Extrarenal Angiomyolipoma

Background

This rare tumor has primarily been described in the kidney. However, surgical pathologists have identified this tumor in numerous other organs. It may be associated with Tuberous Sclerosis.

OUTLINE

Disease Associations

Gross Appearance and Clinical Variants

Histopathological Features and Variants

Special Stains/Immunohistochemistry/Electron Microscopy

Differential Diagnosis

Prognosis and Treatment

Commonly Used Terms

DISEASE ASSOCIATIONS CHARACTERIZATION

TUBEROUS SCLEROSIS

GROSS APPEARANCE/
CLINICAL VARIANTS CHARACTERIZATION

GENERAL

VARIANTS

BONE

Primary monotypic epithelioid angiomyolipoma of bone.

Insabato L, De Rosa G, Terracciano LM, Fazioli F, Di Santo F, Rosai J.

Dipartimento di Anatomia Patologica, Facolta di Medicina, Universita Federico II, Napoli, Italy.
Histopathology 2002 Mar;40(3):286-90 Abstract quote
AIMS: Monotypic epithelioid angiomyolipoma is a distinct and definable variant of angiomyolipoma, composed of monomorphous epithelioid cells that show HMB45 immunoreactivity. Angiomyolipoma, including its morphological variants, belongs to the family of perivascular epithelioid cell tumour.

METHODS AND RESULTS: The tumour was examined using immunohistochemical staining and by transmission electron microscopy. Neoplastic cells showed a cytoplasmic granular positivity for HMB45.

CONCLUSIONS: Extrarenal angiomyolipomas are rare and, to the best of our knowledge, this is the first reported case of a primary monotypic epithelioid angiomyolipoma of bone in a patient without evidence of tuberous sclerosis.

COLON

Angiomyolipoma of the colon: a new entity in colonic polypoid lesions.

Hikasa Y, Narabayashi T, Yamamura M, Fukuda Y, Tanida N, Tamura K, Ohno T, Shimoyama T, Nishigami T.

Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan.
Gastroenterol Jpn 1989 Aug;24(4):407-9 Abstract quote
A 67-year-old man with angiomyolipoma on the sigmoid colon is reported. The colonic polyp was pedunculated and diagnosed histologically after endoscopic polypectomy. Angiomyolipoma is one of the benign hamartomas arising principally in the kidneys of patients with or without tuberous sclerosis.

Extrarenal angiomyolipoma is rare and this may be the first report of colonic angiomyolipoma.

Angiomyolipoma arising in the colon.

Maesawa C, Tamura G, Sawada H, Kamioki S, Nakajima Y, Satodate R.

Department of Pathology, Iwate Medical University School of Medicine, Japan.
Am J Gastroenterol 1996 Sep;91(9):1852-4 Abstract quote
Extrarenal angiomyolipomas are very rare. Here we report the first case of surgically resected angiomyolipoma of the descending colon that developed in a 50-yr-old man. The patient had no signs of or family history of tuberous sclerosis. He underwent a partial colectomy because the tumor obstructed the colon.

Histologically, the tumor consisted of three components: mature fat cells, blood vessels, and smooth muscle cells, and was thereby diagnosed as an angiomyolipoma. Immunohistochemically, the proliferating smooth muscle cells were positive for vimentin, alpha-smooth muscle actin, and desmin. The tumor cells were negative for HMB-45, which is consistently expressed in renal angiomyolipomas.

HEART

Intramyocardial angiomyolipoma.

Shimizu M, Manabe T, Tazelaar HD, Hirokawa M, Moriya T, Ito J, Hamanaka S, Hata T.

Department of Pathology, Kawasaki Medical School, Okayama, Japan.
Am J Surg Pathol 1994 Nov;18(11):1164-9 Abstract quote
We report a case of cardiac angiomyolipoma in a 48-year-old woman who went to the hospital because of shortness of breath. Cardiac ultrasonography showed a right atrial mass, which was surgically removed. Pathologic examination revealed a 6-cm-diameter, dome-shaped mass composed of a mixture of blood vessels, smooth muscle, and fat. Because of its distinctive morphology and location, we diagnosed it as an intramyocardial angiomyolipoma. There was no evidence of tuberous sclerosis. Since excision of the mass, the patient has remained well without recurrence for 20 months. Angiomyolipomas usually develop in the kidney; extrarenal occurrence is rare.

