IgG4-Related Tumefactive Lesions at the Pulmonary Artery Causing Stenosis of Bilateral Primary Branches and Resultant Pulmonary Hypertension.

IgG4-related disease (IgG4-RD) is a newly recognized but rare entity involving multiple organs, with autoimmune pancreatitis, retroperitoneal mass, and the inflammation of glands being typical in most cases. IgG4-related perivascular lesions, although uncommon, have been increasingly reported in recent years. Diagnosis of IgG4-RD relies on comprehensive consideration of characteristic histopathological and immunostaining results, clinical and imaging findings, and serological results according to several widely recognized diagnostic criteria. This benign disorder frequently presenting tumefactive lesions should be distinguished from malignancy and other inflammatory mimics. Here we report a case of tumefactive mass at the bifurcation of the pulmonary trunk causing stenosis of the proximal left and right pulmonary artery (PA) and resultant pulmonary hypertension (PH). Bypass from the PA trunk to the right branch distal to stenosis was performed to resolve the obstructive hemodynamic disturbance and PH. Glucocorticoid monotherapy was performed after a diagnosis of definite IgG4-RD. Longitudinal disease activity assessment via imaging modalities, serological parameters, and IgG4-RD responder index verified no relapse during follow-up and the validity of the treatment strategy.