This case report describes a rare idiopathic chronic hematocele that mimicked testicular neoplasm in a 17-year-old male with a two-year history of right scrotal swelling and discomfort. Clinical examination suggested a testicular mass, while sonography indicated an encysted hydrocele with a differential diagnosis of scrotal hydatid cyst. Surgical exploration revealed a large hematocele with the testis incorporated into its wall. Histopathology confirmed chronic inflammation without malignancy. This case report highlights the importance of considering idiopathic chronic hematocele in the differential diagnosis of scrotal masses.