Extensive Tuberculous Lymphadenitis Mimicking Distant Lymph Node Metastasis on F-18FDG PET/CT in a Patient with a History of Malignant Melanoma
A 62-year-old woman was diagnosed with malignant melanoma on the left sole of the foot and underwent wide excision of the sole melanoma with inguinal lymphadenectomy. She was well without evidence of tumor recurrence 4 years after surgery.\nAfter 4 years, she complained of a palpable right neck mass. F-18FDG PET/CT was performed for the recurrent melanoma evaluation. A F-18FDG PET/CT showed markedly increased FDG uptakes (SUV max: 12.4) in the bilateral neck, mediastinum, hila, left parasternal, and abdominal lymph nodes, which were suspicious for metastases ().\nPlain chest X-ray and PET/CT of both lungs showed normal.\nUltrasonography (US) showed multiple enlarged cervical lymph nodes considered to be suspicious for metastasis (), and US guided fine needle aspiration was performed for diagnosing the cause of cervical lymphadenopathy.\nCytology result was negative for malignancy, and immunocytochemistry result for HMB45 that reacts against an antigen present in melanomas was also negative. Therefore, excisional lymph node biopsy was performed to discover the reason behind the image-pathologic discordance.\nExcisional lymph node biopsy for cervical lymph node showed chronic granulomatous lymphadenitis with caseous necrosis () and tuberculosis polymerase chain reaction was positive, compatible with tuberculosis lymphadenitis. Finally, tuberculosis lymphadenitis was diagnosed by excisional biopsy.