Ambiguity of Whole Body PET CT Scans in Diagnosis of Co-existing Tuberculosis and Malignancy: Is Histopathological Confirmation Mandatory?

INTRODUCTION: Whole body PET CT is an important investigation tool in malignancy patients and helps in ascertaining the metabolic activity and exact stage of the disease. However, like any other investigation, false positive results do exist and certain diseases other than cancer may show increased uptake. Hence, a careful evaluation of PET CT and clinical correlation in malignancy patients is a must to accomplish the suitable treatment.

METHODS: In this retrospective observational study, seven cases of cancer with concomitant tuberculosis were included. All the patients were proven malignancy patients with advanced or metastatic stage. On clinical suspicion, a tissue diagnosis was obtained which led to change in staging as well as management of the patients.

RESULTS: Seven patients were having primary diagnosis of carcinoma breast, carcinoma esophagus, coepidermoid carcinoma of submandibular salivary gland, carcinoma tongue, squamous cell carcinoma skin, carcinoma cervix and carcinoma endometrium. They showed FDG uptake at distant sites leading to upstaging of disease. On histopathological examination, lymph nodal mass reported granulomatous lymphadenitis, leading to change of overall staging and management of the patients.

DISCUSSION AND CONCLUSIONS: Whole Body PET CT scan may produce false positive results and upstage the disease. It should be evaluated and interpreted with caution in cases of doubtful findings and any abnormal FDG accumulation in PET CT scan at unusual locations should be evaluated carefully and confirmed histopathologically.