Aspiration cytology of metastatic hypernephroma.

The findings in aspiration cytology smears from 15 patients with metastatic hypernephroma (renal-cell carcinoma) are presented along with the criteria for cytologic classification of aspirates of primary hypernephroma. The distinctive cytopathology of needle aspirates of metastatic lesions is illustrated. A small nuclear-cytoplasmic ratio was evident in poorly differentiated cells. The cytoplasm was highly characteristic, particularly with Romanovsky stains, and was termed "opaque with or without vacuolization and granulation" to distinguish it from the so-called clear cell of histopathology, which has been denuded of its cytoplasmic content by the histologic process. Cytoplasmic vacuoles were punched out, bubbly or lacy. The partially extruded nucleus was a useful identifying feature. In 7 of the 15 cases, primary hypernephroma was indicated by the cytologic findings in the metastases. This finding may be clinically useful in diagnosing the broad spectrum of obscure paraneoplastic syndromes that may accompany this tumor.