To date, no case of a cardiac angiomyolipoma has been reported in the English literature. The histogenesis of angiomyolipoma is uncertain, but it is most likely hamartomatous in nature.

LUNG

Angiomyolipoma of the lung.

Ito M, Sugamura Y, Ikari H, Sekine I.

Department of Molecular Pathology, Nagasaki University School of Medicine, Japan.
Arch Pathol Lab Med 1998 Nov;122(11):1023-5 Abstract quote
Extrarenal angiomyolipomas are rare tumors that have been reported in several organs, including the liver, reproductive organs, skin, and retroperitoneum.

In this report, we present the clinicopathologic findings of an angiomyolipoma of the lung in a 67-year-old man with no history of tuberous sclerosis or lymphangioleiomyomatosis. To our knowledge, this is the second reported case of pulmonary angiomyolipoma. The tumor was coincidentally found in the left lower lung in association with a hemothorax.

Our case was histologically identical to angiomyolipoma occurring in the kidney, but immunohistologic staining for HMB-45 was negative, similar to the first reported case.

OVARY

Epithelioid angiomyolipoma of the ovary: a case report and literature review.

Anderson AE, Yang X, Young RH.

Department of Pathology, Long Island Jewish Medical Center, New Hyde Park, New York 11040, USA.
Int J Gynecol Pathol 2002 Jan;21(1):69-73 Abstract quote
Angiomyolipoma (AML) is a benign mesenchymal neoplasm that mainly occurs in the kidney either sporadically or in patients with tuberous sclerosis complex (TSC). Extrarenal AML is uncommon.

We describe a 39-year-old female with a history of TSC and bilateral multicentric renal AML who presented with a persistent cystic ovarian mass that fluctuated in size during 2 years of ultrasonographic observation before its removal by salpingo-oophorectomy. The 4.5-cm mass was solid and cystic and tan-yellow. Microscopic examination showed an admixture of epithelioid cells, smooth muscle bundles, large thick-walled blood vessels, and mature adipose tissue. The epithelioid cells had abundant eosinophilic cytoplasm and many had bizarre atypical nuclei including multinucleated forms. Mitoses were rare. Typical smooth muscle cells and the epithelioid cells were strongly immunoreactive for HMB-45.

To our knowledge, this represents the first report of an AML arising in the ovary. The differential with other oxyphilic tumors of the ovary is discussed.

PAROTID GLAND

Angiomyolipoma of the parotid gland: a case report.

Foschini MP, Corti B, DaCol M, Cenzi M, Zanella F, Barbazza R.

Department of Oncology, Ospedale Bellaria, University of Bologna, Italy.

Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999 Jun;87(6):738-41 Abstract quote
Angiomyolipoma is a hamartomatous process that most frequently occurs as a single lesion or multiple foci in the kidneys of patients affected by tuberous sclerosis. Angiomyolipoma can also arise in extrarenal sites, among which the liver is the most frequently recorded. Only rare cases of angiomyolipoma located in the head and neck region (ear and oral and nasal cavity) have been described.

The purpose of the present article is to report a case of angiomyolipoma of the parotid gland. A 68-year-old woman appeared for treatment with a slow-growing nodule located in her right parotid gland. Ultrasound examination revealed a heterogeneous nodule with well-defined margins. The nodule was surgically removed by total parotidectomy and showed the characteristic appearance of angiomyolipoma, with an admixture of fat smooth muscle cells, and tortuous, thick-walled blood vessels. Careful physical examination of the patient failed to reveal features of tuberous sclerosis.

Angiomyolipoma should be considered in the differential diagnosis of mesenchymal lesions involving the salivary gland.

RETROPERITONEUM

Retroperitoneal extrarenal angiomyolipoma with early gastric carcinoma.

Mogi Y, Takimoto R, Kura T, Tamakawa M, Sakamaki S, Niitsu Y.

