Carcinocythemia. Report of two cases, one simulating a Burkitt lymphoma.

Carcinocythemia is a rare complication of metastatic carcinoma, characterized by the presence of carcinoma cells in the peripheral blood, which may mimic acute leukemia. Two cases are reported in which the patients developed carcinocythemia several years after being treated for carcinoma of the breast. Cytologic examination of peripheral blood smears in both cases showed the presence of numerous large abnormal cells; in one case the cells simulated those of a Burkitt lymphoma. Cytochemical and/or immunologic marker studies ruled out a hematopoietic origin of the malignant cells in both cases and confirmed a diagnosis of carcinocythemia. The rapidly fatal outcome observed in these two cases was in accordance with the poor prognosis usually encountered with this rare phenomenon.