18F-FDG PET/CT findings in a mucosa-associated lymphoid tissue lymphoma patient coexisting with primary myelofibrosis.

A 61-year-old male presented with hematemesis and melena. Biopsy and immunohistochemistry confirmed mucosa-associated lymphoid tissue (MALT) lymphoma in the posterior wall of the gastric antrum, prompting further evaluation with 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT). In addition to elevated uptake in the gastric antrum, 18F-FDG PET/CT showed diffuse uptake in multiple bone marrow, initially suspected to indicate bone marrow involvement by lymphoma. Further examination identified it as primary myelofibrosis (PMF). Following concurrent therapies, 18F-FDG PET/CT demonstrated negative uptake in gastric antrum, indicating complete remission of the lymphoma, while the elevated bone marrow uptake suggested progression of PMF. The coexistence of MALT lymphoma and PMF is very rare. This case highlights the image characteristics and potential diagnostic and therapeutic monitoring value of 18F-FDG PET/CT in patients with concurrent MALT lymphoma and PMF.