Abstract
Collagenoma, also known as a solitary sclerotic fibroma, is a rare benign hamartomatous tumor that was recognized in 1972 by Weary et al. in a tongue biopsy specimen of a patient with Cowden syndrome.1 These tumors present clinically as an asymptomatic, firm, pink, white, or skin-colored dome-shaped papule or nodule that does not cause pain or discomfort. There are also reports of collagenomas having peau dorange-like appearance.3 They usually are found on the face, neck, and extremities, but can also appear on the trunk, scalp, and less frequently on the oral mucosa, nail bed, or nasolacrimal duct.1,4 These benign tumors occur in middle-aged people of both genders, but have a sight female predominance.4 Histopathological examination shows a well-circumscribed, unencapsulated hypocellular dermal proliferation composed of hyalinized collagen bundles arranged in a whorled or plywood-like pattern separated by clefts.1 Immunohistochemical analysis shows positivity for vimentin, factor XIIIa, collagen type 1, focal positivity for CD34, and positivity for epithelial membrane antigen (EMA) in slim, elongated fibroblasts.1,2 On dermoscopic evaluation this benign nevus presents with a structure-less white background surrounded by a delicate erythematous halo, short arborizing vessels, and focal areas with a thick yellowish scale.1 The pathogenesis of the collagenoma is controversial, but has been described by Rapini e Golitz to be caused by isolated injury when not associated with a syndrome.4 Its association with Cowden syndrome, tendency for recurrence, expression of cell proliferation markers such as proliferating cell nuclear antigen and Ki-67, and the evidence of synthesis of type I collagen support the concept that it is a fibrous tumor with active growth.1 We present a case of an isolated collagenoma in a teenage patient with no syndromic history.
Financial Disclosure:
No current or relevant financial relationships exist.
