Effusion cytology of renal cell carcinoma

Effusions in patients with renal cell carcinoma are rare; the clinicopathologic features of these patients have not been described fully.

All effusions from patients with renal cell carcinoma obtained between 1986 and 1997 at the study institution were reviewed.

Twelve effusions from 9 patients were benign, and 8 effusions from 7 patients were malignant. Patients with sarcomatoid tumors presented early with benign effusions, and patients with papillary tumors presented later with malignant effusions. Patients with clear cell tumors were intermediate. The majority of patients who developed malignant effusions had tumors that were classified as T3 or higher (according to the American Joint Committee on Cancer) at the time of resection. Tumor cells had abundant clear to vacuolated cytoplasm, large nuclei, and prominent nucleoli. Cells from clear cell and papillary tumors could not be distinguished in effusion specimens unless papillae were present. At last follow-up 13 of 15 patients were dead of disease within 2 years of the onset of effusion (median 24 weeks; range, 1-93 weeks), including 7 of 9 patients with benign effusions.

Malignant effusions due to renal cell carcinoma most commonly occur in patients with papillary and clear cell tumors. Malignant effusions from these two tumor types are difficult to distinguish unless papillae are present. Effusions associated with renal cell carcinoma confer a poor prognosis.