B43-48 A Case of Mistaken Identity: Rheumatoid Nodules Mimicking Metastatic Disease

Abstract Introduction Rheumatoid arthritis (RA) can cause a spectrum of thoracic manifestations, including rheumatoid pulmonary nodules. When new nodules appear, they may be indistinguishable from malignancy on computed tomography (CT), creating a diagnostic dilemma. We report a case of subacute cough and dyspnea in a woman with RA and new bilateral nodules. Case Report A 63-year-old woman with seropositive RA on immunosuppression, prior breast cancer, 20 pack year smoking history, and asthma presents for one month of worsening dry cough and exertional dyspnea. CT chest for the unexplained dyspnea demonstrated multiple new and enlarged bilateral pulmonary nodules (largest 9 mm) without lymphadenopathy or effusion, raising concern for metastatic disease given her oncologic and smoking history. Mammogram was negative. Bronchoscopy with bronchoalveolar lavage (BAL) showed lymphocytic predominance; Gram stain and cultures were negative. Inflammatory markers were low. CT of the abdomen and pelvis showed no malignancy. After discharge, elevated Aspergillus galactomannan in the BAL was found. She was treated for probable invasive pulmonary aspergillosis with Voriconazole; however, follow-up CT demonstrated further worsening of nodular lesions. Following a comprehensive multidisciplinary discussion involving infectious disease, pulmonology, rheumatology and interventional pulmonology specialists, she underwent a robotic/navigational biopsy. The biopsy were negative for malignancy, or infectious etiology. Given the patient’s history of RA, rheumatoid nodules were considered the most probable diagnosis. The patient was subsequently initiated on Golimumab, and follow-up CT imaging demonstrated a reduction in size of the nodules. Discussion This case report emphasizes that not all new or enlarging pulmonary nodules are indicative of malignancy. In patients with RA or other inflammatory diseases, it is crucial to consider benign etiologies such as rheumatoid nodules, infection, or drug-induced granulomas. Confounding risk factors, including a history of malignancy and smoking, can influence toward a malignant diagnosis. In our case, patient’s history of seropositive RA and response to immunosuppressive therapy along with no response to antifungal therapy with biopsy negative for malignancy supported the most likely etiology to be RA related. The therapeutic response to golimumab was also unique in our case, as the nodules demonstrated radiologic regression rather than progression typically associated with TNF-α inhibitors. For patients presenting with RA and new multifocal pulmonary nodules, rheumatoid nodules should remain a high-priority consideration in the differential diagnosis, even when radiographic findings suggest metastases or an infectious etiology. Prompt multidisciplinary assessment and targeted tissue sampling are critical for preventing unwarranted oncologic evaluations and for guiding appropriate immunosuppressive management. This abstract is funded by: None