This rare, histologically distinctive, and histogenetically enigmatic sarcoma with a compartmental pattern, having a predilection for children and young adults, originally was described by Christopherson, Foote, and Stewart in Memorial Sloan-Kettering Cancer Center in 1952. Previously this tumor was often considered a peripheral example of a nonchromaffin paraganglioma or an organoid variant of malignant granular cell tumor. There is no normal cell counterpart known to this tumor.

CLINICAL FEATURES OF ALVEOLAR SOFT PART SARCOMA IN SOFT TISSUE

Alveolar soft part sarcoma (ASPS) is a very rare tumor, constituting <1% of all soft tissue sarcomas (0.8%–0.9%) in two tertiary center series, including one from a large cancer hospital. Based on Armed Forces Institute of Pathology (AFIP) statistics from >250 patients, 39% of the cases occur in patients younger than the age of 20 years. Childhood examples have a female predominance, whereas those in the adults >30 years have a predilection for men (Fig. 32.1), as was previously observed in one series.

ASPS occurs in a wide variety of soft tissue locations (Fig. 33.2). Based on AFIP data, more than one third of patients present with tumors in the lower extremity, especially the thigh and buttock. Childhood tumors are more common in the head and neck (especially tongue) and upper extremity, whereas examples in adults occur more often in the lower extremity and trunk wall. Ten percent of adult cases occur in visceral locations, most commonly in the gynecologic tract.