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11 November 2010 – Case of the Week #190
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Case of the Week #190
A 60 year old woman with no previous history had an ellipse of skin submitted from her right cheek, with a clinical diagnosis of basal cell carcinoma.
What is your diagnosis?
Storiform collagenoma, first described in 1991 (Am J Dermatopathol 1991;13:122), is a well circumscribed, hypocellular lesion with focal, heavy collagen deposition in a distinctive interweaving, storiform pattern, with prominent elongated clefts between the collagen bundles. Multinucleated giant cells have been described (Am J Surg Pathol 1998;22:557). Solitary lesions are also called sclerosing fibroma.
Storiform collagenoma usually occurs in young and middle aged adults, and presents as a slow growing solitary nodule up to 1 cm on the head, neck or upper extremities. It may be solitary, but multiple nodules are associated with Cowden's disease (eMedicine), a rare, autosomal dominant disorder with multiple hamartomatous neoplasms of ectodermal, mesodermal and endodermal origin; an increased risk of breast, thyroid or endometrial carcinoma; and disorders of the CNS, musculoskeletal system, GI system and female genital tract. Rarely, storiform collagenoma may be the presenting feature of Cowden's disease (J Clin Pathol 2007;60:840). Cowden's disease is considered part of the spectrum of various disorders with mutations in the PTEN gene, which collectively are termed PTEN hamartoma tumour syndrome.
The nodular stells are often immunoreactive for CD34 and vimentin, with prominent reticulin fibers. Scattered dendritic cells are factor XIIIa positive. The nodules are negative for keratin, EMA, CEA and elastic stains.
The differential diagnosis includes dermatofibroma, which has infiltrative margins, pseudoepitheliomatous hyperplasia and foamy histiocytes, and diffuse factor XIIIa staining. Sclerotic lipoma may appear similar, but has a variable number of S100+ and fat stain+ adipocytes interspersed within the fibrosclerotic stroma (Histopathology 1997;31:174). Perineurioma is composed primarily of perineurial cells, but may occasionally appear similar. It demonstrates variable CD34 staining, but is also typically EMA positive and S100 negative (Am J Surg Pathol 2005;29:845.)
These tumors have benign behavior, and no treatment is necessary. Solitary tumors may be excised for cosmetic reasons.
Nat Pernick, M.D., President
and Liz Parker, B.A., Associate Medical Editor
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