Histiocytic medullary reticulosis complicating chronic lymphocytic leukaemia: malignant or reactive?

We describe 4 patients with a haemophagocytic syndrome resembling histiocytic medullary reticulosis (HMR) complicating chronic lymphocytic leukaemia (CLL) of 9 months to 8 years duration. Surface marker studies in 2 cases showed that the CLL lymphocytes were of B-cell type in one and of T-cell type in the other. 2 of the patients had histiological evidence of co-existing immunoblastic sarcoma at the time of diagnosis of the HMR-like syndrome and all 4 patients died within 3 weeks of this diagnosis. The pathogenesis of the HMR-like syndrome in these patients is discussed and it is concluded that it is probably reactive to an underlying opportunistic viral function related to their immunodepressed state secondary to CLL and/or the cytotoxic therapy.