BMJ Case Rep. 2020 Oct 30;13(10):e235687. doi: 10.1136/bcr-2020-235687.
A 61-year-old man presented to the department of clinical haematology in February 2016 with symptomatic anaemia, generalised lymphadenopathy and hepatomegaly. Routine investigations showed severe anaemia with the presence of lymphoplasmacytoid cells in the peripheral smear, and bone marrow examination with IHC and serum protein electrophoresis confirmed diagnosis of lymphoplasmacytic lymphoma. The patient received supportive transfusion therapy and combination chemotherapy. After VI cycles, the
patient had a complete haematological response with marrow in remission. Maintenance rituximab was planned every 3 months for 2 years. At the time of first dose of maintenance rituximab, his haemoglobin (Hb) was 189 g/L with low normal erythropoietin level. During the last 3 years follow-up, his Hb ranged between 16.5 and 20.1 g/dL. All causes of secondary polycythaemia were ruled out. Workup for polycythAemia vera (PV), including JAK-2 and bone marrow, was not suggestive of PV. We labelled it as a case of polycythaemia due to undetermined aetiology.