F-18 FDG PET/CT findings of intrathoracic lymphadenopathy in EBUS-TBNA-proven anthracosis

Anthracosis is a kind of pneumoconiosis that may cause parenchymal and bronchiolar injury and mediastinal lymphadenopathy. In this study, we aimed to investigate F-18 fluorodeoxyglucose (FDG) positron emission tomography/computerized tomography (PET/CT) findings of patients who had anthracosis diagnosis with endobronchial ultrasonography (EBUS).

The patients who underwent EBUS-transbronchial needle aspiration (TBNA) and were diagnosed with anthracosis in a five year period were included in the study. The diagnosis was confirmed by surgery/ radiological stability. Demographic characteristics such as age, sex, smoking status, and occupational and environmental exposures were recorded. The characteristics: diameter (short axis), shape, central hilar structure, necrosis sign, echogenicity, and margins measured by EBUS, and maximum standardized uptake value (SUV max value) by PET/CT of the lymph node stations were evaluated.

One hundred thirty-three patients with 239 lymph node stations were investigated. Biomass exposure was detected in nearly half of the patients (n= 55, 41.4%) and occupational exposure was detected in 32 (24.1%) patients. Eighty-six (64.7%) patients had more than 20 packs/years of smoking history. Most of the lymph nodes (80.8%) have a higher PET/CT SUV max value than 2.5. The mean diameter of the lymph nodes measured by thorax CT (16.2 ± 6.5 mm) and EBUS (12.7 ± 5.6 mm) did not show any difference according to PET/CT SUV max value of ≥2.5 or not (p> 0.05). Subcarinal lymph nodes were significantly larger than the other lymph node stations. The lymph nodes with necrosis sign (p= 0.028), absence of central hilar structure (p= 0.013), and heterogeneous echogenicity (p= 0.008) were statistically significantly related to higher SUV max value.

Anthracosis should be considered as a cause of false-positive PET/CT results for mediastinal lymph nodes, especially in patients with a history of occupational and environmental exposure including biomass and smoking.