STEPTRACKERREPRODUCTIVE + ONCOLOGY | PATHOLOGY + PHARMACOLOGY | HIGH-YIELD REVIEW

Testicular Germ Cell Tumors

The most common solid cancer of young men — seminoma versus the nonseminomas, the markers that tell them apart, and why most are cured.

FOCUS ON
Painless, firm testicular mass in a man 15–35 that doesn't transilluminate; risk: cryptorchidism, Klinefelter; i(12p). Seminoma: fried-egg cells, PLAP, LDH, no AFP, radiosensitive, best prognosis. Nonseminomas: embryonal, yolk sac (AFP), choriocarcinoma (hCG), teratoma (malignant in adults). Inguinal orchiectomy — never scrotal biopsy. Cisplatin-based chemo cures most.
TUMOR · TOPIC
MECHANISM · ORIGIN
FEATURES
MARKER · CLUE
General features
~95% of testicular tumors; arise from germ cell neoplasia in situ (GCNIS); isochromosome 12p
Painless firm mass; dull ache; may present with back pain (retroperitoneal nodes) or gynecomastia
Cryptorchidism, Klinefelter, family history
Seminoma
most common
Undifferentiated germ cells
Homogeneous, lobulated tan mass; large cells with clear cytoplasm ("fried egg"), fibrous septa with lymphocytes; peak ~35
↑ PLAP, LDH; hCG may be mildly ↑; AFP never ↑ · radiosensitive
Spermatocytic tumor
Not from GCNIS
Men > 65; mixture of cell sizes
Rarely metastasizes
Embryonal carcinoma
Totipotent primitive cells
Painful, hemorrhagic, necrotic mass; glandular/papillary sheets; 20–30s
hCG ± AFP (often mixed) · aggressive
Yolk sac tumor
Extraembryonic yolk sac differentiation
Most common testicular tumor in boys < 3; Schiller-Duval bodies
↑↑ AFP
Choriocarcinoma
Cyto- and syncytiotrophoblast
Small primary, early hematogenous spread (lungs, brain); hemorrhage
↑↑ hCG → gynecomastia, hyperthyroidism
Teratoma
Somatic tissues from germ layers
Adults: malignant potential even if mature (unlike ovary) · children: benign
Markers usually normal · chemo-resistant
Mixed germ cell tumor
Most nonseminomas contain several components
Behaves like its most aggressive element
Any ↑ AFP = nonseminomatous component
Spread
Lymphatic along testicular vessels
Para-aortic (retroperitoneal) nodes first — not inguinal; choriocarcinoma by blood
Scrotal skin → inguinal nodes (why no scrotal incision)
Treatment
Inguinal orchiectomy → staging → radiation (seminoma), RPLND, chemotherapy
BEP: bleomycin, etoposide, cisplatin
Bleomycin → lung fibrosis · cisplatin → nephro-, oto-, neurotoxicity

Mechanism — germ cell lineages

GCNISIntratubular
→
SeminomaStays primitive
Embryonal carcinomaTotipotent
Embryonal
→
TeratomaEmbryonic tissue
Yolk sacAFP
ChoriocarcinomahCG

Same family as the ovarian germ cell tumors (seminoma = dysgerminoma) — but adult testicular teratomas are malignant.

Markers by tumor

TUMOR
AFP
hCG
OTHER
Seminoma
—
± (mild)
PLAP, LDH, c-KIT
Embryonal
±
±
CD30
Yolk sac
↑↑
—
Schiller-Duval
Choriocarcinoma
—
↑↑
Bleeds early
Teratoma
—
—
Mature/immature tissue

How it's tested

COMMON CONFUSIONSeminoma can raise hCG slightly from scattered syncytiotrophoblasts, but it never raises AFP. A "seminoma" with high AFP has a nonseminomatous component.
THE TRAPA firm testicular mass is never biopsied through the scrotum — it is removed through an inguinal incision to avoid seeding scrotal lymphatics.
YOUR APPROACHAge (boy, young man, older man) → painful/hemorrhagic or not → markers (AFP, hCG, LDH) → histology → spread (para-aortic vs blood) → cisplatin toxicity.

If you see… think…

25-year-old with a painless firm testicular mass → germ cell tumor — inguinal orchiectomy
Testicular tumor with fried-egg cells, lymphocytes, ↑ PLAP → seminoma
Chromosome abnormality in testicular GCT → isochromosome 12p
2-year-old boy with testicular mass and ↑ AFP → yolk sac tumor
Small testicular primary, lung metastases, very high hCG, gynecomastia → choriocarcinoma
Painful hemorrhagic testicular mass in a 28-year-old → embryonal carcinoma
Mature teratoma in an adult testis → still malignant potential
First lymph nodes involved → para-aortic (retroperitoneal)
Pulmonary fibrosis after testicular cancer chemo → bleomycin
Hearing loss and rising creatinine after BEP → cisplatin