Proliferating Pilar Tumor 

  • Author: Amor Khachemoune, MD, CWS; Chief Editor: William D James, MD   more...
 
Updated: Aug 16, 2011
 

Background

A proliferating pilar tumor (PPT) is a rare neoplasm arising from the isthmus region of the outer root sheath of the hair follicle. It is also commonly called a proliferating tricholemmal cyst. It was first described by Wilson-Jones[1] as a proliferating epidermoid cyst in 1966. PPT was then distinguished from proliferating epidermoid cysts in 1995.[2] It occurs most commonly on the scalp in women older than 50 years.[3] Most tumors arise within a preexisting pilar cyst. Even though they usually are benign in nature, malignant transformation with local invasion and metastasis has been described.[4, 5, 6] A tentative stratification of PPTs into groups as benign, low-grade malignancy, and high-grade malignancy has been introduced. They may be inherited in an autosomal-dominant mode, linked to chromosome 3. See Pilar Cyst for more information.

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Pathophysiology

A PPT usually arises in the setting of single or multiple pilar cysts. An asymptomatic nodule is often present for months to years before a rapid increase occurs in the size of the lesion. This is thought to signal neoplastic transformation of the cyst, with progression into a PPT. The underlying stimulus for this transformation is not known, but it has been hypothesized to be secondary to trauma, irritation, or chronic inflammation. In a review of 76 cases of PPTs seen in consultation from 1989-2000, Ye et al[7] proposed a distinction between benign and malignant variants. The authors also proposed histologic criteria that could predict behavior.

It is believed to be analogous to proliferating onycholemmal cyst, an entity that is even more rare in the literature.[8]

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Epidemiology

Frequency

United States

These tumors are rare.

Mortality/Morbidity

The lesions are usually painless. Exophytic growth with ulceration and foul-smelling discharge may occur. Some lesions may grow very large and cause pressure necrosis on underlying tissues, especially on the scalp. Local recurrence following excision and/or metastasis has been reported in rare instances in which malignancy has occurred. While proliferating pilar tumors may have varying levels of cellular atypia on histologic examination, there have been cases of squamous cell carcinomas diagnosed within proliferating pilar tumors, with only one reported case of squamous cell carcinoma progressing to distant nodal metastasis and death.[9]

Sex

These tumors occur more commonly in females than in males.

Age

PPTs are most common in older individuals aged 50-75 years, although they have been reported in individuals aged 20-30 years.

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Contributor Information and Disclosures
Author

Amor Khachemoune, MD, CWS  Mohs Micrographic Surgery, Dermatopathology, Department of Dermatology, State University of New York Downstate Medical Center; Consulting Staff, Department of Dermatology, Veterans Affairs Medical Center of Brooklyn

Amor Khachemoune, MD, CWS is a member of the following medical societies: American Academy of Dermatology, American Academy of Wound Management, American College of Mohs Micrographic Surgery and Cutaneous Oncology, American Medical Association, American Society for Dermatologic Surgery, and American Society for Laser Medicine and Surgery

Disclosure: Nothing to disclose.

Coauthor(s)

Steve A McClain, MD  Clinical Associate Professor, Department of Pathology, State University of New York at Stony Brook; Medical Director, Founder and Owner, McClain Laboratories LLC

Steve A McClain, MD is a member of the following medical societies: American Society for Clinical Pathology and College of American Pathologists

Disclosure: McClain Laboratories, LLC Ownership interest Management position

Rashid M Rashid, MD, PhD  Resident Physician, Department of Dermatology, University of Texas, Houston, MD Anderson Cancer Center, and Morzak Research Initiative

Rashid M Rashid, MD, PhD is a member of the following medical societies: American Academy of Dermatology, Council for Nail Disorders, Houston Dermatological Society, Texas Dermatological Society, and Texas Medical Association

Disclosure: Nothing to disclose.

Daniel Mark Siegel, MD, MS  Director, Procedural Dermatology Fellowship Program, Clinical Professor of Dermatology, Department of Dermatology, State University of New York Downstate

Daniel Mark Siegel, MD, MS is a member of the following medical societies: American Academy of Dermatology, American College of Mohs Micrographic Surgery and Cutaneous Oncology, American College of Physician Executives, American Society for Dermatologic Surgery, American Society for MOHS Surgery, and International Society for Dermatologic Surgery

Disclosure: Nothing to disclose.

