Inflammatory Pseudotumor of the Stomach with Infiltration of IgG4-positive Plasma Cells and Tissue Fibrosis: Gastric Manifestation of IgG4-related Disease?

Abstract

Introduction: IgG4-related disease is an increasingly recognized syndrome of unknown etiology with lymphoplasmacytic infiltrate enriched in IgG4-positive plasma cells and variable degrees of fibrosis. Recently, much attention has been focused on this syndrome, components of which are now increasingly recognized in almost every organ system. However, IgG4-related inflammatory pseudotumor (IPT) of the stomach has seldom been described in the literature. Case report: A 44-year-old man was admitted to our hospital with a three-day history of epigastralgia and tarry stool, anemia, and syncope. His past medical history included anti-phospholipid antibody syndrome, cerebral infarction, and diabetes mellitus. He was diagnosed as having upper gastrointestinal hemorrhage and endoscopy was performed. On endoscopy, a submucosal tumor was recognized in the greater curvature of the gastric lower body, which had hemorrhagic ulceration. Computed tomography scan showed an extraluminally growing mass lesion approximately 4 cm in size. On suspicion of hemorrhagic gastrointestinal stromal tumor, laparoscopic partial gastrectomy was performed. Histopathological examination demonstrated a lesion located in between the submucosa and subserosa with infiltration of IgG4-positive plasma cells and tissue fibrosis. The number of IgG4-positive plasma cells per HPF was 127, and the ratio of IgG4-positive/IgG-positive cells was 52%. These findings were most consistent with a diagnosis of IgG4-related IPT of the stomach. His postoperative course was uneventful, and he was discharged immediately. Discussion: IPT is a rare non-neoplastic lesion that is characterized by inflammatory cell infiltration and variable fibrotic reactions. The etiology is still unclear but is thought to be infectious or autoimmune in nature. A relationship between some populations of ITP and IgG4 has been suggested in recent years. There is currently no consensus on the number of IgG4-positive plasma cells required for the diagnosis of IgG4-related IPT. However, according to the literature, IgG4-positive cells > 60-100/HPF and a ratio of IgG4-positive/IgG-positive cells > 40%-50% are thought to be highly suggestive of IgG4-related disease. Generally, IgG4-related disease has a benign clinical course and usually responds to corticosteroids. Our patient underwent laparoscopic surgery because of uncontrollable hemorrhage. Considering that IgG4-related IPT may respond to conservative treatment with corticosteroids, we should be aware of this rare condition.