Diffuse Large B-Cell Lymphoma With a Background of Extensive Granulomatous Inflammation: A Potential Pitfall for Misdiagnosis.

Granulomatous inflammation has been reported to be associated with Hodgkin and non-Hodgkin lymphomas. Here, we report a case of recurrent diffuse large B-cell lymphoma (DLBCL) with extensive granulomatous inflammation that was initially misdiagnosed as granulomatous lymphadenitis. In 2019, a 75-year-old Caucasian male presented to our hospital with an enlarged right supraclavicular lymph node. He had a medical history of prostate cancer (in 2004), DLBCL (initially diagnosed in 2009), and rectal adenocarcinoma (in 2017), all of which responded well to treatment. In 2018, the patient had experienced right axillary adenopathy, weight loss, and intermittent night sweats. An excisional biopsy of a right axillary lymph node, performed at another institution, was diagnosed as granulomatous lymphadenitis. In 2019, at our hospital, an excisional biopsy of a right supraclavicular lymph node showed DLBCL in a background of granulomatous inflammation. A review of the prior right axillary lymph node biopsy also showed DLBCL with a background of extensive granulomatous inflammation. Chemotherapy was initiated and the patient's follow-up showed a good response. We report this case to raise awareness that granulomatous inflammation may obscure the diagnosis of some neoplasms, such as DLBCL, which are less commonly known to have granulomatous inflammation. This may result in delayed treatment and may ultimately affect outcomes.