Alveolar rhabdomyosarcoma: a cytogenetic and correlated cytological and histological study.

A correlative, histologic and cytologic study of seven cases of alveolar rhabdomyosarcoma and chromosome analysis using the G-banding technique (in case 1) is presented. The histologic pattern was characterized by pseudo-alveolar structures, separated by fibrous septa. Primitive, dark, round cells predominated, but differentiated rhabdomyoblasts were found in all cases, and so were multi-nucleated giant cells. Unequivocal cross striation was seen in two cases. Cytologically, the tumors were highly cellular and small, undifferentiated tumor cells predominated. Large polymorphous, sometimes multi-nucleated, cells often with an elongated cytoplasm and eccentric nucleus were observed in all cases. The cell-types found could be well correlated to those identified in the histologic sections. The cytogenetic study revealed a karyotype profile, showing three 2q markers and only one chromosome type No. 13. The observations are different from the karyotype profile of embryonal rhabdomyosarcoma. However, further studies are necessary to elucidate this question.