Department of Internal Medicine, Naganuma Municipal Hospital, Hokkaido, Japan.

J Gastroenterol 1998 Feb;33(1):86-90 Abstract quote
We present a very rare case of a retroperitoneal extrarenal angiomyolipoma accompanied by early gastric cancer. A 41-year-old Japanese man, who had undergone surgery for a type IIc early gastric cancer 2 years earlier, was admitted to hospital presenting with back pain and abdominal fullness.

Computed tomographic scanning and magnetic resonance imaging of the abdomen disclosed a massive fatty tumor extending from the hepatic hilus to the retroperitoneum. A large retroperitoneal tumor mass with no sign of involvement in the kidney was totally resected by radical surgery. Histologically, the tumor was classified as an angiomyolipoma.

SKIN

Cutaneous angiomyolipoma. A light-microscopic, immunohistochemical, and electron-microscopic study.

Argenyi ZB, Piette WW, Goeken JA.

Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City 52242.
Am J Dermatopathol 1991 Oct;13(5):497-502 Abstract quote
We report a case of cutaneous angiomyolipoma found on the helix of a 67-year-old man. The lesion was studied by routine light microscopy, special stains, immunohistochemical methods, and electron microscopy.

Histologic examination showed a well-circumscribed nodule in the dermis composed of an intimate mixture of blood vessels, smooth muscle, and mature fat. These components were confirmed by special stains, immunohistochemistry, and electron microscopy. We concluded that the unique features of this lesion distinguish it from other lesions such as angiomyoma, angiolipoma, and other mixed mesenchymal tumors.

This report demonstrates that the features considered diagnostic of angiomyolipoma can occur in extrarenal sites and, therefore, this diagnosis cannot be excluded on the basis of site alone.

SPERMATIC CORD

Angiomyolipoma of the spermatic cord: case report and literature review.

Castillenti TA, Bertin AP.

Department of Surgery, Doctors Hospital of Stark County Inc., Massillon, Ohio.
J Urol 1989 Nov;142(5):1308-9 Abstract quote
A case of an extrarenal angiomyolipoma in the spermatic cord is presented. Angiomyolipomas are uncommon tumors usually found in the kidney. The common embryological origin of kidney and cord structures offers a theoretical basis for the occurrence of such a neoplasm at this remote site.

Complete wide excision is curative and recurrences are infrequent.

SUBGALEAL

Subgaleal angiomyolipoma.

Tamura A, Ishikawa O, Miyachi Y.

Department of Dermatology, Gunma University School of Medicine, Japan.
J Dermatol 1994 Jul;21(7):514-7 Abstract quote
A case of angiomyolipoma found in the subgaleal lesion is reported. Lipoma appearing between the galea and periosteum of the frontal bone is called subgaleal or subfascial lipoma and usually consists histopathologically of mature fat cells.

We experienced a case of so-called subgaleal lipoma; however, the distinctive histologic features of our case were the proliferation of non-striated muscle fibers and small vessels scattered throughout the mature fat cells, which were compatible with angiomyolipoma. Extrarenal angiomyolipoma, especially cutaneous angiomyolipoma, are very rarely mentioned in the literature.

Our case is the second reported patient with angiomyolipoma in the subgaleal location.

UTERUS

Uterine angiomyolipoma: case report and review of the literature.

Yaegashi H, Moriya T, Soeda S, Yonemoto Y, Nagura H, Sasano H.

Department of Pathology, Mitokyodo General Hospital, Mito, Japan.
Pathol Int 2001 Nov;51(11):896-901 Abstract quote
Extrarenal angiomyolipomas (AML) have been reported at various anatomical sites, but infrequently in the gynecological region. In the uterus, only a few cases have been described.

We describe a uterine angiomyolipoma occurring in a 40-year-old woman without evidence of tuberous sclerosis. The tumor arose on the right wall of the uterine body and was partially cystic, and it was associated with marked degeneration. It was composed of mature adipose tissue, anomalous blood vessels and non-vascular smooth muscle cells. Immunohistochemistry revealed that non- vascular smooth muscle cells were positive for alpha-smooth muscle actin (alpha-SMA), desmin, vimentin, antihuman muscle actin (HHF35) and progesterone receptor (PR), and negative for cytokeratin, antihuman melanoma (HMB45), CD34, S-100 and estrogen receptor (ER).

