SHM Converge Scientific Abstract ePoster Gallery-Bark Worse Than Its Bite: Pet Scan Belies Benign Cause

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This case highlights how tuberculosis (TB) can mimic metastatic cancer on PET-CT imaging. A 61-year-old woman with rheumatoid arthritis treated with methotrexate and adalimumab, and a history of previously treated latent TB, presented with three months of cough and shortness of breath. CT imaging showed bilateral pleural effusions and hypodense splenic lesions. Pleural fluid was a lymphocytic exudate with elevated adenosine deaminase, and PET-CT demonstrated multiple FDG-avid foci in the spleen, omentum, peritoneum, and pleura, initially raising strong concern for disseminated malignancy.<br /><br />Despite three negative sputum AFB samples, pleuroscopy with pleural biopsy revealed granulomatous inflammation with punctate necrosis. Cultures from both pleural fluid and biopsy later grew Mycobacterium tuberculosis, confirming disseminated extrapulmonary TB. The patient was started on RIPE therapy and arranged for TB clinic follow-up.<br /><br />The report emphasizes that both TB and malignancy are key considerations in lymphocyte-predominant exudative pleural effusions. FDG PET scans are sensitive for detecting abnormal tissue activity, but they cannot reliably distinguish infection/inflammation from cancer because both can show similarly elevated SUV values. Therefore, tissue biopsy remains essential for definitive diagnosis.<br /><br />The case also underscores the increased risk of active or disseminated TB in patients receiving anti-TNF therapy, where extrapulmonary disease is common. Shared decision-making and careful TB risk assessment are important before initiating these immunosuppressive agents.

Asset Subtitle

Aparna Rathnam

Meta Tag

Author List Alberto Busmail Haylock, Aparna Rathnam, Harleen K. Sidhu, Mya Lwin, Thanushiree Sivalingam

Category Clinical Vignettes

Concept Tuberculosis

Concept Biopsy

Concept TNF-alpha Inhibitor Therapy

Concept Metastatic Cancer

Concept Culture

Distinguished Non-Finalist

Presenter Organization NYC Health + Hospitals / Elmhurst, Icahn School of Medicine at Mount Sinai.

Presenting Author Aparna Rathnam

Track Adult

Keywords

tuberculosis

PET-CT

metastatic cancer

extrapulmonary TB

pleural effusion

anti-TNF therapy

rheumatoid arthritis

granulomatous inflammation

Mycobacterium tuberculosis

FDG-avid lesions

Tuberculosis

Biopsy

TNF-alpha Inhibitor Therapy

Metastatic Cancer

Culture