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myxoid dermatofibrosarcoma protuberans

Tuesday 2 October 2007

The myxoid variant of dermatofibrosarcoma protuberans (DFSPs) is uncommon. It is defined as a DFSP with greater than 50% myxoid stroma.

Synnopsis

- sex ratio 1/1
- median age 40 years (range 9 months to 72 years)
- tumor size: from 1.5 to 11 cm (median 2.8 cm)
- most frequent sites: extremities, head and neck, trunk, anogenital region
- Gross: white/tan/gray to yellow, firm to gelatinous soft tissue masses
- tumor stroma: from 50 to 100% myxoid (median 80%)
- infiltrative sheet-like proliferation of bland spindle cells with palely eosinophilic cytoplasm
- stellate nuclei without pleomorphism
- stroma myxoid with prominent thin-walled vessels
- honeycomb infiltration of fat
- cellular areas more typical of DFSP
- +/- pigmented dendritic cells (Bednar variant)
- +/- areas of giant cell fibroblastoma
- rare progression to fibrosarcomatous DFSP
- Mitoses: from 0 to 5 per 10 high power fields

Immunochemistry

- CD34 + (95%)
- S100 -
- muscle markers -

Prognosis

- local recurrence
- no metastasis

See also

- myxoid tumors

References

- Reimann JD, Fletcher CD. Myxoid dermatofibrosarcoma protuberans: a rare variant analyzed in a series of 23 cases. Am J Surg Pathol. 2007 Sep;31(9):1371-7. PMID: 17721193