It is of particular interest that non-vascular smooth muscle cells were negative for HMB45, in contrast to renal and other extrarenal AML in which HMB45 immunoreactivity has been demonstrated in these cells.

VAGINA

Angiomyolipoma of the vagina.

Chen KT.

Department of Pathology, Saint Agnes Medical Center, Fresno, California 93710.
Gynecol Oncol 1990 May;37(2):302-4 Abstract quote
An angiomyolipoma arising in the vaginal apex and presenting as a pelvic mass is reported and compared with other reported cases of extrarenal angiomyolipoma.

This case appears to be the second case of angiomyolipoma arising in the vaginal wall.

HISTOLOGICAL TYPES CHARACTERIZATION

GENERAL Similar to renal angiomyolipomas

VARIANTS

HIBERNOMA FEATURES

Extrarenal angiomyolipoma with melanocytic and hibernoma-like features.

Liwnicz BH, Weeks DA, Zuppan CW.

Department of Pathology, Loma Linda University, California 92354.

Ultrastruct Pathol 1994 Jul-Aug;18(4):443-8 Abstract quote
Angiomyolipoma is a tumor commonly occurring in the kidney, but occasionally found in extrarenal sites. Retroperitoneal angiomyolipoma with unusual features presenting in a 39 year old woman with hypertension is reported in this paper. Tumor fat was inconspicuous, and present largely as hibernoma-like microvesicular lipid. Tumor cells also demonstrated positivity for HMB-45 and S-100 protein, and by electron microscopy showed occasional cytoplasmic striated granules indistinguishable from stage II premelanosomes. However, electron microscopy and immunocytochemistry also confirmed the presence of a substantial myogenous component in the tumor, establishing the diagnosis of angiomyolipoma.

The implications of these findings, and the role of immunocytochemistry and electron microscopy in the diagnosis of this tumor are discussed.

SPECIAL STAINS/IMMUNOPEROXIDASE/
OTHER CHARACTERIZATION

SPECIAL STAINS

IMMUNOPEROXIDASE HMB45 positive

CD117

Expression of KIT (CD117) in Angiomyolipoma.

Makhlouf HR, Remotti HE, Ishak KG.

Department of Hepatic and Gastrointestinal Pathology, Armed Forces Institute of Pathology, Washington, DC, U.S.A.
Am J Surg Pathol 2002 Apr;26(4):493-7 Abstract quote
Angiomyolipoma is a unique mesenchymal tumor postulated to arise from perivascular epithelioid cells. Immunohistochemical studies have shown that angiomyolipomas express the melanocytic markers HMB-45, MART-1 (Melan A), microphthalmia transcription factor, and tyrosinase, in addition to smooth muscle actin. KIT (CD117) is a transmembrane growth factor receptor expressed in cells of melanocytic and a variety of other cell lineages. To date, KIT immunoreactivity has not been systematically studied in angiomyolipoma.

In this study we immunohistochemically analyzed a series of 21 angiomyolipomas (15 hepatic, six renal) with KIT. All were KIT positive: 14 of 21 (67%) with 3+ staining (>50% of tumor cells), 4 of 21 (19%) with 2+ staining (25-50% of tumor cells), and 3 of 21 (14%) with 1+ staining (<25% of tumor cells). In comparison, the percent of angiomyolipomas showing 3+ staining with HMB-45 was 62% and with Melan A was 52%. Positive KIT staining was detected in the epithelioid, spindle, and intermediate small round cells. Most cases showed diffuse cytoplasmic positivity. Strong perinuclear staining was present in the vacuolated clear epithelioid cells. There was focal KIT staining of fat cells. KIT was not detected in the endothelial cells lining blood vessels within the tumor. KIT may be a useful ancillary marker for the diagnosis of angiomyolipoma. A

ngiomyolipoma should be included in the differential diagnosis of KIT-positive tumors.

