Background: The F-18 fluorodeoxyglucose positron emission/computed tomography (FDG PET/CT) has become an established diagnostic imaging for malignancy. However, there are other diseases that can also be identified with FDG, some of them are infections such as tuberculosis. Case presentation: In this case report, two patients showed multiple hypermetabolic tuberculosis lesions on FDG PET/CT, with one of the patients having history of malignancy. The objective of the present case report is to emphasize the need to use other differential diagnosis techniques for tuberculosis especially in tuberculosisendemic countries when interpreting FDG PET/CT. Conclusion: By analyzing diagnostic imaging alone, there is a high chance of misinterpreting asymptomatic tuberculosis patient as having malignancy. Therefore, there is need for correlation with clinical data as well as other imaging modalities and PET/CT with more specific tracer in order to differentiate malignancy from benign disease such as tuberculosis.

Introduction: Lymphoma and tuberculosis in several cases share similar clinical features that are difficult to differentiate. Lymphadenopathy, fever, malaise, weight loss, and respiratory symptoms are clinical features that could be found in both lymphoma and tuberculosis. Positron Emission Tomography/Computed Tomography Fluorodeoxyglucose (F-18 FDG PET) is a pivotal modality for imaging patients with cancer. Several non-malignant diseases like tuberculosis infection show high FDG uptake and lead to low specificity of F-18 FDG PET.Case Presentation: This case report describes a 55-year-old male patient with a history of Diffuse Large B-cell Lymphoma (DLBCL) who was suspected of having a recurrent disease. The patient has had a 6-month remission period after 6 cycles of R-CHOP regimen chemotherapy. He denied any known history of tuberculosis infection and HIV. F-18 FDG PET was performed to assess the extent of suspected lymphoma recurrent disease. F-18 FDG PET demonstrated multiple hypermetabolic bilateral neck region, mediastinum, and bilateral axilla lymphadenopathies. There were also multiple high FDG uptakes in the liver, mesocolon, and bones. The patient was suspected of having a lymphoma recurrent disease based on these findings. He underwent an excisional biopsy in the neck and was found to have lymphadenitis granulomatous disease from tuberculosis. Based on the histopathology finding, the patient received anti-tuberculosis drugs for 12 months and showed relief of signs and symptoms. F-18 FDG PET for anti-tuberculosis treatment evaluation revealed a complete metabolic response.Conclusion: Tuberculosis should be one of the differential diagnoses when a lymphoma recurrent disease is suspected. Clinical features, laboratory results, and imaging findings sometimes show similarities between lymphoma and tuberculosis. Histopathology evaluation is mandatory to confirm the diagnosis.

Lymphadenopaty is a common clinical finding with a broad differential diagnosis, with