Microangiopathic haemolytic anaemia, myelonecrosis, and myeloma-like presentation in metastatic cancers.

Microangiopathic haemolytic anaemia (MAHA), myelonecrosis (MN), and(hypercalcemia, renal dysfunction, anaemia, and bone lesion) CRAB-like features mimicking multiple myeloma (MM) at initial presentation are rarely reported in metastatic/disseminated solid cancers, and these may pose diagnostic challenges and adversely impact the outcome. We describe three middle-aged males with stage IV disease involving bone marrow (BM): one each from poorly differentiated gastric (GC) and colorectal (CRC) cancers with bone lesions, hypercalcemia, MAHA, and MN, and the other from prostate neuroendocrine cancer (PNEC) with dominant CRAB-like features mimicking MM along with MAHA and MN. We also present a comprehensive review of all reported cases and series of MAHA-associated solid epithelial cancers, including GC, CRC, and PC, over the last 24 years (2000-2024). MAHA occurred concurrently in a high proportion of cases, whereas this marked the recurrence of cancer in up to one-third of the cases. CRAB-like features mimicking MM at presentation were rarely reported, the latter more frequently in association with haematolymphoid malignancies than epithelial cancers. Bone pain, BM metastasis with raised serum alkaline phosphatase (ALP), lactate dehydrogenase, and the presence of schistocytes in the peripheral smear were more common. MAHA was associated with inferior median overall survival [3 to 10.5 months for GC and PC, respectively]. Early recognition of MAHA-associated complications and aggressive cancer-directed chemotherapy are essential for better patient care.