IgG4 Related Disease of Epididymis, Mimicking Testicular Malignancy – A Rare Entity

Abstract

Immunoglobulin G4 related disease (IgG4-RD) is a systemic fibro inflammatory condition that usually presents with multiorgan involvement. We present a rare case of 54 year old male with an isolated IgG4-RD of epididymis. The patient presented with a progressive swelling of the left testicle. A clinical diagnosis of tuberculosis was made. Ultrasound scrotum showed a relatively hetero-echoic mass lesion involving the left epididymis in close proximity to the left testis. There was a focal spindle cell proliferation and an increase in number of plasma cells and keloid like collagen. Immunohistochemistry was positive for vimentin and IgG4 and negative for CD34. Serum level of IgG4 was elevated (165 mg per dL). Computed tomography of abdomen and thorax did not show any systemic involvement. HE was posted for excision of the epididymal mass. Intraoperatively, the mass was found to be densely adherent to left testicle and inseparable from it, necessitating left total orchiectomy. Histopathology and immunohistochemistry with elevated serum IgG4 levels confirmed the diagnosis of IgG4-RD of the epididymis. To the best of our knowledge, this condition is an extremely rare entity, with only very few cases of isolated IgG4-RD of epididymis reported in medical literature, with no other systemic manifestations.