in many of the proliferations associated with TSC including renal angiomyolipomas and lymphangioleiomyomatosis

Arch Neurol 2000;57:662-665.
Henry JB. Clinical Diagnosis and Management by Laboratory Methods. Twentieth Edition. WB Saunders. 2001.
Rosai J. Ackerman's Surgical Pathology. Eight Edition. Mosby 1996.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.
Robbins Pathologic Basis of Disease. Sixth Edition. WB Saunders 1999.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 5th Edition. McGraw-Hill. 1999.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.

Commonly Used Terms

Angiomyolipoma of the Kidney

Lymphangioleiomyomatosis

PEC Tumors

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Internet Links

Last Updated 4/17/2003

ADDITIONAL PATHOGENETIC MECHANISMS	CHARACTERIZATION
GENERAL
Tuberous sclerosis-associated lesions of the kidney, brain, and skin are angiogenic neoplasms Jack L. Arbiser, MD, PhD Daniel Brat, MD, PhD Steve Hunter, MD, etal. Atlanta, Georgia, New York, New York, Philadelphia, Pennsylvania, and Tucson, Arizona	J Am Acad Dermatol 2002;46:376-80 Abstract quote Background: Tuberous sclerosis is an autosomal dominant condition characterized by the development of benign neoplasms of the brain, kidney, and skin. Progressive growth and malignant transformation of brain and kidney lesions constitute the major cause of morbidity and mortality in adults with tuberous sclerosis. In addition, growth of skin lesions may be disfiguring to patients. Objective: The purpose of this study was to determine whether benign tumors in patients with tuberous sclerosis are angiogenic. Methods: Brain, kidney, and skin tumors from patients with tuberous sclerosis were stained with CD31, a specific marker of vascular endothelium. In addition, we used Northern blot analysis to demonstrate that renal angiomyolipoma cells express the potent angiogenesis stimulator vascular endothelial growth factor (VEGF). Results: Brain, kidney, and skin neoplasms from patients with tuberous sclerosis are highly angiogenic. Renal angiomyolipoma cells produce the potent angiogenic factor VEGF. Conclusion: Benign neoplasms of patients with tuberous sclerosis are highly vascular. Our results provide a rationale for antiangiogenic therapy in the treatment and prevention of tuberous sclerosis-associated neoplasms.
TUBERIN
Loss of tuberin, the tuberous-sclerosis-complex-2 gene product is associated with angiogenesis Phuong-Anh Nguyen-Vu1, Ingrid Fackler1, Adelheid Rust2, Jeffrey E. DeClue3, Christian A. Sander1, Matthias Volkenandt1, Michael Flaig1, Raymond S. Yeung4 and Ralf Wienecke1 1 Department of Dermatology, Ludwig-Maximilians-University Munich, Munich, Germany, 2 Department of Dermatology, Mayo Clinic and Foundation, Rochester, Minnesota, USA, 3 National Cancer Institute, Laboratory of Cellular Oncology, Bethesda, Maryland, USA, 4 Department of Surgery & Division of Medical Genetics, University of Washington, Seattle, Washington, USA	Journal of Cutaneous Pathology 2001;28 (9), 470-475 Background: Tuberous sclerosis complex (TSC) is an autosomal dominantly inherited disorder associated with an alteration of the TSC2 tumor suppressor gene which encodes for the protein product tuberin. The disease is characterized by the development of hamartomas, e.g. cutaneous angiofibromas which consist of vascular cells, interstitial cells, and normal components of the skin. The Eker rat model, an animal model of inherited cancer, has been shown to carry a mutation of TSC2. Methods: Immunohistochemical analyses of human angiofibromas were performed using antibodies directed against tuberin and angiogenic growth factors. Proliferation of human dermal microvascular endothelial cells (HDMEC) was determined after incubation with the supernatants of TSC2 (+/+) and TSC2 (-/-) rat embryonic fibroblasts (REF) that were derived from the Eker strain. Results: Loss of the expression of tuberin was observed in the interstitial cells of 13 of 39 angiofibromas. The expression of tuberin was retained in the vascular cells. In all analyzed angiofibromas, the angiogenic factors bFGF, PD-ECGF, VEGF and angiogenin were detected in the interstitial cells and/or vascular cells. Expression of PDGF-B and TGF-b1 was weak. Tissue culture supernatants from TSC2 (-/-) REF stimulated the growth of HDMEC significantly more than supernatants from TSC2 (+/+) REF. Conclusion: A functional loss of tuberin may stimulate vascular growth.
Reduction of expression of tuberin, the tuberous-sclerosis-complex-gene-2 product in tuberous sclerosis complex associated connective tissue nevi and sporadic squamous and basal cell carcinomas. Wienecke R, Klemm E, Karparti S, Swanson NA, Green AJ, DeClue JE. Department of Dermatology and Allergology, Ludwig-Maximilians-University Munich, Munich, Germany, National Institutes of Health, National Cancer Institute, Laboratory of Cellular Oncology, Bethesda, Maryland, USA, Department of Dermatology, Semmelweis University, Budapest, Hungary, Oregon Health Sciences University, Department of Dermatology, Portland, Oregon, USA, Department of Medical Genetics and Conway Institute, University College Dublin, Ireland	J Cutan Pathol 2002 May;29(5):287-290 Abstract quote Background: Patients affected with tuberous sclerosis complex (TSC) are prone to the development of multiple benign tumors of the skin and other organs. Tuberin, the protein product of the tuberous-sclerosis-complex-2 tumor suppressor gene (TSC2) has been shown to inhibit cell proliferation. In TSC associated kidney tumors and sporadic brain tumors the loss/reduction of tuberin has been shown. Methods: Specimens of nine squamous cell carcinomas (SCC) and five basal cell carcinomas (BCC) from patients without TSC and six biopsies of connective tissue nevi (CTN) of patients with TSC were obtained. Specimens were analyzed by immunoblotting for the expression of tuberin. Results: Absent or reduced levels of tuberin were detected in the dermal parts of three of six shagreen patches, two of five BCC, and four of nine SCC. Conclusions: In tumors/hamartomas of patients with TSC the complete loss of TSC2 and tuberin is a mechanism which could be shown for CTN, thereby excluding the possibility of haploinsufficiency of TSC2. In a substantial number of cutaneous BCC and SCC the loss or downregulation of tuberin seems to be epigenetic, as alterations of TSC2 are not known in these tumors. The absence or reduction of tuberin might contribute to their proliferation.

