Carcinocythemia-associated Microangiopathic Haemolysis

Carcinocythemia defined as the presence of circulating carcinoma cells in the peripheral blood identifiable on routine light microscopy is an extremely rare complication of widely disseminated and usually end-stage solid organ malignancies. Given the rarity of this entity, it can cause diagnostic challenges for pathologists interpreting the peripheral blood smear. Microangiopathic Haemolytic Anaemia (MAHA) has been reported in the literature in patients with carcinocythemia. The author reports a case of 57-year-old female with widely metastatic lobular breast carcinoma who presented with bleeding gums and worsening fatigue. Peripheral blood smear showed findings consistent with MAHA as well as numerous circulating adenocarcinoma cells. A bone marrow biopsy showed near-complete replacement of the marrow by metastatic carcinoma. This case brings to light the association of carcinocythemia with haemolysis. Given the high incidence of MAHA in carcinocythemia and the differential treatment, a careful screening of peripheral smears maybe warranted in patients with a known history of metastatic carcinoma and laboratory suspicion of haemolysis.