Trichofolliculoma

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Background

Trichofolliculoma represents an uncommon hamartoma of hair follicle tissue, typically occurring on the face of adults.


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Clinical appearance of trichofolliculoma.

The prognosis is excellent, and therapy is usually directed toward cosmetic improvement.

Pathophysiology

Although the precise etiology of trichofolliculoma is uncertain, these tumors are not associated with systemic disease or other skin disorders. Trichofolliculomas are believed to represent abortive differentiation of pluripotent skin cells toward hair follicles.

Epidemiology

Frequency

International

Trichofolliculoma represents an uncommon clinical entity.

Mortality/Morbidity

Trichofolliculomas are associated with minimal clinical morbidity; no confirmed cases of malignant transformation or clinical mortality are reported in the literature.

Race

In reported cases, trichofolliculomas demonstrate no definitive racial predilection.

Sex

No definitive sexual predilection is observed in reported cases, although sporadic reports indicate a probable male preponderance.

Age

From published reports, trichofolliculoma appears to primarily be a tumor of adults; however, at least 1 case of congenital trichofolliculoma has been reported.[1]

History

Patients typically present with a single, flesh-colored or whitish nodule or papule of varying duration, typically on the face (most frequently around the nose).

Physical

Causes

Histologic Findings

Following surgical excision, these tumors are found to consist of a dilated primary follicle lined by infundibular, stratified squamous epithelium and opening to the skin surface.[4]


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Low-power view of trichofolliculoma with a primary follicle opening onto the skin surface.

From the central follicle outward, numerous secondary and tertiary follicles can be observed, presenting at various levels of hair-follicle differentiation. Hair structures may be observed within the hair follicle lumen; small sebaceous elements may be found within the follicular units.


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Edge of the primary follicle with associated secondary and tertiary budding follicular structures.


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Higher magnification of budding follicular structures.

Minimal lymphocytic or granulomatous inflammation may be present. An abundant connective tissue stroma is also present surrounding the follicular structures.


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Low-power view of a section of trichofolliculoma demonstrating budding follicular structures and associated stroma.


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Higher magnification of budding follicular structures and associated stroma.

Abundant Merkel cells have been demonstrated within the follicular epithelium, supporting the concept that trichofolliculomas are hamartomas.[5]

A variant of the trichofolliculoma is the sebaceous trichofolliculoma, featuring similar histologic features, except for the presence of numerous well-differentiated sebaceous lobules emptying into the central, dilated primary follicle. Sebaceous trichofolliculoma demonstrates histologic overlap with folliculosebaceous cystic hamartoma.[6, 7] Some consider the latter tumor to be a sebaceous trichofolliculoma in telogen phase. A single case of trichofolliculoma with perineural invasion has been reported in the literature.[8]


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Higher magnification of central primary follicle and associated sebaceous lobules.

Surgical Care

Simple surgical excision is typically curative.

Prognosis

The prognosis is excellent. Although reports exist of recurrence at the primary site, these events are rare.

Author

Michael S Howard, MD, Dermatopathologist and Laboratory Director, Georgia Dermatopathology Associates

Disclosure: Nothing to disclose.

Coauthor(s)

Bruce R Smoller, MD, Executive Vice President, United States and Canadian Academy of Pathology

Disclosure: Nothing to disclose.

Specialty Editors

James W Patterson, MD, Professor of Pathology and Dermatology, Director of Dermatopathology, University of Virginia Medical Center

Disclosure: Nothing to disclose.

Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine; Consulting Staff, Mountain View Dermatology, PA

Disclosure: Nothing to disclose.

Rosalie Elenitsas, MD, Herman Beerman Professor of Dermatology, University of Pennsylvania School of Medicine; Director, Penn Cutaneous Pathology Services, Department of Dermatology, University of Pennsylvania Health System

Disclosure: Lippincott Williams Wilkins Royalty Textbook editor

Joel M Gelfand, MD, MSCE, Medical Director, Clinical Studies Unit, Assistant Professor, Department of Dermatology, Associate Scholar, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania

Disclosure: AMGEN Consulting fee Consulting; AMGEN Grant/research funds Investigator; Genentech Grant/research funds investigator; Centocor Consulting fee Consulting; Abbott Grant/research funds investigator; Abbott Consulting fee Consulting; Novartis investigator; Pfizer Grant/research funds investigator; Celgene Consulting fee DMC Chair; NIAMS and NHLBI Grant/research funds investigator

Chief Editor

Dirk M Elston, MD, Director, Ackerman Academy of Dermatopathology, New York

Disclosure: Nothing to disclose.