Kimberly Silvers, MD, PhD  Staff Physician, Section of Dermatology, Guthrie Clinic

Kimberly Silvers, MD, PhD is a member of the following medical societies: American Academy of Dermatology and Phi Beta Kappa

Disclosure: Nothing to disclose.

Specialty Editor Board

R Stan Taylor, MD  The JB Howell Professor in Melanoma Education and Detection, Departments of Dermatology and Plastic Surgery, Director, Skin Surgery and Oncology Clinic, University of Texas Southwestern Medical Center

R Stan Taylor, MD is a member of the following medical societies: American Academy of Dermatology, American College of Mohs Surgery, American Dermatological Association, American Medical Association, American Society for Dermatologic Surgery, Christian Medical & Dental Society, and Society for Investigative Dermatology

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

Richard P Vinson, MD is a member of the following medical societies: American Academy of Dermatology, Association of Military Dermatologists, Texas Dermatological Society, and Texas Medical Association

Disclosure: Nothing to disclose.

John G Albertini, MD  Consulting Staff, Dermatologic Surgery, The Skin Surgery Center; Program Director, ACGME Accredited Fellowship in Procedural Dermatology

John G Albertini, MD is a member of the following medical societies: American Academy of Dermatology and American College of Mohs Micrographic Surgery and Cutaneous Oncology

Disclosure: Nothing to disclose.

Glen H Crawford, MD  Assistant Clinical Professor, Department of Dermatology, University of Pennsylvania School of Medicine; Chief, Division of Dermatology, The Pennsylvania Hospital

Glen H Crawford, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, Phi Beta Kappa, and Society of USAF Flight Surgeons

Disclosure: Nothing to disclose.

Chief Editor

William D James, MD  Paul R Gross Professor of Dermatology, University of Pennsylvania School of Medicine; Vice-Chair, Program Director, Department of Dermatology, University of Pennsylvania Health System

William D James, MD is a member of the following medical societies: American Academy of Dermatology and Society for Investigative Dermatology

Disclosure: Elsevier Royalty Other

References

  1. Wilson-Jones E. Proliferating epidermoid cysts. Arch Dermatol. 1966;94:11.

  2. Sau P, Graham JH, Helwig EB. Proliferating epithelial cysts. Clinicopathological analysis of 96 cases. J Cutan Pathol. Oct 1995;22(5):394-406. [Medline].

  3. López-Ríos F, Rodríguez-Peralto JL, Aguilar A, Hernández L, Gallego M. Proliferating trichilemmal cyst with focal invasion: report of a case and a review of the literature. Am J Dermatopathol. Apr 2000;22(2):183-7. [Medline].

  4. Mehregan AH, Lee KC. Malignant proliferating trichilemmal tumors--report of three cases. J Dermatol Surg Oncol. Dec 1987;13(12):1339-42. [Medline].

  5. Saida T, Oohara K, Hori Y, Tsuchiya S. Development of a malignant proliferating trichilemmal cyst in a patient with multiple trichilemmal cysts. Dermatologica. 1983;166(4):203-8. [Medline].

  6. Weiss J, Heine M, Grimmel M, Jung EG. Malignant proliferating trichilemmal cyst. J Am Acad Dermatol. May 1995;32(5 Pt 2):870-3. [Medline].

  7. Ye J, Nappi O, Swanson PE, Patterson JW, Wick MR. Proliferating pilar tumors: a clinicopathologic study of 76 cases with a proposal for definition of benign and malignant variants. Am J Clin Pathol. Oct 2004;122(4):566-74. [Medline].

  8. Alessi E, Zorzi F, Gianotti R, Parafioriti A. Malignant proliferating onycholemmal cyst. J Cutan Pathol. Apr 1994;21(2):183-8. [Medline].

  9. Eskander A, Ghazarian D, Bray P, Dawson LA, Goldstein DP. Squamous cell carcinoma arising in a proliferating pilar (trichilemmal) cyst with nodal and distant metastases. J Otolaryngol Head Neck Surg. Oct 2010;39(5):E63-7. [Medline].

  10. Wang X, Yang J, Yang W. Multiple proliferating trichilemmal tumors in a middle-aged yellow man. Tumori. Mar-Apr 2010;96(2):349-51. [Medline].

  11. Karaca S, Kulac M, Dilek FH, Polat C, Yilmaz S. Giant proliferating trichilemmal tumor of the gluteal region. Dermatol Surg. Dec 2005;31(12):1734-6. [Medline].

