Summary. We report four patients who either presented with or developed serous effusions during the course of monocytic leukaemia. This finding has not been documented previously. All the patients had very high peripheral blood monocyte counts when effusions developed. The effusions resolved after the patients were treated with anti-leukaemic therapy. It is therefore likely that the effusions were disease related. Two of the patients have been treated with raxoxane, one with eptoposide and the other with cytarabine.

Monocytic leukaemias comprise a spectrum of disorders ranging from acute monoblastic leukaemias (AMOL) and acute myelomonocytic leukaemia (AMML) to chronic myelomono-cytic leukaemias (CMML) (Shaw, 1980). Whereas leukaemic infiltration of the gums, central nervous system and skin is well recognized in AMOL and AMML, it is uncommon in CMML (Shaw, 19 78). In contrast to the lymphoid malignancies, leukaemic infiltration of the serosal surfaces giving rise to effusions is rare in both myeloid and monocytic leukaemias and has not been previously documented in CMML. We report four patients with monocytic leukaemia who developed either pleural and/or pericardial effusions or ascites which responded to anti-leukaemic therapy.