LAUSR

A 74-year-old man was referred from another hospital with a possible incarcerated hernia after presenting with nausea, vomiting, weight loss and an umbilical protuberance (top left). His past medical history included chronic lymphocytic leukaemia (CLL) treated with fludarabine, cyclophosphamide and rituximab (FCR) chemo-immunotherapy 4 years earlier. Staging computed tomography/positron emission tomography (CT/PET) on arrival at our institution demonstrated extensive, highly F-fluorodeoxyglucose (FDG)-avid lymphadenopathy above and below the diaphragm and extranodal disease in the right anterior chest wall, omentum and peritoneal soft tissue as well as a large mesenteric nodal mass in direct communication with a large para-umbilical mass (Sister Mary Joseph nodule)(bottom left). Excisional biopsy of a right inguinal lymph node confirmed diffuse large B-cell lymphoma. Immunohistochemistry showed a germinal centre subtype and a ‘triple expressor’ phenotype (BCL6, BCL2 and MYC positive) with a proliferation fraction (Ki67) of greater than 90%. A diagnosis of Richter syndrome presenting as a Sister Mary Joseph nodule was made. He was treated with dose adjusted rituximab, etoposide, prednisolone, vincristine, cyclophosphamide and doxorubicin (DA-R-EPOCH) resulting in complete resolution of the umbilical nodule clinically and radiologically (top and bottom right). Sister Mary Joseph (peri-umbilical) nodule is a rare clinical sign, most commonly associated with gastrointestinal or genitourinary malignancy where it occurs in 1–3% of cases. When present, it generally reflects advanced malignancy unsuitable for resection and carries a bleak prognosis. Richter syndrome refers to the development of an aggressive B-cell lymphoma in the setting of underlying CLL, this occurring in up to 10% of CLL cases and carrying a poor prognosis. This case highlights the importance of considering lymphoma in the differential diagnosis of umbilical mass lesions.