A 55-year-old man requests removal of a lesion affecting the vermilion border of his left lip commissure. The growth has been gradually enlarging in size over a one-year period and is asymptomatic. He denies prior history of verrucae and skin cancer; his father had a melanoma. He smokes cigarettes and is a social drinker. Examination reveals a 0.4 cm flesh-colored papule with a slightly hyperkeratotic crust.
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Biopsy revealed a lobular epidermal growth extending into the dermis; the growth contained vacuolated cells and coarse hyaline granules indicative of a tricholemmoma. This tumor was first described in 1962 as a benign neoplasm with differentiation toward the outer root sheath of the hair follicle.1 Tricholemmoma presents as a solitary papule that is either smooth or verrucoid in texture and is most commonly found on the face. Size ranges from 1 to 5 cm in diameter. A causal relationship to the human papilloma virus has been postulated.2 Individual lesions respond to simple shave excision; if recurrence is of concern, full excision is curative.
Benign in nature, the significance of tricholemmomas is their association with Cowden disease. Cowden, or multiple hamartoma, syndrome is an autosomal dominant disorder characterized by cutaneous and oral hamartomas as well as internal tumors. Patients are at a high risk of breast, thyroid, endometrium, and renal cancers.3 The genetic basis for Cowden syndrome is a mutation in the phosphatase and tensin homolog (PTEN) gene, a tumor suppressor that encodes a phosphatase that regulates cell cycle, cell migration, angiogenesis, and apoptosis.4
Jamie LaPorte, PA-C, is a physician assistant at Reading Dermatology Associates in Reading, Pennsylvania, and Stephen Schleicher, MD, is an associate professor of medicine at the Commonwealth Medical College in Scranton, Pennsylvania, and an adjunct assistant professor of dermatology at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia. He practices dermatology in Hazleton, Pennsylvania.
- Headington JT, French AJ. Primary neoplasms of the hair follicle. Histogenesis and classification. Arch Dermatol. 1962;86:430-441.
- Rohwedder A, Keminer O, Hendricks C, Schaller J. Detection of HPV DNA in trichilemmomas by polymerase chain reaction. J Med Virol. 1997;51(2):119-125.
- Eng C. Cowden syndrome. J Genet Counsel. 1997;6(2):181-192.
- Marsh DJ, Kum JB, Lunetta KL, et al. PTEN mutation spectrum and genotype-phenotype correlations in Bannayan-Riley-Ruvalcaba syndrome suggest a single entity with Cowden syndrome. Hum Mol Genet. 1999;8(8):1461-1472.