Mantle cell lymphoma (MCL) is a rare type of B-cell non-Hodgkin lymphoma that commonly presents with constitutional symptoms, lymphadenopathy, and laboratory abnormalities. Although less common, extranodal involvement of MCL may be seen at initial presentation and most commonly occurs in the spleen, liver, bone marrow, and gastrointestinal tract. Adrenal involvement in MCL is extremely rare, and only a few cases have been reported in the literature. Herein, we present 18F-FDG PET/CT and 68Ga-DOTATATE PET/CT findings of a unique case of primary extranodal MCL with gastric and adrenal involvement.