PROGNOSIS AND TREATMENT CHARACTERIZATION

PROGNOSTIC FACTORS

TREATMENT Excision

Rosai J. Ackerman's Surgical Pathology. Eight Edition. Mosby 1996.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.

Commonly Used Terms

Angiomyolipoma of the Kidney

Soft Tissue

Last Updated 4/8/2002

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Copyright � 2002 The Doctor's Doctor

GROSS APPEARANCE/ CLINICAL VARIANTS	CHARACTERIZATION
GENERAL
VARIANTS
BONE
Primary monotypic epithelioid angiomyolipoma of bone. Insabato L, De Rosa G, Terracciano LM, Fazioli F, Di Santo F, Rosai J. Dipartimento di Anatomia Patologica, Facolta di Medicina, Universita Federico II, Napoli, Italy.	Histopathology 2002 Mar;40(3):286-90 Abstract quote AIMS: Monotypic epithelioid angiomyolipoma is a distinct and definable variant of angiomyolipoma, composed of monomorphous epithelioid cells that show HMB45 immunoreactivity. Angiomyolipoma, including its morphological variants, belongs to the family of perivascular epithelioid cell tumour. METHODS AND RESULTS: The tumour was examined using immunohistochemical staining and by transmission electron microscopy. Neoplastic cells showed a cytoplasmic granular positivity for HMB45. CONCLUSIONS: Extrarenal angiomyolipomas are rare and, to the best of our knowledge, this is the first reported case of a primary monotypic epithelioid angiomyolipoma of bone in a patient without evidence of tuberous sclerosis.
COLON
Angiomyolipoma of the colon: a new entity in colonic polypoid lesions. Hikasa Y, Narabayashi T, Yamamura M, Fukuda Y, Tanida N, Tamura K, Ohno T, Shimoyama T, Nishigami T. Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan.	Gastroenterol Jpn 1989 Aug;24(4):407-9 Abstract quote A 67-year-old man with angiomyolipoma on the sigmoid colon is reported. The colonic polyp was pedunculated and diagnosed histologically after endoscopic polypectomy. Angiomyolipoma is one of the benign hamartomas arising principally in the kidneys of patients with or without tuberous sclerosis. Extrarenal angiomyolipoma is rare and this may be the first report of colonic angiomyolipoma.
Angiomyolipoma arising in the colon. Maesawa C, Tamura G, Sawada H, Kamioki S, Nakajima Y, Satodate R. Department of Pathology, Iwate Medical University School of Medicine, Japan.	Am J Gastroenterol 1996 Sep;91(9):1852-4 Abstract quote Extrarenal angiomyolipomas are very rare. Here we report the first case of surgically resected angiomyolipoma of the descending colon that developed in a 50-yr-old man. The patient had no signs of or family history of tuberous sclerosis. He underwent a partial colectomy because the tumor obstructed the colon. Histologically, the tumor consisted of three components: mature fat cells, blood vessels, and smooth muscle cells, and was thereby diagnosed as an angiomyolipoma. Immunohistochemically, the proliferating smooth muscle cells were positive for vimentin, alpha-smooth muscle actin, and desmin. The tumor cells were negative for HMB-45, which is consistently expressed in renal angiomyolipomas.
HEART
Intramyocardial angiomyolipoma. Shimizu M, Manabe T, Tazelaar HD, Hirokawa M, Moriya T, Ito J, Hamanaka S, Hata T. Department of Pathology, Kawasaki Medical School, Okayama, Japan.	Am J Surg Pathol 1994 Nov;18(11):1164-9 Abstract quote We report a case of cardiac angiomyolipoma in a 48-year-old woman who went to the hospital because of shortness of breath. Cardiac ultrasonography showed a right atrial mass, which was surgically removed. Pathologic examination revealed a 6-cm-diameter, dome-shaped mass composed of a mixture of blood vessels, smooth muscle, and fat. Because of its distinctive morphology and location, we diagnosed it as an intramyocardial angiomyolipoma. There was no evidence of tuberous sclerosis. Since excision of the mass, the patient has remained well without recurrence for 20 months. Angiomyolipomas usually develop in the kidney; extrarenal occurrence is rare. To date, no case of a cardiac angiomyolipoma has been reported in the English literature. The histogenesis of angiomyolipoma is uncertain, but it is most likely hamartomatous in nature.
LUNG
