Tubercular Meningitis and Lymphadenitis Mimicking a Relapse of Burkitt's Lymphoma on (18)F-FDG-PET/CT: A Case Report.

Tuberculosis (TB) can present with various forms and can occasionally be mistaken for malignancy. Hereby, we report a 53-year-old man diagnosed and treated for Burkitt's lymphoma in 2009 who achieved a complete remission confirmed by a computed tomography (CT) scan. During the follow-up 2 years later, he complained of left hip pain that warranted investigation with magnetic resonance imaging and whole-body (18)F-fludeoxyglucose-positron emission tomography (FDG-PET)/CT which showed a benign lesion in the left hip associated with multiple lymph nodes in the chest and abdomen not amenable for biopsy. A follow-up PET/CT scan a few months later showed intense tracer uptake in the lymph nodes with size progression and appearance of new lymph nodes suspicious of lymphoma relapse. The patient was asymptomatic, and all investigations including viral and connective tissue disease studies were negative. Also the tuberculin skin test and QuantiFERON were negative. Lymph node biopsy was planned; however, the patient presented a few days earlier with fever, headache and photophobia. Cerebrospinal fluid (CSF) examination confirmed meningitis with lymphocytic pleocytosis and elevated protein. The CSF Gram stain, culture, viral and acid-fast bacilli were negative. CSF flow cytometry and cytopathology confirmed polyclonal lymphocytosis and suggested reactive causes. CSF TB culture grew Mycobacterium tuberculosis. Mediastinal lymph node biopsy also confirmed TB lymphadenitis. Four antituberculosis drugs were started. One year later, a PET/CT scan showed regression of all the involved lymph nodes. This case highlights the importance of excluding TB in patients with suspected malignancy, especially if they belong to endemic regions, and the increasing role of (18)F-FDG-PET/CT in the early detection of extrapulmonary TB.