Waldenström's macroglobulinemia masquerading as ovarian cancer with peritoneal carcinomatosis, ascites, and elevated CA-125

Waldenström's macroglobulinemia is a rare hematology malignancy which often presents with “B symptoms,” anemia, and thrombocytopenia. A 46-year-old woman presented with 2 months of abdominal distension accompanied by an unintentional 20-lb weight loss. Her abdominal CT scan demonstrated diffuse carcinomatosis with bilateral ovarian lesions and screening labs revealed a markedly elevated CA-125, suggesting a diagnosis of ovarian cancer. Upon admission for workup, patient was found to have a significant protein gap, later attributed to a markedly elevated IgM. Omental and bone marrow biopsy confirmed the diagnosis of Waldenström's macroglobulinemia, with elevation in CA-125 thought to be secondary to peritoneal irritation. This patient has since been successfully treated with six cycles of bendamusine and rituximab with no evidence of disease on staging scans and normalization of both CA-125 and IgM. To our knowledge, this is the first documented case of Waldenström's macroglobulinemia presenting with symptoms classically associated with ovarian cancer and demonstrates the importance of maintaining a broad differential when evaluating patients with abdominal carcinomatosis.