We describe the cautionary case of a patient with advanced-stage large B-cell lymphoma (DLBCL). After combination chemotherapy, CT-PET revealed a persistent focus of likely DLBCL for which he received radiotherapy. Follow-up CT-PET showed diffuse hypermetabolic adenopathy and recurrent DLBCL was presumed. As part of clinical trial assessment, multiple biopsies showed non-caseating lymphadenitis consistent with sarcoidosis. No treatment for asymptomatic sarcoidosis was required and 18 months later he remains cancer-free. The presentation of sarcoidosis masquerading as recurrent DLBCL highlights the importance of tissue sampling prior to engaging in toxic and potentially life-threatening chemotherapy and the interesting link between DLBCL and sarcoidosis.