Cytopathology of alveolar soft part sarcoma: a report of 10 cases

Alveolar soft part sarcoma (ASPS) rarely is subjected to cytopathologic evaluation. With the exception of some very small series, the literature is limited to case reports. The objectives of the current study were to evaluate the cytomorphology of 10 ASPS cases on fine-needle aspiration (FNA) or imprint cytology, review the literature, and highlight potential diagnostic pitfalls.

The authors searched their files for all lesions that were signed out as ASPS or suspicious for ASPS and searched the surgical pathology files for any cases of ASPS that had corresponding cytology. FNA was performed using the standard technique. Scrape preparations were performed on tissues that were sent fresh for frozen section examination.

Ten cases of ASPS were retrieved from 7 patients (male-to-female ratio, 4:3; mean age, 22 years). All had subsequent tissue confirmation. Six specimens were from primary lesions, 3 specimens were from metastases, and 1 intraoperative smear was from a previously aspirated primary mass in a newly diagnosed patient. Anatomic sites of involvement included extremities (5 specimens), trunk/pelvis (3 specimens), oral cavity (1 specimen), and lung (1 specimen). Eight specimens were aspirates, and 2 specimens were intraoperative smears. Nine cases were diagnosed correctly as ASPS/consistent with ASPS, and 1 specimen was diagnosed as "tumor, not otherwise specified". Cytomorphology included variably cellular smears composed of large cells with an enormous amount of finely granular or vacuolated cytoplasm, markedly enlarged nuclei/nucleoli, and bare nuclei. The cytomorphology of some cases revealed a strong similarity to renal cell carcinoma, clear cell type.

The results of the current study indicated that ASPS has cytomorphology that overlaps with several other neoplasms, including renal cell carcinoma. Nonetheless, the morphologic features, when combined with the clinical presentation, radiologic findings, and ancillary testing, may allow for a specific diagnosis.