Major Features	Minor Features
Facial angiofibromas or forehead plaque Nontraumatic ungual or periungual fibroma Hypomelanotic macules (more than 3) Shagreen patch (connective tissue nevus) Multiple renal nodular hamartomas Cortical tuber* Subependymal nodule Subependymal giant cell astrocytoma Cardiac rhabdomyoma, single or multiple Lymphangiomyomatosis Renal angiomyolipoma	Multiple randomly distributed pits in dental enamel Hamartomatous rectal polyps Bone cysts Cerebral white matter migration lines-may be diagnosed radiologically Gingival fibromas Nonrenal hamartomas Retinal achromatic patch Confetti skin lesions Multiple renal cysts

Epidemiology
Disease Associations
Pathogenesis
Laboratory/Radiologic/Other Diagnostic Testing
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/Immunohistochemistry/Electron Microscopy
Differential Diagnosis
Prognosis
Treatment
Commonly Used Terms
Internet Links

EPIDEMIOLOGY	CHARACTERIZATION
SYNONYMS	Bourneville disease
INCIDENCE	1/8000

CHARACTERIZATION	TSC1	TSC2
Chromosome location	9q34	16p13
Mutational spectrum, %
Large deletion and rearrangement	2	17
Small deletion and insertion	56	33
Nonsense	37	20
Splice	5	6
Misense	0	23
Number of exons	139	250
mRNA size in KB	8.6	5.5
Protein product length	1164	1784
Protein product name	Hamartin	Tuberin
Protein function	Associates physically with tuberin	Negative growth regulator Putatative GTPase activating protein for rap1 and rab5

LABORATORY/RADIOLOGIC/OTHER TESTS	CHARACTERIZATION
Radiographs
CT radiologic study	Characteristic subependymal calcifications

