Giant paratesticular immunoglobulin G4-related disease mimicking malignancy: A case report

Immunoglobulin G4-related disease (IgG4-RD) is a rare fibroinflammatory disorder that can mimic malignancy. We report a 30-year-old man with Down syndrome presenting with a giant painless scrotal mass and pruritic erythematous skin lesions. Tumor markers were normal, while CT revealed a bilateral scrotal soft-tissue mass measuring 21 × 31 × 36 cm with calcifications and suspicious iliac lymph nodes, strongly suggesting advanced malignancy. Radical surgical excision with bilateral orchiectomy was performed. Histopathological, immunohistochemical established the diagnosis of IgG4-RD. Subsequent corticosteroid therapy achieved a favorable outcome. This case highlights an exceptionally rare scrotal manifestation of IgG4-RD and its diagnostic challenge.