Hypercalcaemia, renal dysfunction, anaemia and bone lesions (CRAB) do not always represent multiple myeloma: diffuse large B cell lymphoma presenting with CRAB symptoms in a 69-year-old man

Abstract

Hypercalcaemia, renal dysfunction, anaemia and bone lesions (CRAB) are a constellation of signs and symptoms that are collectively referred to as the CRAB features. When present together, multiple myeloma (MM) should be at the top of the differential diagnosis. We present a 69-year-old man who presented with severe body aches and bone pain in his ribs and pelvis, associated with fatigue and constipation. He was found to have hypercalcaemia, acute kidney injury, anaemia and numerous lytic lesion on chest imaging. Physical examination and imaging were unremarkable for any enlarged lymph nodes. The patient was initially suspected to have multiple myeloma, however, serum and urine protein electrophoresis, and serum free light chain assays were negative. The patient was ultimately diagnosed with diffuse large B cell lymphoma based on a bone marrow biopsy. This case highlights the fact that presence of hypercalcaemia, renal dysfunction, anaemia and bone lesions are not usually specific for MM.