[IgG4-related diseases of retroperitoneum in urinary and male reproductive system: a clinicopathological analysis of eleven cases].

To analyze the clinicopathological features of IgG4-related diseases (RD) of retroperitoneum and the urinary and male reproductive system (IgG4-RUMR). A total of 11 IgG4-RUMR cases from January 2013 to March 2021 were retrospectively collected at Peking University Third Hospital and Shandong Provincial Hospital affiliated to Shandong First Medical University. The clinicopathologic features, laboratory and imaging findings were analyzed and scored according to the 2019 ACR/EULAR classification criteria for IgG4-RD. The 11 patients (male:female is 9∶2; mean age 59 years, range from 44 to 83 years) were initially admitted to the Deparment of Urology/Kidney Transplantation (10 cases) and the Department of Oncology (1 case). All patients had urogenital disorders or imaging abnormalities. Three of the 11 patients had a history of IgG4-RD such as lacrimal gland engorgement, salivary gland engorgement and IgG4-associated pancreatitis. Abnormal retroperitoneal soft tissue and hydronephrosis were found in eight cases, while epididymal and spermatic cord masses were found in one case, simple renal mass in one case, and"benign prostatic hyperplasia"in one case. In the 10 patients tested for serum IgG4, the serum IgG4 level was 0.8-14.4 g/L. Histologically, all cases showed significant lymphoplasmacytic infiltration and storiform fibrosis, and some were accompanied by obliterative phlebitis. The number of IgG4 positive plasma cells was 12-155 per high-power field, and the IgG4/IgG ratio was 15%-77%. According to the 2019 ACR/EULAR IgG4-RD classification standard 11 cases scored 20-48 points, all of which met the diagnostic criteria of IgG4-RUMR. Therapeutically, the patient with a simple renal mass underwent partial nephrectomy. The patient with prostate lesion underwent transurethral resection of prostate and was initially diagnosed as nonspecific chronic prostatitis. Later, the patient was admitted again because of salivary gland swelling, and the pathologic diagnosis was amended. The patient with epididymal and spermatic cord masses participated in a clinical trial about retroperitoneal fibrosis. The remaining eight patients received symptomatic treatment such as adhesiolysis and stent placement. All the patients were subsequently treated with glucocorticoid/immunosuppressant and symptoms relieved. IgG4-RUMR is uncommon. In clinical practice, information from clinical, serologic, radiologic and pathologic evaluations must be integrated. IgG4-RUMR should be considered in the differential diagnosis of urinary and male reproductive diseases. The 2019 ACR/EULAR classification criteria for IgG4-RD, while relatively complex, are objective and practical in the diagnosis of IgG4-RUMR.