Angiomyolipoma of the lung. Ito M, Sugamura Y, Ikari H, Sekine I. Department of Molecular Pathology, Nagasaki University School of Medicine, Japan.	Arch Pathol Lab Med 1998 Nov;122(11):1023-5 Abstract quote Extrarenal angiomyolipomas are rare tumors that have been reported in several organs, including the liver, reproductive organs, skin, and retroperitoneum. In this report, we present the clinicopathologic findings of an angiomyolipoma of the lung in a 67-year-old man with no history of tuberous sclerosis or lymphangioleiomyomatosis. To our knowledge, this is the second reported case of pulmonary angiomyolipoma. The tumor was coincidentally found in the left lower lung in association with a hemothorax. Our case was histologically identical to angiomyolipoma occurring in the kidney, but immunohistologic staining for HMB-45 was negative, similar to the first reported case.
OVARY
Epithelioid angiomyolipoma of the ovary: a case report and literature review. Anderson AE, Yang X, Young RH. Department of Pathology, Long Island Jewish Medical Center, New Hyde Park, New York 11040, USA.	Int J Gynecol Pathol 2002 Jan;21(1):69-73 Abstract quote Angiomyolipoma (AML) is a benign mesenchymal neoplasm that mainly occurs in the kidney either sporadically or in patients with tuberous sclerosis complex (TSC). Extrarenal AML is uncommon. We describe a 39-year-old female with a history of TSC and bilateral multicentric renal AML who presented with a persistent cystic ovarian mass that fluctuated in size during 2 years of ultrasonographic observation before its removal by salpingo-oophorectomy. The 4.5-cm mass was solid and cystic and tan-yellow. Microscopic examination showed an admixture of epithelioid cells, smooth muscle bundles, large thick-walled blood vessels, and mature adipose tissue. The epithelioid cells had abundant eosinophilic cytoplasm and many had bizarre atypical nuclei including multinucleated forms. Mitoses were rare. Typical smooth muscle cells and the epithelioid cells were strongly immunoreactive for HMB-45. To our knowledge, this represents the first report of an AML arising in the ovary. The differential with other oxyphilic tumors of the ovary is discussed.
PAROTID GLAND
Angiomyolipoma of the parotid gland: a case report. Foschini MP, Corti B, DaCol M, Cenzi M, Zanella F, Barbazza R. Department of Oncology, Ospedale Bellaria, University of Bologna, Italy.	Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999 Jun;87(6):738-41 Abstract quote Angiomyolipoma is a hamartomatous process that most frequently occurs as a single lesion or multiple foci in the kidneys of patients affected by tuberous sclerosis. Angiomyolipoma can also arise in extrarenal sites, among which the liver is the most frequently recorded. Only rare cases of angiomyolipoma located in the head and neck region (ear and oral and nasal cavity) have been described. The purpose of the present article is to report a case of angiomyolipoma of the parotid gland. A 68-year-old woman appeared for treatment with a slow-growing nodule located in her right parotid gland. Ultrasound examination revealed a heterogeneous nodule with well-defined margins. The nodule was surgically removed by total parotidectomy and showed the characteristic appearance of angiomyolipoma, with an admixture of fat smooth muscle cells, and tortuous, thick-walled blood vessels. Careful physical examination of the patient failed to reveal features of tuberous sclerosis. Angiomyolipoma should be considered in the differential diagnosis of mesenchymal lesions involving the salivary gland.
RETROPERITONEUM
Retroperitoneal extrarenal angiomyolipoma with early gastric carcinoma. Mogi Y, Takimoto R, Kura T, Tamakawa M, Sakamaki S, Niitsu Y. Department of Internal Medicine, Naganuma Municipal Hospital, Hokkaido, Japan.	J Gastroenterol 1998 Feb;33(1):86-90 Abstract quote We present a very rare case of a retroperitoneal extrarenal angiomyolipoma accompanied by early gastric cancer. A 41-year-old Japanese man, who had undergone surgery for a type IIc early gastric cancer 2 years earlier, was admitted to hospital presenting with back pain and abdominal fullness. Computed tomographic scanning and magnetic resonance imaging of the abdomen disclosed a massive fatty tumor extending from the hepatic hilus to the retroperitoneum. A large retroperitoneal tumor mass with no sign of involvement in the kidney was totally resected by radical surgery. Histologically, the tumor was classified as an angiomyolipoma.
