Abstract Introduction/Objective Myxofibrosarcoma comprises a spectrum of malignant fibroblastic neoplasms with variably myxoid stroma, pleomorphism, and a distinctive curvilinear vascular pattern. Herein we describe a case of myxofibrosarcoma with unusual histological features that could be deceptive, mimic superficial angiomyxoma and make the diagnosis challenging Methods/Case Report A 74-year-old female presented with a right upper arm lesion that had been present for 10-12 months and had significantly increased in size over this time and became painful. There was no history of trauma. Examination demonstrated approximately 3 cm multinodular mass along the anterior aspect of the proximal arm. There were no overlying skin discolorations or ecchymosis. The patient underwent a shave biopsy and then resection. Grossly, the lesion was gray-white firm with an ill-defined border covered with a tan-white skin ellipse. Histologically, the lesion was located in the dermis extending to the dermal-epidermal junction. The lesion comprised mainly of myxoid stroma, arborizing, and plexiform thin-walled blood vessels, stellate to spindled cells with enlarged hyperchromatic nuclei, and eosinophilic cytoplasm in addition to the presence of stromal neutrophils and hyperplastic overlying squamous epithelium. The morphologic appearance elicited the differential diagnosis of superficial angiomyxoma and low-grade myxofibrosarcoma. While many features were more suggestive of superficial angiomyxoma, the degree of atypia and mitotic activity (12/10 HPF) was outside the realm of angiomyxoma and warranted the diagnosis of myxofibrosarcoma Results (if a Case Study enter NA) NA Conclusion Although rare, myxofibrosarcoma may rarely extend to the dermal-epidermal junction and mimic superficial angiomyxoma. The presence of cytologic atypia and increased mitotic activity favors myxofibrosarcoma
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