Immature Teratoma with Embryonal Carcinoma; a Rare Malignant Mixed Germ Cell Tumour in a 14-Year-Old Boy: Case Report

Abstract

Introduction Mixed germ cell tumours (MGCTs) are rare and prone to affecting younger populations [1]. These tumours are characterised by aggressive clinical behaviour; most patients present with metastasis at initial diagnosis [2]. Case Presentation A 14-year-old male patient presented to the endocrinologist complaining of gynecomastia and a lump on the right testicle. Upon physical examination, the right testicle was found to be enlarged. Ultrasonography of the testicles revealed a heterogeneous structure similar to a benign epidermoid cyst, measuring approximately 2.3 x 1.7 cm with low echogenicity, containing calcifications, and without internal blood flow. A follow-up MRI revealed a multichambered, well-defined structure with fatty inclusions, showing no significant accumulation of contrast agent - similar to a benign epidermoid cyst, spermatocele, or other conditions. The 2,5 cm solid round tumour was removed. Histopathology analysis revealed a primary mixed germ cell tumour of the testis (immature teratoma and embryonal carcinoma), stage I pT1a, N0, M0. Right-sided orchiectomy was performed for radical tumour removal. Discussion MGCTs contain 2 or more germ cell elements. Combinations consisting of teratoma and embryonal carcinoma are more likely to occur. MGCTs with malignant transformation such as carcinomas are impending metastasize and have further aggressive potential [3]. Conclusions This case highlights the importance of considering germ cell tumour in the differential diagnosis of persistent testicular masses that mimic epidermoid cyst, spermatocele, or other cystic transformation, accentuate the importance of early recognition and precise histopathological assessment to prevent misdiagnosis and establish timely treatment.