Pulmonary Hyalinizing Granuloma With Associated Elevation in Serum and Tissue IgG4 Occurring in a Patient With a History of Sarcoidosis

Pulmonary hyalinizing granulomas (PHGs) are unusual fibrosclerotic inflammatory lung lesions. The organ-based manifestations of the recently defined IgG4-related sclerosing disease typically show dense fibrosis and heavy lymphoplasmacytic infiltrates. IgG4-related sclerosing disease is also defined by increased serum IgG4 levels and increased tissue levels of IgG4-positive plasma cells. The morphologic features of PHG overlap with those seen in...