"Cutaneous glomangiosarcoma of the thigh in a female patient: a diagnostic challenge with broad diff erentials. Author Block: Anna Sarah Erem, Drazen M. Jukic."

Summary: Glomangiosarcomas typically arise from extradigital benign glomus tumors that may lack the typical symptomology pain, pinpoint tenderness, and hypersensitivity to cold and can be notoriously hard to suspect clinically. The diagnosis remains histological with broad consideration of differentials. Although data is limited, wide local excision remains the treatment of choice as glomangiosarcomas may display aggressive behavior; recurrence, local invasion, and rare metastasis have been reported. We present the case of a 56-year-old female with a 6 mm red, erythematous papule with central scaling on the lateral thigh and pinpoint tenderness for several months (Figure 1, A). The clinical differential included basal cell carcinoma versus angioma. A shave biopsy (Figure 1, B-C) demonstrated bland, basophilic, uniform, round cells with punched- out nuclei at the rim of the lesion and a distinct central area of similar morphology with high-grade cytology of cells presented in solid sheets and increased mitotic activity (6 per 50 HPF). The histological differential diagnoses included primary cutaneous lesions, soft tissue, including vascular, neuroendocrine, and metastases. The malignant tumor cells were positive for CD34, SMA (Figure 1, D), Collagen IV, Cyclin D1, p16, PRAME, and negative for cytokeratin, neuroendocrine, and other melanocytic markers. The morphological impression and ancillary workup supported a malignant glomus tumor diagnosis. Glomangiosarcoma is an important diagnostic consideration, due to its aggressive behavior and metastatic potential. Punch or excisional biopsies are preferable, especially for cases with more classic presentation. Clinical history remains paramount for timely diagnosis. Our patient is scheduled for a complete excision and increased surveillance