A uterine pseudotumor of immunoglobulin G4-related disease.

Immunoglobulin G4-related disease (IgG4-RD) is characterized by systemic lesions presenting as swellings, nodules and wall thickenings. The first-line therapy is glucocorticoids. This disease is common among middle-aged and elderly men, and its uterine mass formation is uncommon. We encountered a 39-year-old nulliparous woman with an IgG4-related uterine mass and enlarged pelvic lymph nodes. Complete remission was achieved by fertility-sparing resection of the uterine mass without glucocorticoids. This case showed that IgG4-RD can present as a uterine mass and we need to be careful of its diagnostic and therapeutic strategies because an IgG4-related uterine mass is difficult to distinguish from sarcoma or malignant lymphoma. Our case also demonstrated that IgG4-related lymphadenopathy could regress spontaneously without complete lymphadenectomy or glucocorticoids when IgG4-RD does not affect vital organs. A pelvic mass with hyperproteinemia may be a hint to remind us of IgG4-RD and may trigger a preoperative immunoglobulin test.