References

  1. Ishii N, Kawaguchi H, Takahashi K, Nakajima H. A case of congenital trichofolliculoma. J Dermatol. Mar 1992;19(3):195-6. [View Abstract]
  2. Cole P, Kaufman Y, Dishop M, Hatef DA, Hollier L. Giant, congenital folliculosebaceous cystic hamartoma: a case against a pathogenetic relationship with trichofolliculoma. Am J Dermatopathol. Oct 2008;30(5):500-3. [View Abstract]
  3. Wu YH. Folliculosebaceous cystic hamartoma or trichofolliculoma? A spectrum of hamartomatous changes inducted by perifollicular stroma in the follicular epithelium. J Cutan Pathol. Sep 2008;35(9):843-8. [View Abstract]
  4. Misago N, Kimura T, Toda S, Mori T, Narisawa Y. A revaluation of trichofolliculoma: the histopathological and immunohistochemical features. Am J Dermatopathol. Feb 2010;32(1):35-43. [View Abstract]
  5. Hartschuh W, Schulz T. Immunohistochemical investigation of the different developmental stages of trichofolliculoma with special reference to the Merkel cell. Am J Dermatopathol. Feb 1999;21(1):8-15. [View Abstract]
  6. Plewig G. Sebaceous trichofolliculoma. J Cutan Pathol. Dec 1980;7(6):394-403. [View Abstract]
  7. Tanimura S, Arita K, Iwao F, et al. Two cases of folliculosebaceous cystic hamartoma. Clin Exp Dermatol. Jan 2006;31(1):68-70. [View Abstract]
  8. Stern JB, Stout DA. Trichofolliculoma showing perineural invasion. Trichofolliculocarcinoma?. Arch Dermatol. Aug 1979;115(8):1003-4. [View Abstract]
  9. Gray HR, Helwig EB. Trichofolliculoma. Arch Dermatol. 1962;86:99-105.
  10. Headington JT. Tumors of hair follicle differentiation. In: Farmer E, Hood A, eds. Pathology of the Skin. New York, NY: McGraw-Hill; 1990:596-614.
  11. Kligman AM, Pinkus H. The histogenesis of nevoid tumors of the skin. The folliculoma--a hair-follicle tumor. Arch Dermatol. Jun 1960;81:922-30. [View Abstract]
  12. McKee P. Farmer E, Hood A, eds. Pathology of the Skin. 2nd ed. New York, NY: McGraw-Hill; 1996:15.25-15.28.
  13. Pinkus H, Sutton RL Jr. Trichofolliculoma. Arch Dermatol. Jan 1965;91:46-9. [View Abstract]
  14. Wick MR, Swanson PE, Barnhill RL. Sebaceous and pilar tumors. In: Barnhill R, ed. Textbook of Dermatopathology. New York, NY: McGraw-Hill; 1998:593-621.

Clinical appearance of trichofolliculoma.

Low-power view of trichofolliculoma with a primary follicle opening onto the skin surface.

Edge of the primary follicle with associated secondary and tertiary budding follicular structures.

Higher magnification of budding follicular structures.

Low-power view of a section of trichofolliculoma demonstrating budding follicular structures and associated stroma.

Higher magnification of budding follicular structures and associated stroma.

Higher magnification of central primary follicle and associated sebaceous lobules.

Low-power view of trichofolliculoma with a primary follicle opening onto the skin surface.

Edge of the primary follicle with associated secondary and tertiary budding follicular structures.

Higher magnification of budding follicular structures.

Low-power view of a section of trichofolliculoma demonstrating budding follicular structures and associated stroma.

Higher magnification of budding follicular structures and associated stroma.

Low-power view of sebaceous trichofolliculoma demonstrating dilated, primary follicle; budding follicular structures; and numerous associated sebaceous lobules.

Higher magnification of central primary follicle and associated sebaceous lobules.

Clinical appearance of trichofolliculoma.