SKIN
Cutaneous angiomyolipoma. A light-microscopic, immunohistochemical, and electron-microscopic study. Argenyi ZB, Piette WW, Goeken JA. Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City 52242.	Am J Dermatopathol 1991 Oct;13(5):497-502 Abstract quote We report a case of cutaneous angiomyolipoma found on the helix of a 67-year-old man. The lesion was studied by routine light microscopy, special stains, immunohistochemical methods, and electron microscopy. Histologic examination showed a well-circumscribed nodule in the dermis composed of an intimate mixture of blood vessels, smooth muscle, and mature fat. These components were confirmed by special stains, immunohistochemistry, and electron microscopy. We concluded that the unique features of this lesion distinguish it from other lesions such as angiomyoma, angiolipoma, and other mixed mesenchymal tumors. This report demonstrates that the features considered diagnostic of angiomyolipoma can occur in extrarenal sites and, therefore, this diagnosis cannot be excluded on the basis of site alone.
SPERMATIC CORD
Angiomyolipoma of the spermatic cord: case report and literature review. Castillenti TA, Bertin AP. Department of Surgery, Doctors Hospital of Stark County Inc., Massillon, Ohio.	J Urol 1989 Nov;142(5):1308-9 Abstract quote A case of an extrarenal angiomyolipoma in the spermatic cord is presented. Angiomyolipomas are uncommon tumors usually found in the kidney. The common embryological origin of kidney and cord structures offers a theoretical basis for the occurrence of such a neoplasm at this remote site. Complete wide excision is curative and recurrences are infrequent.
SUBGALEAL
Subgaleal angiomyolipoma. Tamura A, Ishikawa O, Miyachi Y. Department of Dermatology, Gunma University School of Medicine, Japan.	J Dermatol 1994 Jul;21(7):514-7 Abstract quote A case of angiomyolipoma found in the subgaleal lesion is reported. Lipoma appearing between the galea and periosteum of the frontal bone is called subgaleal or subfascial lipoma and usually consists histopathologically of mature fat cells. We experienced a case of so-called subgaleal lipoma; however, the distinctive histologic features of our case were the proliferation of non-striated muscle fibers and small vessels scattered throughout the mature fat cells, which were compatible with angiomyolipoma. Extrarenal angiomyolipoma, especially cutaneous angiomyolipoma, are very rarely mentioned in the literature. Our case is the second reported patient with angiomyolipoma in the subgaleal location.
UTERUS
Uterine angiomyolipoma: case report and review of the literature. Yaegashi H, Moriya T, Soeda S, Yonemoto Y, Nagura H, Sasano H. Department of Pathology, Mitokyodo General Hospital, Mito, Japan.	Pathol Int 2001 Nov;51(11):896-901 Abstract quote Extrarenal angiomyolipomas (AML) have been reported at various anatomical sites, but infrequently in the gynecological region. In the uterus, only a few cases have been described. We describe a uterine angiomyolipoma occurring in a 40-year-old woman without evidence of tuberous sclerosis. The tumor arose on the right wall of the uterine body and was partially cystic, and it was associated with marked degeneration. It was composed of mature adipose tissue, anomalous blood vessels and non-vascular smooth muscle cells. Immunohistochemistry revealed that non- vascular smooth muscle cells were positive for alpha-smooth muscle actin (alpha-SMA), desmin, vimentin, antihuman muscle actin (HHF35) and progesterone receptor (PR), and negative for cytokeratin, antihuman melanoma (HMB45), CD34, S-100 and estrogen receptor (ER). It is of particular interest that non-vascular smooth muscle cells were negative for HMB45, in contrast to renal and other extrarenal AML in which HMB45 immunoreactivity has been demonstrated in these cells.
VAGINA
Angiomyolipoma of the vagina. Chen KT. Department of Pathology, Saint Agnes Medical Center, Fresno, California 93710.	Gynecol Oncol 1990 May;37(2):302-4 Abstract quote An angiomyolipoma arising in the vaginal apex and presenting as a pelvic mass is reported and compared with other reported cases of extrarenal angiomyolipoma. This case appears to be the second case of angiomyolipoma arising in the vaginal wall.

