A33-42 Getting to the Heart of the Issue

Abstract Introduction Pulmonary artery masses have a broad differential. CT may offer initial characterization, but cardiac MRI and PET/CT provide more definitive information. Histopathologic evaluation is often required. We present a rare case of a pulmonary artery mass with an elevated IgG4 index, initially misclassified as more common benign and malignant entities. Case-Presentation: A 61-year-old never smoking female was referred to the pulmonary clinic for abnormal imaging. Her history was only for patent ductus arteriosus repair in infancy. She initially presented with pleuritic chest pain and was found to have near occlusive mass in the distal main pulmonary artery extending into the proximal left main pulmonary artery. This was presumed to be pulmonary embolism, and anticoagulation was started. At presentation, she reported mild dyspnea and improving chest pain, without constitutional symptoms. Cardiac MRI revealed restricted diffusion and enhancement consistent with pulmonary artery sarcoma. PET-CT revealed FDG avid pulmonary artery mass (SUV max 14.5) without other hypermetabolic lesions. She subsequently underwent resection of the main and proximal left PA mass resection with bovine pericardial reconstruction. Histopathology showed a dense lymphoplasmacytic infiltrate with prominent plasma cell infiltration, IgG4/IgG ratio of 40%, and 10 IgG4 positive plasma cells per high power field. No histiocytic proliferation or evidence of other atypia. Her serum IgG4 level, CRP, ANCA serology, and fungal serology were normal. Discussion Here we present the case of isolated pulmonary artery mass with elevated IgG4 index of greater than 40% without other organ manifestations of IgG4 related disease (IgG4-RD). Cases of IgG4-RD related infiltration with a pulmonary artery mass have been reported, yet these typically present with other systemic manifestations, vascular inflammation, luminal stenosis, and/or pulmonary hypertension. Based on ACR 2019 IgG4 related disease classification criteria, these patients would not strictly meet criteria for IgG4 related disease. After extensive multidisciplinary discussion, we have elected to hold systemic treatment for IgG4-RD. She will be followed closely, monitoring new evidence of organ infiltration that would warrant systemic treatment. Conclusion Pulmonary artery masses should raise suspicion for various benign etiologies, such as chronic thromboembolism, and malignant entities, including pulmonary artery sarcoma. Cardiac MRI, PET/CT, and histopathology were critical in this patient’s evaluation. IgG4-related disease can rarely present as an intimal pulmonary artery mass. However, this is typically accompanied by systemic findings suggestive of IgG4-RD, other vascular infiltration, and/or pulmonary hypertension, all of which were absent in this patient. This abstract is funded by: None