Thoracolithiasis: a rare and frequently underrecognized entity - a retrospective single-center study and narrative...

Thoracolithiasis is a rare benign pleural condition classically described as a freely mobile, calcified intrapleural loose body. Systematic data on non-mobile thoracolithiasis and its clinical context are scarce. This study aimed to characterize the clinical, radiologic, etiologic, and geographic features of non-mobile thoracolithiasis, to explore isolated versus secondary forms, and to identify scenarios in which these lesions mimic malignant pleural nodules.

This retrospective, observational study included adult patients diagnosed with thoracolithiasis at a tertiary thoracic surgery center between January 2010 and December 2024. Eligible cases had radiologic and/or surgical confirmation and complete clinical and imaging data. Demographic, clinical, radiologic, and surgical variables, including asbestos exposure and coexisting thoracic disease, were collected. Patients were stratified by sex, symptom status, calcification, and isolated versus secondary thoracolithiasis. Statistical comparisons used the Mann-Whitney U test and Chi-square or Fisher's exact test (two-tailed p < 0.05). A narrative review of the literature was conducted to contextualize the findings of the present cohort.

Twenty patients with pathologically confirmed thoracolithiasis (mean age 64.0 ± 10.5 years; 70% male; 75% with a smoking history) were included. No lesion showed evidence of mobility on available imaging review or intraoperative assessment. 60% of lesions were non-calcified, with a mean maximum diameter of 29.4 ± 17.8 mm. Thoracolithiasis coexisted with lung cancer in 40% and with other thoracic disease in 30%; 30% were isolated. Patients with calcified lesions were older than those with non-calcified lesions (70.0 vs. 60.0 years, p = 0.023). Lung cancer occurred exclusively in older male smokers and was significantly associated with male sex (p = 0.010) and smoking history (p = 0.027). Isolated thoracolithiasis was more frequent in female non-smokers, and all isolated cases underwent diagnostic exploration (100% vs. 35.7%, p = 0.025). Asbestos-exposed patients (25%) originated exclusively from inland provinces, whereas most non-exposed patients resided in a coastal, non-asbestos-endemic region.

Non-mobile thoracolithiasis exhibits two clinically distinct patterns: a secondary type in older male smokers with thoracic malignancy, and an isolated type in non-smoking women without additional thoracic disease. Non-mobile, often non-calcified thoracoliths in low-risk patients frequently mimic malignant pleural nodules and may lead to avoidable thoracoscopic or open exploration. Recognizing this broader spectrum of thoracolithiasis may help refine diagnostic algorithms and reduce unnecessary invasive procedures.