Fine-needle aspiration of alveolar soft part sarcoma: Histologic correlation and aberrant CD68 expression

Alveolar soft part sarcoma is a rare highly malignant neoplasm of the soft tissue and usually occurs in the lower extremities of children and young adults. We report two cases of alveolar soft part sarcoma: a 24-year-old Latino man with a 10-cm neck mass and a 56-year-old Latino woman with a recurring thigh mass. Fine-needle aspiration and a core biopsy were performed on both, which was followed by tumor resection on the man. The smears displayed numerous loosely cohesive or single large cells with abundant granular cytoplasm, round nuclei, vesicular chromatin, and occasional prominent nucleoli. Periodic and Schiff (PAS)-positive, diastase-resistant rhomboid, or needle-shaped crystals were present. Both tumors had diffuse and strong nuclear TFE3 expression and aberrant cytoplasmic CD68 expression. Fluorescence in situ hybridization analysis was performed in the first case, which detected a characteristic translocation t(X;17)(p11;q25). The diagnosis of alveolar soft part sarcoma was rendered in both cases. Herein, we present the cytology, histology, immunohistochemistry, and molecular findings and discuss the differential diagnosis.