A rare case of atypical chronic lymphocytic leukaemia presenting as nephrotic syndrome.

Chronic lymphocytic leukaemia (CLL) is characterised by a lymphocytosis of mature-appearing clonal CD5+, CD23+ B lymphocytes. CLL cells arise from the bone marrow and infiltrate lymphoid tissues such as lymph nodes and spleen. Presentation is usually through discovery of lymphocytosis or lymphadenopathy. Unusual presentations, especially paraneoplastic syndromes are rare. Here, we describe a rare case presenting with severe nephrotic syndrome associated with the presence of a monoclonal protein in serum. Workup for suspected plasma cell dyscrasia led instead to the diagnosis of bone marrow infiltration by atypical CLL without lymphocytosis. Renal biopsy showed a glomerulonephritis that turned out to be paraneoplastic as it went into remission after treatment for CLL. Our case shows an unusual presentation of CLL and prompts for increased awareness of lymphoproliferative disorders in the context of seemingly unrelated conditions that may be paraneoplastic in origin. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.