Mature Testicular Teratoma Mimicking Hydrocele in a 3-Year-Old Boy: Case Report and Literature Review.

Testicular tumors are rare in children, accounting for only 1% to 2% of pediatric solid tumors. Mature teratomas (MTs) are a benign subtype that typically occur in prepubertal boys and may occasionally mimic hydroceles. We report a case of a 3-year-old boy with left testicular swelling initially suspected to be a hydrocele. Over several months, the swelling evolved into a firm, painless mass. Ultrasound and MRI revealed a multiloculated cystic lesion with internal vascularity replacing most of the testicular parenchyma. Serum tumor markers, including alpha-fetoprotein, β-human chorionic gonadotropin, and lactate dehydrogenase, were within normal limits. The patient underwent left inguinal orchiectomy, and histopathology confirmed a MT without immature or malignant elements. Postoperative recovery was uneventful. He underwent routine follow-up every 3 months for 2 years, including physical examinations, scrotal ultrasounds, and serum tumor marker assessments. Findings from the first and second follow-ups were normal, with no evidence of recurrence to date. This case underscores the importance of early imaging and tumor marker evaluation in children presenting with persistent scrotal swelling. A systematic diagnostic approach facilitates accurate diagnosis, and orchiectomy remains the standard treatment for prepubertal MTs.