Fine needle aspiration cytology and core biopsy in the diagnosis of alveolar soft part sarcoma presenting with lung metastases. A case report.

BACKGROUND: Alveolar soft part sarcoma is a rare soft tissue tumor of uncertain origin usually affecting young adults. This neoplasm has early metastatic potential. Its cytologic features, particularly when presenting with metastases, have rarely been described. CASE: A 23-year-old male presented with shortness of breath and scapular pain. Routine chest roentgenograms revealed multiple lung nodules. Malignancy was established by percutaneous fluoroscopically guided fine needle aspiration on a lung nodule. Possible metastatic alveolar soft part sarcoma was suggested by cytology among few considerations in the differential diagnosis. Alveolar soft part sarcoma was confirmed by lung core biopsy and further supported by immunohistochemistry and electron microscopy. Tumor cells expressed muscle-specific actin and myoglobin, and contained diastase-resistant inclusions with periodic acid-Schiff stain. Ultrastructurally, peculiar, elongated intracytoplasmic crystalline bodies typical of this neoplasm were identified. A meticulous clinical search led to finding the primary tumor deeply located in the right posterior thigh. CONCLUSION: Aspiration cytology is a reliable, cost-efficient technique in the diagnostic workup of masses suspicious for malignancy.