Background

This is a rare adnexal proliferation that is considered a hamartoma, a focal malformation that resembles a neoplasm but is composed of an abnormal mixture tissue elements normally present at the site. It is thought to be derived from the hair disk or haarscheibe.

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
INCIDENCE/ PREVALENCE
AGE
SEX
GEOGRAPHY
EPIDEMIOLOGIC ASSOCIATIONS

 

DISEASE ASSOCIATIONS	CHARACTERIZATION
ACROCHORDONS
Multiple fibrofolliculomas with trichodiscomas and acrochordons. Fujita WH, Barr RJ, Headley JL.	Arch Dermatol. 1981 Jan;117(1):32-5 Abstract quote.   The syndrome of multiple fibrofolliculomas with trichodiscomas and acrochordons clinically is characterized by asymptomatic dome-shaped papules primarily involving the head, neck, chest, back, and arms. These tumors represent benign proliferations of the mesodermal and ectodermal components of the pilar apparatus. Substantial overlap between each of these lesions exists. Individual patients also exhibit a disease spectrum in which various tumors preponderate. The stimulus for this proliferation may be genetically determined, but the cause remains unknown. Merkel's cells were not identified in an electron microscopic study of a single trichodiscoma, but banded structures similar to those described in the closely related lesions of perifollicular fibroma and fibrous papule were seen.
BIRT-HOGG-DUBE SYNDROME

 

PATHOGENESIS

CHARACTERIZATION

 

LABORATORY/ RADIOLOGIC/ OTHER TESTS	CHARACTERIZATION
RADIOLOGIC
LABORATORY MARKERS

 

GROSS APPEARANCE/ CLINICAL VARIANTS	CHARACTERIZATION
GENERAL
Trichodiscoma. A benign tumor related to haarscheibe (hair disk). Pinkus H, Coskey R, Burgess GH.	Trichodiscoma. A benign tumor related to haarscheibe (hair disk).
VARIANTS
MULTIPLE
Familial multiple trichodiscomas. Camarasa JG, Calderon P, Moreno A. Department of Dermatology, Hospital del Mar, Autonomous University, Barcelona, Spain.	Acta Derm Venereol. 1988;68(2):163-5. Abstract quote     A familial multiple trichodiscoma involving two sisters is reported.   Trichodiscoma is a benign neoplasm of the mesenchymal component of the hair disk characterized clinically by asymptomatic papules and histologically by a dermal fibrovascular proliferation.   Familial involvement and associations with other follicular neoplasia should be investigated in all cases.

 

HISTOLOGICAL TYPES	CHARACTERIZATION
GENERAL
VARIANTS
SPINDLE CELL
Spindle Cell Predominant Trichodiscoma: A Fibrofolliculoma/Trichodiscoma Variant Considered Formerly to be a Neurofollicular Hamartoma: A Clinicopathological and Immunohistochemical Analysis of 17 Cases. Kutzner H, Requena L, Rutten A, Mentzel T. From the *Dermatopathologische Gemeinschaftspraxis, Friedrichshafen, Germany; and daggerFundacion Jimenez Diaz, Madrid, Spain.	Am J Dermatopathol. 2006 Feb;28(1):1-8. Abstract quote   Seventeen solitary nasal tumors that fulfilled all diagnostic criteria of so-called neurofollicular hamartoma, apart from distinct S100-positivity, were compared histopathologically and immunohistochemically with seven typical trichodiscomas from a similar clinical setting. Both the S100-negative neurofollicular hamartoma-like tumors and the trichodiscomas expressed an identical CD13-positive/CD34-positive fibrocytic immunophenotype without co-expression of neural/perineural (S100, neurofilament, epithelial membrane antigen), myogenic (desmin, calponin, muscle-specific actin, and alpha-smooth muscle actin), or melanocytic (S100, HMB45, NKI/C3, MelanA) epitopes. Histopathologically, there was striking morphologic overlap between trichodiscoma and S100-negative neurofollicular hamartoma-like tumor, apart from a highly characteristic fascicularly organized cellular fibrocytic stroma in the latter.   We conclude that fibrofolliculoma/trichodiscoma and neurofollicular hamartoma-like tumor are morphologic variants of a single hamartomatous entity in which neurofollicular hamartoma-like tumor occupies the cellular pole of the morphologic spectrum. The entity formerly known as neurofollicular hamartoma appears to be nothing but a particularly cellular trichodiscoma with a distinctively organized stroma composed of CD34-positive fibrocytes.   We therefore propose the new term spindle cell predominant trichodiscoma (SCPT) for this particular variant of the morphologic fibrofolliculoma/trichodiscoma spectrum.

 

SPECIAL STAINS/ IMMUNOPEROXIDASE/ OTHER	CHARACTERIZATION
SPECIAL STAINS
IMMUNOPEROXIDASE
CD34
CD34-reactive trichodiscoma. Chartier M, Reed ML, Mandavilli S, Fung M, M Grant-Kels J, Murphy M. Department of Dermatology, University of Connecticut Health Center, Farmington, CT, USA	J Cutan Pathol. 2004 May;31(5):398-400. Abstract quote   Background: Trichodiscomas are rare hamartomas of the dermal portion of the hair disc, a specialized component of the perifollicular mesenchyme. They are usually found as asymptomatic multiple skin-colored papules on the face and extremities and may have an autosomal dominant inheritance pattern. However, a solitary variant has been described. Case report: A 78-year-old woman presented with a single, non-pigmented, firm papule on the left tip of the nose, measuring 3.5 mm in diameter. Results: The histological examination revealed the previously described features of a trichodiscoma. The immunohistochemical analysis showed strong immunoreactivity for CD34 in the spindle cell component. Spindle cells were negative for S-100, HMB-45, Melan-A, EMA, neurofilament, desmin, and Factor XIIIa by immunohistochemistry. Conclusions: We report strong reactivity for CD34 in the spindle cell component of a trichodiscoma. We suggest that this lesion be considered in the differential diagnosis of any CD34(+) dermal spindle cell proliferation, in which an adjacent epithelial component cannot be entirely excluded.
ELECTRON MICROSCOPY

 

DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
NEUROFOLLICULAR HAMARTOMA
Neurofollicular hamartoma: a light microscopic and immunohistochemical study. Barr RJ, Goodman MM. Department of Dermatology, University of California, Irvine.	J Cutan Pathol 1989 Dec;16(6):336-41 Abstract quote Neurofollicular hamartoma is an unusual, previously undescribed neoplasm characterized by a proliferation of spindle cells and hyperplastic pilosebaceous units. Five cases were reviewed. The lesions presented as single, asymptomatic, smooth, flesh-colored papules. Four were on the nose, and one on the adjacent nasolabial fold. Immunoperoxidase studies performed on two cases utilizing antibodies to S-100 antigen were positive in both. These lesions share some histological and clinical features with angiofibroma and neurofibroma.

 

PROGNOSIS

CHARACTERIZATION

 

TREATMENT	CHARACTERIZATION
GENERAL

Henry JB. Clinical Diagnosis and Management by Laboratory Methods. Twentieth Edition. WB Saunders. 2001.
Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
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. 6th Edition. McGraw-Hill. 2003.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.

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Last Updated February 22, 2006

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