[512] Flat Pleomorphic Fibromas: Report of Three Cases of an Unusual Morphologic Variant of Pleomorphic Fibroma

AC Iuga, WD Patino, Y Chiou, P Abenoza, GJ Gottlieb. The Ackerman Academy of Dermatopathology, New York, NY; St.Luke's Roosevelt Hospital Center, New York, NY; South Florida Dermpath Diagnostics Laboratory, Pompano Beach, FL

Background: Pleomorphic fibromas of the skin are rare benign dermal neoplasms composed of spindle and stellate cells admixed with haphazardly arranged thickened collagen bundles. Some of these cells can be markedly atypical, exhibiting nuclear pleomorphism, hyperchromasia and occasional multinucleation. However, mitotic figures are exceedingly rare.
Design: In this report we describe three cases of an unusual morphologic variant of pleomorphic fibroma.
Results: All three patients were middle-aged women who presented with predominantly flat dermal lesions with an infiltrative growth pattern, in contrast to the typically reported polypoid or dome-shaped lesions. In two of the cases the unusual histological presentation was coupled with the presence of prominent cellular pleomorphism and deep nodular lymphocytic infiltrates, raising the specter of desmoplastic melanoma. However, the discrepancy between the marked cellular atypia and the lack of prominent mitotic figures, as well as the absence of any other morphological findings suggestive of melanoma were helpful hints in the diagnosis.
Conclusions: Recognizing unusual flat variants of pleomorphic fibroma from infiltrative cutaneous malignant neoplasms is of utmost importance and has major implications for treatment and prognosis. Pleomorphic fibromas are benign in behavior and complete excision is usually curative. Local recurrences are rare and systemic spread has not been reported. Immunohistochemical studies have limited utility in recognizing these unusual variants and careful examination of the morphologic pattern remains the gold standard for diagnosis.
Category: Dermatopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 105, Wednesday Afternoon

 

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