Q. A 30-year-old man presents with a painless testicular mass. An ultrasound shows a well-circumscribed, homogeneous, non-hemorrhagic tumor. Histology is shown. What is the likely diagnosis?

Explanation

## Correct Answer: D. Seminoma Seminoma is the most common germ cell tumor of the testis in India, accounting for ~40% of all testicular GCTs. The clinical and radiological presentation here—painless testicular mass, well-circumscribed, homogeneous, non-hemorrhagic appearance on ultrasound—is classic for seminoma. Histologically, seminomas are characterized by sheets of uniform, large, pale-staining cells (resembling primordial germ cells) with clear cytoplasm, prominent nucleoli, and a fibrous stroma with lymphocytic infiltration. The homogeneity and lack of hemorrhage/necrosis distinguish it from non-seminomatous GCTs, which are typically heterogeneous due to multiple tissue types and areas of necrosis. Seminomas are radiosensitive and chemosensitive, with excellent prognosis when detected early. The age of presentation (30 years) fits the typical peak incidence of 35–40 years. Elevated β-hCG may occur in ~10% of cases, but AFP is characteristically normal—a key discriminator from non-seminomatous tumors. ## Why the other options are wrong **A. Choriocarcinoma** — Choriocarcinoma is a non-seminomatous GCT that produces very high β-hCG levels and typically presents with hemorrhage, necrosis, and heterogeneous appearance on imaging. It is rare as a pure tumor (usually mixed GCT) and causes rapid systemic metastases. The homogeneous, non-hemorrhagic ultrasound appearance rules this out. NBE trap: confusing any GCT with high β-hCG production. **B. Teratoma** — Teratomas are non-seminomatous GCTs containing tissues from multiple germ layers (bone, cartilage, fat, hair). They appear heterogeneous on ultrasound with cystic and solid components, often with calcification. The well-circumscribed, homogeneous appearance described here is incompatible with teratoma's mixed histology. Teratomas also have poor prognosis and are chemoresistant. **C. Yolk sac tumor** — Yolk sac tumor (endodermal sinus tumor) is a non-seminomatous GCT that produces AFP, not β-hCG. It typically presents with heterogeneous appearance, hemorrhage, and necrosis. Histologically, it shows characteristic Schiller-Duval bodies and microcystic patterns, not the uniform sheets of pale cells seen in seminoma. It has worse prognosis than seminoma. ## High-Yield Facts - **Seminoma** is the most common testicular GCT (~40% of all GCTs), with peak incidence at 35–40 years. - **Homogeneous, non-hemorrhagic ultrasound appearance** is pathognomonic for seminoma; non-seminomatous GCTs are heterogeneous with necrosis. - **AFP is normal in pure seminoma**; β-hCG may be mildly elevated (~10% of cases); both are normal in ~80% of seminomas. - **Histology: uniform sheets of pale cells** with clear cytoplasm, prominent nucleoli, fibrous stroma with lymphocytic infiltration. - **Radiosensitive and chemosensitive**; excellent prognosis (>95% 5-year survival in early stages) with adjuvant therapy. - **Stage I seminoma** (confined to testis) is managed by radical inguinal orchiectomy ± adjuvant radiotherapy or chemotherapy per Indian guidelines. ## Mnemonics **SEMINOMA vs Non-Seminomatous GCT (NSGCT)** **SEMI** = **S**ingle histology, **E**xcellent prognosis, **M**ild markers, **I**maging homogeneous. **NSGCT** = **N**ultiple tissues, **S**evere markers, **G**rim prognosis, **C**haotic imaging (heterogeneous, hemorrhage, necrosis). **Marker Memory: Seminoma vs NSGCT** **Seminoma**: AFP normal, β-hCG mild/normal. **Yolk sac**: AFP high. **Choriocarcinoma**: β-hCG very high. **Teratoma**: mixed markers or normal. Use: When you see normal AFP + mild β-hCG in a homogeneous testicular mass → think seminoma. ## NBE Trap NBE pairs "non-hemorrhagic, homogeneous appearance" with non-seminomatous GCTs to trap students who memorize that NSGCTs are "more aggressive." In reality, the imaging homogeneity is a red flag for seminoma; NSGCTs are always heterogeneous due to mixed tissue types and necrosis. ## Clinical Pearl In Indian clinical practice, any young man presenting with a painless testicular mass and homogeneous ultrasound appearance should be presumed to have seminoma until proven otherwise. Early radical inguinal orchiectomy followed by staging (CT chest/abdomen, tumor markers) determines adjuvant therapy—making prognosis excellent if caught early. This contrasts sharply with non-seminomatous GCTs, which require aggressive multimodal therapy. _Reference: Robbins Ch. 21 (Testis); Harrison Ch. 101 (Testicular Cancer)_