A young female with seropositive rheumatoid arthritis complicated by cavitary rheumatoid nodules in the lung: Case report.

RATIONALE: Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by inflammatory arthritis and extra-articular involvement, with lung involvement being the most common extra-articular manifestation. Rheumatoid nodules are highly specific for RA, occurring in 20% of patients and are more common in male patients with a history of smoking. This article aims to explore the diagnostic approach, key points of differential diagnosis, and treatment strategies of this disease by reporting the diagnosis and treatment process of a case of RA complicated with rheumatoid nodules in the lungs with cavity formation, and by reviewing the literature, providing diagnostic ideas for clinicians in treating similar cases. PATIENT CONCERNS: The patient had a history of a persistent cough of unknown etiology, which persisted despite medical therapy. Additionally, the patient developed symmetric, progressive polyarticular pain, a key manifestation of the underlying disease. DIAGNOSES: This case was diagnosed as rheumatoid nodules in the lungs through a comprehensive analysis of the patient's clinical history (including RA and related symptoms), laboratory tests (elevated inflammatory markers and positive specific antibodies), chest CT imaging features (multiple nodules with cavities in both lungs), and pathological examination results (excluding tumors, tuberculosis and fungal infections, showing fibrinoid necrosis), and based on a multidisciplinary consultation. INTERVENTIONS: The patient received comprehensive treatment including hormones and antirheumatic drugs to relieve symptoms and control the progression of RA. OUTCOMES: One year after discharge, the patient's pulmonary lesions gradually subsided and there was no disease progression. LESSONS: For RA patients with positive serology, if multiple subpleural nodules or masses with cavities are found on chest CT, pulmonary rheumatoid nodules should be considered first. However, tuberculosis, fungal infection, tumor, and vasculitis must be systematically excluded. The pathology may be atypical, and the consistency of clinical, imaging and pathological findings and dynamic follow-up should be emphasized.