Skin nonmelanocytic tumor
Fibrous, fibrohistiocytic and myofibroblastic neoplasms
Pleomorphic fibroma
Last author update: 1 June 2013
Last staff update: 1 November 2023
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PubMed Search: Pleomorphic fibroma of skin
Table of Contents
Definition / general | Clinical features | Case reports | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Cytology images | Positive stains | Negative stains | Differential diagnosisCite this page: Jabcuga C. Pleomorphic fibroma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissuepleomorphicfibroma.html. Accessed March 31st, 2025.
Definition / general
- 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)
- Related entities: may be a variant of skin tag (acrochordon) with cytologic atypia
Clinical features
- Flesh-colored polyp resembling skin tag (acrochordon)
Case reports
- 38 year old woman with a flesh-colored forehead nodule (Arch Pathol Lab Med 2005;129:e21)
- 38 year old man (J Cytol 2013;30:71)
- 66 year old woman with subungual tumor (J Cutan Pathol 2003;30:569)
- 75 year old man with myxoid pleomorphic fibroma that supposedly progressed to myxofibrosarcoma (Australas J Dermatol 2003;44:287)
Microscopic (histologic) 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)
Microscopic (histologic) images
AFIP images
Large pleomorphic cells
Atypical cells
Images hosted on other servers:
Anal skin
Stromal cells have atypical nuclei
Cytology description
- Single lying and few clusters of pleomorphic cells with some monster cells and scant cytoplasm (J Cytol 2013;30:71)
Cytology images
Images hosted on other servers:
Pleomorphic cells with very large nuclei
Pleomorphic cells
scattered between
collagen bundles
Vimentin+
Negative stains
Differential diagnosis
- Angiofibroma: pleomorphic cells are similar, but have marked vascularity
- Atypical fibrous histiocytoma / dermatofibroma with monster cells: storiform pattern, more cellular, foam cells, hemosiderin laden macrophages, CD34- (Am J Dermatopathol 1999;21:414)
- Atypical fibroxanthoma: more cellular, more mitotic figures
- Atypical lipomatous tumor: may be in differential when pleomorphic fibroma has entrapped adipose cells, but atypical lipomatous tumor has 12q15/MDM2 amplification by FISH (J Cutan Pathol 2013;40:379)
- Dermal pleomorphic liposarcoma: high-grade sarcoma with pleomorphic lipoblasts (J Cutan Pathol 2013;40:734, Am J Surg Pathol 2012;36:1047)
- Giant cell fibroblastoma: young children