HISTOLOGICAL TYPES	CHARACTERIZATION
VARIANTS
ANGIOFIBROMAS
Loss of expression of tuberin and hamartin in tuberous sclerosis complex-associated but not in sporadic angiofibromas. Fackler I, DeClue JE, Rust H, Vu PA, Kutzner H, Rutten A, Kaddu S, Sander CA, Volkenandt M, Johnson MW, Vinters HV, Wienecke R. Department of Dermatology, Ludwig-Maximilians-University Munich, Munich, Germany, National Cancer Institute, Laboratory of Cellular Oncology, Bethesda, MD, USA, Dermatohistopathologische Gemeinschaftspraxis, Friedrichshafen, Germany, Department of Dermatology, University of Graz, Graz, Austria, Department of Pathology & Laboratory Medicine, University of California Los Angeles School of Medicine, Los Angeles, CA, USA.	J Cutan Pathol 2003 Mar;30(3):174-177 Abstract quote BACKGROUND: Angiofibromas occur sporadically, and they develop in most patients with tuberous sclerosis complex (TSC), which is associated with alterations of the tumor suppressor genes TSC1 or TSC2. Loss of tuberin, the protein product of TSC2, has been shown in the interstitial fibroblast compartment of TSC-associated angiofibromas. It is unclear whether there is also a loss of hamartin, the product of TSC1 in TSC-associated and sporadic angiofibromas. METHODS: The expression of hamartin and tuberin was analyzed by immunohistochemistry in 59 TSC-associated and 12 sporadic angiofibromas using affinity-purified antibodies. RESULTS: Loss of expression of both tuberin and hamartin was detected in 14 angiofibromas, loss of only tuberin in three, and loss of only hamartin in four TSC-associated angiofibromas; but there was no loss in the sporadic angiofibromas. Only the interstitial cells, but not the vascular cells, showed a loss of expression of tuberin or hamartin. CONCLUSIONS: Loss of tuberin or hamartin occurred in a minority of the TSC-linked angiofibromas, but not in the sporadic angiofibromas. The absence of both tuberin and hamartin in some of the tumors suggests that the stability of tuberin and hamartin, which are believed to form an active complex in vivo, is negatively affected by the absence of either of the partners.
CLEAR CELL RENAL CARCINOMA
Mutational analysis of the von hippel lindau gene in clear cell renal carcinomas from tuberous sclerosis complex patients. Duffy K, Al-Saleem T, Karbowniczek M, Ewalt D, Prowse AH, Henske EP. Medical Oncology Division (KD, MK, AHP, EPH) and Department of Pathology (TA-S), Fox Chase Cancer Center, Philadelphia, Pennsylvania.	Mod Pathol 2002 Mar;15(3):205-10 Abstract quote Tuberous sclerosis complex (TSC) is an autosomal-dominant disorder characterized by seizures, mental retardation, autism, and tumors of multiple organs. Renal disease in TSC includes angiomyolipomas, cysts, and renal cell carcinomas. It is known that somatic mutations in the von Hippel Lindau (VHL) tumor suppressor gene occur in most clear cell renal carcinomas. To determine whether TSC-associated clear cell carcinomas also contain VHL mutations, we analyzed six tumors for loss of heterozygosity in the VHL gene region of chromosome 3p and for mutations in the VHL gene. Four of the patients were women between the ages of 34 and 68 years, and two were males under the age of 21 years. The loss of heterozygosity analysis was performed using polymorphic microsatellite markers, and the mutational analysis was performed using direct sequencing. Chromosome 3p loss of heterozygosity was not detected, and no VHL mutations were identified. These findings suggest that mutations in the TSC1 and TSC2 genes lead to clear cell renal carcinogenesis via an alternate pathway not involving VHL mutations.
MULTIFOCAL MICRONODULAR PNEUMOCYTE HYPERPLASIA
Multifocal Micronodular Pneumocyte Hyperplasia and Lymphangioleiomyomatosis in Tuberous Sclerosis with a TSC2 Gene Hiroshi Maruyama, M.D., Kuniaki Seyama, M.D., Junko Sobajima, M.D., Kazumichi Kitamura, M.D., Tooru Sobajima, M.D., Tomokazu Fukuda, Ph.D., Kaoru Hamada, M.D., Masahiro Tsutsumi, M.D., Okio Hino, M.D. and Yoichi Konishi, M.D. Departments of Pathology (HM), Internal Medicine (JS, KK), and Thoracic Surgery (TS), Hoshigaoka Koseinenkin Hospital, Hirakata, Japan; Department of Respiratory Medicine (KS), School of Medicine, Juntendo University, Tokyo, Japan; Department of Experimental Pathology (TF, OH), Cancer Institute, Tokyo, Japan; and Second Department of Internal Medicine (KH) and Department of Oncological Pathology (MT, KY), Cancer Center, Nara Medical University, Kashihara, Japan	Mod Pathol 2001;14:609-614 Abstract quote A 45-year-old woman with a long-standing diagnosis of tuberous sclerosis (TSC) is presented. She has multifocal micronodular pneumocyte hyperplasia (MMPH) and