Testicular cancer pathophysiology

Classification
Although testicular cancer can be derived from any cell type found in the testicles, more than 95% of testicular cancers are germ cell tumors. Most of the remaining 5% derive from Leydig cells or Sertoli cells. Thus, the focus of diagnosis is on determining which germ cell tumor is present. Correct diagnosis is necessary to ensure the most effective and least harmful treatment. To some extent, this can be done via blood tests for tumor markers, but differential diagnosis requires examination of the histology of a specimen by a pathologist.

Histology
After removal, a testicular tumor is classified by a pathologist according to its histology.

Germ cell tumors of the testis, by frequency

 * 40% mixed (usually teratoma plus another)
 * 35% seminoma (germinoma of the testis)
 * 20% embryonal carcinoma
 * 5% teratoma (pure)
 * <1% choriocarcinoma
 * Gonadoblastoma

Also: Intratubular germ cell neoplasms (the in-situ stage of germ cell tumors)

Non-germ cell tumors of the testis

 * Sertoli-Leydig cell tumor (usually benign)
 * Gonadoblastomas

Secondary tumors of the testis

 * Lymphoma
 * Leukemic infiltration of the testis
 * Metastatic tumors