Primary Extra-Gonadal Retroperitoneal Seminoma, Clinically Mimicking Sarcoma

Area of Science:

• Oncology
• Pathology
• Radiology

Background:

• Extra-gonadal Germ cell tumours (EGCTs) originate outside the gonads, predominantly affecting young males.
• Common locations include the mediastinum, retroperitoneum, pineal gland, and sacrococcygeal region.
• While often non-seminomatous, seminomatous EGCTs occur, posing diagnostic challenges.

Observation:

• A case report of a 25-year-old male with a significant abdominal mass and normal testes is presented.
• Imaging (ultrasound, CECT) revealed large retroperitoneal masses.
• Fine Needle Aspiration Cytology (FNAC) indicated a germ cell tumour.

Findings:

• Histopathological examination confirmed the retroperitoneal masses as seminoma.
• Periodic Acid Schiff (PAS) staining and Immunohistochemistry for Placental Alkaline Phosphatase (PLAP) validated the diagnosis.
• The retroperitoneum is a frequent site for sarcomas, necessitating careful differential diagnosis.

Implications:

• Extra-gonadal Germ cell tumours, specifically seminoma, should be considered in the differential diagnosis of abdominal soft-tissue masses.
• Accurate diagnosis requires a combination of imaging, cytology, and histopathology.
• This case underscores the importance of considering EGCTs in young males presenting with unexplained abdominal masses.