Pathology of Testicular Tumors

Intratubular Germ Cell Neoplasia

The *in situ lesion of a germ cell tumor*, basically atypia of the germ cells and causes predisposition to neoplasia

Yolk Sac Tumors

Also termed *Endodermal Sinus Tumor*; most common germ cell tumor in *children* -Show *Schiller-Duval Bodies* -Make significant *AFP*

Testicular Teratomas

Contain all 3 germ layers; *mostly found in kids/infants*; classified into: 1. Mature Teratomas 2. Immature Teratomas 3. Malignant Teratomas

Genetics of Germ Cell Tumors

Defect on the *short arm of chromosome 12* is present in some 90% of testicular germ cell tumors

Equivalent of Mature Teratomas in Females are _____

Dermoid cysts

Leydig Cell Tumors

Golden brown color; contains *Reinke crystals* (eosinophilic cytoplasmic inclusions). Produce androgens (testosterone) or estrogens -> gynecomastia in men, precocious puberty in boys

Mixed Germ Cell Tumors

Half of the germ cell tumors exhibit more than one type of neoplastic germ cells; most frequent patterns are: 1. Teratoma with Embryonal (Teratocarcinoma) 2. Teratoma, Embryonal and Seminomas 3. Embryonal and Seminoma

Choriocarcinoma

Highly malignant testicular tumor, which represents germ cell extraembryonic differentiation to the components of the placenta (cyto and syncytiotrophoblast) -Cut surface contains marked hemorrhage and necrosis -Secretes *bHCG*

Immature and Malignant Teratomas

Malignant subtype teratomas; demonstrates the same arrangement as a mature teratoma, but the tissues are less differentiated, and more primitive -> more cancerous -> *age of PT* determines severity (older=bad)

Embryonal Carcinoma of Testis

Malignant tumor of the primitive glandular cells; second most common germ cell tumor, much more deadly than seminoma; tunica albuginea and epididymis are invaded -Tumor markers (bHCG, AFP) may be positive due to *mixing with other neoplasia* -Usually has metastasized before detection

Histogenesis of Germ Cell Tumors

One cell type involved: seminoma (most common); Many cell types: if somatic -> teratoma; if extraembryonic -> yolk sac or choriocarcinoma

Seminomas

One cell type involved; *boselated* upon cutting entire testis is replaced by tumor in over half the cases, which appears yellow-white -Exquisitely *sensitive to radiation*

Germ Cell Tumors

Originate from the neoplastic transformation of germ cells and reflect their capacity to differentiate along many histogenetic lines -Risk factors: FH, gonadal dysgenesis, prior dx of germ cell tumor in contralateral testis, cryptorchidism, Klienfelter's

Mature Teratoma

*Benign* teratoma subtype; solid and multicystic lesion that enlarges the testis. The cut surface exhibits mucinous cysts, with solid cartilaginous and osseous foci