Atypical fibroxanthoma associated with differentiated-type v
An 82-year-old woman with a history of vulvar lichen sclerosus and differentiated-type vulvar intraepithelial neoplasia (dVIN), presented at our gynecology unit for a painless, nonbleeding, 1 cm nodule on the right labium minus. The patient underwent an excisional biopsy of the vulva. Macroscopically, the lesion appeared as a solid, nonhemorrhagic, dome-shaped greyish-brown nodule of 1 cm in maximum diameter. Microscopic examination found an extensive mesenchymal intradermal proliferation of highly atypical cells, arranged in a haphazard or vaguely fascicular pattern, diffusely infiltrating the dermis without extension in the subcutis or involvement of skin appendages. The overlying epidermis showed a dVIN.

No lympho-vascular invasion was observed. Histologically, the tumor resembled an undifferentiated pleomorphic sarcoma (UPS) with pleomorphic spindle-shaped, round or histiocyte-like cells with scattered multinucleated giant cells. The tumor cells displayed large, irregular and hyperchromatic nuclei; prominent nucleoli; and abundant, eosinophilic, or foamy cytoplasm. Multinucleated giant cells also exhibited bizarre and atypical nuclei. The mean mitotic count was 7 mitoses per 10 high-power fields, with many atypical mitoses.

Secondary changes included focal hemorrhage with hemosiderin deposition, focal myxoid stroma, and mild chronic inflammatory infiltrate. The underlying dVIN was completely excised, and the adjacent skin showed features of lichen sclerosus. Immunohistochemically, tumor cells were positive for vimentin and for CD10, and negative for all low- and high-molecular-weight cytokeratins, EMA, p63, S100 protein, HMB-45, Melan-A, CD99, CD117, SMA, desmin, CD34, CD31, ERG, ALK protein, WT-1, calretinin, and CD68. P53 was overexpressed. Based on these findings, a final diagnosis of atypical fibroxanthoma of the vulvar skin was made. After the diagnosis, the patient was referred to our gynecology unit for follow-up, and she is currently alive with no evidence of disease 24 months after the excision.

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