A 22-year-old unmarried woman from Delhi presents with a 3-month history of progressive abdominal distension and mild left-sided abdominal pain. On examination, she is afebrile, with a palpable left lower abdominal mass. Serum β-hCG is 45,000 mIU/mL (normal <5), and serum α-fetoprotein (AFP) is 8,500 ng/mL (normal <10). Pelvic ultrasound shows a 12 cm heterogeneous left ovarian mass with solid and cystic components. What is the most likely diagnosis?

Explanation

## Diagnosis: Mixed Germ Cell Tumor ### Clinical Presentation The combination of **elevated β-hCG and elevated AFP** in a young woman with a large heterogeneous ovarian mass is pathognomonic for a **mixed germ cell tumor**, most commonly containing both **yolk sac tumor (endodermal sinus tumor)** and **choriocarcinoma** components. ### Tumor Markers in Germ Cell Tumors | Marker | Yolk Sac Tumor | Choriocarcinoma | Dysgerminoma | Embryonal Carcinoma | | --- | --- | --- | --- | --- | | **AFP** | ↑↑↑ (most sensitive) | Normal | Normal | ↑ | | **β-hCG** | Normal/mild ↑ | ↑↑↑ (very high) | Normal | ↑ | | **LDH** | ↑ | ↑ | ↑ | ↑ | **Key Point:** The **simultaneous elevation of both AFP and β-hCG** indicates a **mixed germ cell tumor** with at least two different histologic components. Pure yolk sac tumor typically shows only AFP elevation; pure choriocarcinoma shows only β-hCG elevation. ### Pathologic Features - **Yolk sac tumor (endodermal sinus tumor):** Schiller-Duval bodies (papillary structures with central blood vessel), microcystic pattern, hyaline globules - **Choriocarcinoma:** Syncytiotrophoblastic and cytotrophoblastic cells, high mitotic activity, hemorrhage and necrosis - **Mixed tumors:** Heterogeneous appearance on imaging (solid + cystic), rapid growth, often large at presentation ### Clinical Pearl **Mixed germ cell tumors are the most common malignant ovarian germ cell tumors in adolescents and young women.** They present with abdominal mass, pain, and markedly elevated tumor markers. The presence of **both AFP and β-hCG elevation** is the diagnostic hallmark. ### High-Yield Facts - **Age:** Peak incidence 15–25 years (adolescents and young adults) - **Unilateral:** >95% of cases (unlike dysgerminoma which can be bilateral in 10–15%) - **Prognosis:** With modern chemotherapy (BEP: bleomycin, etoposide, cisplatin), 5-year survival >90% even for advanced disease - **Tumor markers are prognostic:** Higher levels correlate with tumor burden and chemotherapy response ### Management Algorithm ```mermaid flowchart TD A[Young woman with ovarian mass]:::outcome --> B{Tumor markers elevated?}:::decision B -->|AFP + β-hCG both ↑| C[Mixed germ cell tumor]:::outcome B -->|Only AFP ↑| D[Yolk sac tumor]:::outcome B -->|Only β-hCG ↑| E[Choriocarcinoma]:::outcome B -->|All normal| F[Dysgerminoma or mature teratoma]:::outcome C --> G[Staging: CT chest/abdomen/pelvis]:::action G --> H[Chemotherapy: BEP regimen]:::action H --> I[Monitor tumor markers]:::action ``` [cite:Robbins 10e Ch 22]