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Skin - Nonmelanocytic tumors

Other tumors of skin

Pleomorphic fibroma

Reviewer: Christopher Hale, M.D. (see Reviewers page)
Revised: 18 September 2012, last major update September 2012
Copyright: (c) 2001-2012, PathologyOutlines.com, Inc.


● Polypoid or dome-shaped cutaneous nodule with sparse cellularity and cytologic atypia of fibroblasts
● Not a WHO diagnosis
● First described in 1989 (Am J Surg Pathol 1989;13:107)
● Usually trunk, extremity or head (Clin Exp Dermatol 1998;23:22)

Case reports

● 66 year old woman with subungual tumor (J Cutan Pathol 2003;30:569)

Micro description

● Resembles fibroepithelial polyp but with enlarged, bizarre, smudged, hyperchromatic nuclei, thick collagen bundles and rare mitotic figures
● May be sclerotic (Am J Dermatopathol 2002;24:54) or have myxoid foci (Am J Dermatopathol 1998;20:502)

Micro images

Large pleomorphic cells separated by collagen

Atypical cells have smudged chromatin, no/rare mitosis, no atypical mitotic figures, nuclei may be degenerative but not abnormal

Various images

Anal skin #1, #2

Positive stains

● Vimentin, actin, CD34

Negative stains

● S100

Differential diagnosis

● Atypical fibrous histiocytoma: more cellular, foam cells, hemosiderin laden macrophages (Am J Dermatopathol 1999;21:414)
● Atypical fibroxanthoma: more cellular, more mitotic figures
● Giant cell fibroblastoma: young children

End of Skin - Nonmelanocytic tumors > Other tumors of skin > Pleomorphic fibroma

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