lymphangioleiomyomatosis (LAM) of the lung, together with the detection of TSC2 gene mutation. During surgery for spontaneous pneumothorax, an open-lung biopsy was performed. Micronodules were well defined, measuring approximately 4 mm in diameter. These MMPHs were histologically composed of papillary proliferation of Type II pneumocytes, with positive immunoreactivity of keratin and surfactant apoprotein. The cystlike spaces, with dilatation and destruction of air spaces, were diffusely formed, and the walls were composed of the spindle cells. Such LAM showed positive immunoreactivity for HMB-45 (a monoclonal antibody specific for human melanoma) and tuberin (the gene product of TSC2). On germline mutation analysis using leukocytes of the present patient, a TSC2 gene mutation was confirmed as a deletion of G (or g) on Exon 9 by polymerase chain reaction�single-strand conformational polymorphism. However, no mutation was detected in her son. With microdissection analysis using paraffin-embedding lung tissues, LOH of the TSC2 gene preliminarily was detected in a LAM lesion but not in MMPH. It is suggested that MMPH, in addition to LAM, could be another pulmonary lesion in TSC patients and that the detection of TSC2 and/or TSC1 gene could essentially be useful for the pathogenesis of MMPH and LAM in TSC patients.
PERIVASCULAR EPITHELIOID CELLS (PEC)	Has been proposed that all tumors are derived from this cell which is of smooth muscle derivation and expresses HMB-45
Abdominopelvic Sarcoma of Perivascular Epithelioid Cells. Report of Four Cases in Young Women, One with Tuberous Sclerosis Franco Bonetti, M.D., Guido Martignoni, M.D., Chiara Colato, M.D., Erminia Manfrin, M.D., Marcello Gambacorta, M.D., Maurizio Faleri, M.D., Carlos Bacchi, M.D., Vai-Chong Sin, MBBS, Nim-Lai Wong, M.D., Mark Coady, M.D. and John Kwok-cheung Chan, M.D. Istituto di Anatomia Patologica (FB, GM, EM, CC), Universit� di Verona; Servizio di Anatomia Patologica (MG, MF), Ospedale Niguarda, Milano, Italy; Department of Pathology (CB), Facultade Medicina-UNESP Botucatu, Brasil; Department of Pathology and Clinical Oncology (VCS, JKCC), Queen Elizabeth Hospital, Hong Kong; Department of Anatomical Pathology (MC), SEALS Prince of Wales Hospital, Sidney, Australia; and Department of Pathology (NLW), Kinag Wu Hospital, Macau	Mod Pathol 2001;14:563-568 Abstract quote The perivascular epithelioid cell has been proposed to be the unifying proliferating cell type in a number of lesions such as angiomyolipoma, lymphangiomyomatosis, clear cell "sugar" tumor and renal capsuloma. With the exception of rare examples of angiomyolipoma, they are non-metastasizing. We report four examples of a new member of this family of perivascular epithelioid cell neoplasms that occur in abdominopelvic location and show metastatic properties. The patients, all women, were aged 19 to 41 years (mean, 32), and presented with a tumor mass involving the serosa of the ileum, uterus or pelvic cavity. Morphologically, the tumors were composed of sheets of large polygonal cells with glycogen-rich clear or eosinophilic cytoplasm and moderately pleomorphic nuclei, traversed by a delicate vasculature, mimicking clear cell carcinoma. There were areas of coagulative necrosis and occasional mitotic figures. Intracytoplasmic brown pigment was present in two cases. Spindly cells, smooth muscle and fat were absent. Lymphovascular invasion was present in all, lymph node metastasis was documented in two and metastasis to the ovary was present in one case. Two patients developed widespread metastatic disease after 10 and 28 months from diagnosis. One patient showed the clinical signs of tuberous sclerosis. In spite of the epithelial-like appearance, the tumor cells were negative for epithelial markers but were strongly positive with the melanogenesis-related marker HMB45. Another melanogenesis marker (MART-1) was positive in two cases. Other markers including S-100 protein, vimentin, muscle-specific actin, desmin and chromogranin A were negative. Thus, these tumors are not readily classifiable in the existing schema of known entities, and show overlapping morpho-phenotypic features of clear cell "sugar" tumor of the lung and epithelioid angiomyolipoma. We consider them as sarcomas composed of a pure population of uncommitted perivascular epithelioid cell, that lack modulation toward smooth muscle or adipose cells.

SPECIAL STAINS/IMMUNOPEROXIDASE/OTHER	CHARACTERIZATION
Immunoperoxidase
HMB45 and MART1	This stain is usually used to confirm melanomas-it is often positive in many of the proliferations associated with TSC including renal angiomyolipomas and lymphangioleiomyomatosis