Disease Associations
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/Immunohistochemistry/Electron Microscopy
Differential Diagnosis
Prognosis and Treatment
Commonly Used Terms

DISEASE ASSOCIATIONS	CHARACTERIZATION
TUBEROUS SCLEROSIS

HISTOLOGICAL TYPES	CHARACTERIZATION
GENERAL	Similar to renal angiomyolipomas
VARIANTS
HIBERNOMA FEATURES
Extrarenal angiomyolipoma with melanocytic and hibernoma-like features. Liwnicz BH, Weeks DA, Zuppan CW. Department of Pathology, Loma Linda University, California 92354.	Ultrastruct Pathol 1994 Jul-Aug;18(4):443-8 Abstract quote Angiomyolipoma is a tumor commonly occurring in the kidney, but occasionally found in extrarenal sites. Retroperitoneal angiomyolipoma with unusual features presenting in a 39 year old woman with hypertension is reported in this paper. Tumor fat was inconspicuous, and present largely as hibernoma-like microvesicular lipid. Tumor cells also demonstrated positivity for HMB-45 and S-100 protein, and by electron microscopy showed occasional cytoplasmic striated granules indistinguishable from stage II premelanosomes. However, electron microscopy and immunocytochemistry also confirmed the presence of a substantial myogenous component in the tumor, establishing the diagnosis of angiomyolipoma. The implications of these findings, and the role of immunocytochemistry and electron microscopy in the diagnosis of this tumor are discussed.

SPECIAL STAINS/IMMUNOPEROXIDASE/ OTHER	CHARACTERIZATION
SPECIAL STAINS
IMMUNOPEROXIDASE	HMB45 positive
CD117
Expression of KIT (CD117) in Angiomyolipoma. Makhlouf HR, Remotti HE, Ishak KG. Department of Hepatic and Gastrointestinal Pathology, Armed Forces Institute of Pathology, Washington, DC, U.S.A.	Am J Surg Pathol 2002 Apr;26(4):493-7 Abstract quote Angiomyolipoma is a unique mesenchymal tumor postulated to arise from perivascular epithelioid cells. Immunohistochemical studies have shown that angiomyolipomas express the melanocytic markers HMB-45, MART-1 (Melan A), microphthalmia transcription factor, and tyrosinase, in addition to smooth muscle actin. KIT (CD117) is a transmembrane growth factor receptor expressed in cells of melanocytic and a variety of other cell lineages. To date, KIT immunoreactivity has not been systematically studied in angiomyolipoma. In this study we immunohistochemically analyzed a series of 21 angiomyolipomas (15 hepatic, six renal) with KIT. All were KIT positive: 14 of 21 (67%) with 3+ staining (>50% of tumor cells), 4 of 21 (19%) with 2+ staining (25-50% of tumor cells), and 3 of 21 (14%) with 1+ staining (<25% of tumor cells). In comparison, the percent of angiomyolipomas showing 3+ staining with HMB-45 was 62% and with Melan A was 52%. Positive KIT staining was detected in the epithelioid, spindle, and intermediate small round cells. Most cases showed diffuse cytoplasmic positivity. Strong perinuclear staining was present in the vacuolated clear epithelioid cells. There was focal KIT staining of fat cells. KIT was not detected in the endothelial cells lining blood vessels within the tumor. KIT may be a useful ancillary marker for the diagnosis of angiomyolipoma. A ngiomyolipoma should be included in the differential diagnosis of KIT-positive tumors.

PROGNOSIS AND TREATMENT	CHARACTERIZATION
PROGNOSTIC FACTORS
TREATMENT	Excision