Tuberculosis Mimicking Tumor Progression on Dual-tracer 68Ga-DOTATATE and 18F-FDG PET/CT in Metastatic Neuroendocrine Tumor of Unknown Primary: A Potential Imaging Pitfall in Neuroendocrine Tumor Surveillance.

Abstract

False-positive findings on molecular imaging can pose significant diagnostic dilemmas in oncological cases. We report an elderly woman with metastatic neuroendocrine tumor of unknown primary who underwent 5 cycles of [177Lu]Lu-DOTATATE PRRT and achieved a partial response. On follow-up, [68Ga]Ga-DOTATATE and [18F]FDG-PET/CT scans demonstrated a new-onset FDG avid-hypermetabolic, low-grade SSTR-expressing cervical lymph node chain extending into the mediastinum, raising concern for disease progression or a second malignancy. Histopathology of the lymph nodes revealed granulomatous inflammation consistent with tuberculosis. This case highlights tuberculosis as a potential cause of false-positive dual-tracer PET positivity and the need for histologic confirmation before changing the management.