A Rare Case of IgG4-related Disease Manifesting as an Ulcerated Gastric Cancer Complicated With Gastric Mucormycosis

Background: IgG4-related disease (IgG4-RD) is a novel clinical entity that mimics many malignant, infectious, and inflammatory disorders. Many organs or tissues are now known to be involved in IgG4-RD; however, there has been no report about IgG4-RD of stomach with fungal infection. Case presentationWe reported a 56-year-old male with IgG4-RD manifesting as ulcerated gastric cancer complicated with gastric mucormycosis. Both clinical and imaging manifestations were atypical, in clinical, it was highly suspected that the disease is a malignant tumor as ulcerated gastric cancer. However, no pathological evidence of malignancy could be found in repeated biopsies and surgically excised gastric specimen. Histological examination showed ulcer and inflammatory granulation with lymphocytes and plasma cells in sheets, inflammation of vascular wall, formation of new fibrous tissue and inflammatory necrosis with hyphae and spores. The plasma cells had immunohistochemically strong staining for CD38, CD138, kappa, lambda, IgG and IgG4. And notably, IgG4/IgG positive plasma cell ratio was more than 40%, kappa/lambda positive staining ratio was approximately 1:1. Gastric mucormycosis was diagnosed with hyphae and spores confirmed by Gomori's methenamine silver staining and immunofluorescence and confocal laser-scanning microscopy. IgG4-RD manifesting as ulcerated gastric cancer complicated with gastric mucormycosis was diagnosed by multidisciplinary team discussion from gastroenterology, radiology and pathology department. The patient vomited blood three times for the following month. An emergent exploratory laparotomy was conducted, and a mass with 10×9×8cm adhered closely to adjacent organs could be touched in lesser curvature of gastric antrum. Anastomotic leakage occurred after the surgery, symptomatic treatments (negative pressure drainage and antibiotics) were applied without steroids and anti-fungus drugs. The patient gradually recovered and was advised to consult gastroenterology department for further steroids and anti-fungus drugs treatment. ConclusionsTo our knowledge, it is the first report about IgG4-related disease manifesting a gastric ulcer with mucormycosis infection.