IgG4-Related Disease with Selective Testicular Involvement- A Rare Entity: Case Report with Review of Literature.

Immunoglobin-G4 related disease (IgG4-RD) is an auto-immune inflammatory condition where patients present with a tumour-like mass that shows infiltration by plasma cell and subsequent fibrosis. It is a systemic condition that primarily involves the salivary glands, pancreas, kidneys, aorta, and retroperitoneum amongst other organs. Testicular involvement is a rare occurrence in this disease entity. A 55-year old male patient presented with the complaints of pain and swelling in the right scrotal region. Right-sided orchidectomy was carried out which on histopathology showed features suggestive of IgG4-RD which was later confirmed on immunohistochemistry. Whole body MRI revealed that no other organ was involved in the disease process in this patient. IgG4-RD has a variable clinical course and considerable overlap with its differentials. Imaging studies and serum IgG4 levels are neither confirmatory nor customarily diagnostic in every case. The only confirmatory diagnostic investigation is histopathological examination, which shows infiltration of IgG4+ plasma cells and fibrosis in the involved tissue. Whenever a mass-forming lesion with typical histomorphological features is encountered with involvement of multiple organs/anatomic sites, IgG4-related disease should be considered among the differentials, and clinicians of all disciplines should be familiar with this disease entity.