  12. Avinoach I, Zirkin HJ, Glezerman M. Proliferating trichilemmal tumor of the vulva. Case report and review of the literature. Int J Gynecol Pathol. 1989;8(2):163-8. [Medline].

  13. Kang SJ, Wojno TH, Grossniklaus HE. Proliferating trichilemmal cyst of the eyelid. Am J Ophthalmol. Jun 2007;143(6):1065-7. [Medline].

  14. Chang SJ, Sims J, Murtagh FR, McCaffrey JC, Messina JL. Proliferating trichilemmal cysts of the scalp on CT. AJNR Am J Neuroradiol. Mar 2006;27(3):712-4. [Medline].

  15. Gossner J, Larsen J. Incidental subcutaneous nodules on the scalp in patients undergoing CT of the brain; frequency, appearance, and differential diagnosis. Clin Radiol. May 2010;65(5):427-8. [Medline].

  16. Shet T, Modi C. Nucleolar organizer regions (NORs) in simple and proliferating trichilemmal cysts (pilar cysts and pilar tumors). Indian J Pathol Microbiol. Oct 2004;47(4):469-73. [Medline].

  17. Chaichamnan K, Satayasoontorn K, Puttanupaab S, Attainsee A. Malignant proliferating trichilemmal tumors with CD34 expression. J Med Assoc Thai. Nov 2010;93 Suppl 6:S28-34. [Medline].

  18. Masui Y, Komine M, Kadono T, Ishiura N, Maekawa T, Ihn H. Proliferating tricholemmal cystic carcinoma: a case containing differentiated and dedifferentiated parts. J Cutan Pathol. Oct 2008;35 Suppl 1:55-8. [Medline].

  19. Nyquist GG, Mumm C, Grau R, Crowson AN, Shurman DL, Benedetto P, et al. Malignant proliferating pilar tumors arising in KID syndrome: a report of two patients. Am J Med Genet A. Apr 1 2007;143(7):734-41. [Medline].

  20. Amaral AL, Nascimento AG, Goellner JR. Proliferating pilar (trichilemmal) cyst. Report of two cases, one with carcinomatous transformation and one with distant metastases. Arch Pathol Lab Med. Oct 1984;108(10):808-10. [Medline].

  21. Batman PA, Evans HJ. Metastasising pilar tumour of scalp. J Clin Pathol. Jul 1986;39(7):757-60. [Medline].

  22. Folpe AL, Reisenauer AK, Mentzel T, Rütten A, Solomon AR. Proliferating trichilemmal tumors: clinicopathologic evaluation is a guide to biologic behavior. J Cutan Pathol. Sep 2003;30(8):492-8. [Medline].

  23. Janitz J, Wiedersberg H. Trichilemmal pilar tumors. Cancer. Apr 1 1980;45(7):1594-7. [Medline].

  24. Kanitakis J, Bourchany D, Faure M, Claudy A. Expression of the hair stem cell-specific keratin 15 in pilar tumors of the skin. Eur J Dermatol. Jul-Aug 1999;9(5):363-5. [Medline].

  25. Mann B, Salm R, Azzopardi JG. Pilar tumour: a distinctive type of trichilemmoma. Diagn Histopathol. Jul-Sep 1982;5(3):157-67. [Medline].

  26. Mannan AA, Mirza K. Proliferating trichilemmal tumor in the chest wall: report of a rare case. Gulf J Oncolog. Jul 2008;(4):63-5. [Medline].

  27. Morgan RF, Dellon A, Hoopes JE. Pilar tumors. Plast Reconstr Surg. Apr 1979;63(4):520-4. [Medline].

  28. Plumb SJ, Argenyi ZB, Stone MS, De Young BR. Cytokeratin 5/6 immunostaining in cutaneous adnexal neoplasms and metastatic adenocarcinoma. Am J Dermatopathol. Dec 2004;26(6):447-51. [Medline].

  29. Poiares Baptista A, Garcia E Silva L, Born MC. Proliferating trichilemmal cyst. J Cutan Pathol. Jun 1983;10(3):178-87. [Medline].

 
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Proliferating trichilemmal cystic neoplasm. Well-circumscribed neoplasm with central cornified cells (2X). Courtesy of Steve A. McClain, MD.
Proliferating trichilemmal cystic neoplasm (20X). Courtesy of Steve A. McClain, MD.
Proliferating trichilemmal cystic neoplasm (400X). Note the pleomorphism of keratinocytes and mitotic figures. Courtesy of Steve A. McClain, MD.
 
 
 
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