A Case of Bing-Neel Syndrome Presenting Like Giant Cell Arteritis.

A 55-year-old woman presented with new-onset headache, scalp tenderness, shoulder arthralgias, night sweats, and loss of appetite. She was diagnosed with giant cell arteritis by her primary care physician and commenced on oral corticosteroids. However, her headache, scalp tenderness, and night sweats persisted. She then developed right Horner syndrome and trigeminal hypoesthesia. Extensive blood work-up revealed mildly elevated inflammatory markers and a paraproteinemia. Subsequent bone marrow biopsy showed lymphoplasmacytic lymphoma, with 10% of hemopoiesis, and staging led to the diagnosis of Waldenstrom macroglobulinemia without nodal or central nervous system (CNS) lesions. Immunohistochemical staining of a temporal artery biopsy showed perivascular lymphoplasmacytic cells and paraprotein deposits. She was diagnosed with CNS involvement of her macroglobulinemia-Bing-Neel syndrome (BNS). Identification of rare CNS involvement of lymphoma is challenging when a patient is already on steroid immunosuppression. In the absence of clear diagnostic criteria, the rare and heterogenous BNS remains a clinical diagnosis.