Testis Tumors Overview

Testis Tumors

• The testis is the primary reproductive organ composed of tubules.
• The testis is covered by the tunica albuginea and peritoneum.
• During fetal development, the gonads move outside the peritoneum, which is the retroperitoneum.
• The tunica vaginalis, a mesothelial covering, includes a visceral layer on the testis and a parietal layer on the scrotum.
• The tunica albuginea staging does not change with tumor infiltration, but the tunica vaginalis staging does.
• The gonads are responsible for reproduction, having stromal and parenchymal components.
• Stromal component supports and produces hormones; Leydig cells are the primary type of stromal cell.
• Parenchymal component (seminiferous tubules) undergoes spermatogenesis, producing male gametes. Sertoli cells are involved.
• Germ cell tumors are the most common in puberty and young adulthood.

Testicular Tumor Prevalence

• Testicular tumors comprise about 1% of all male cancers.
• The majority of testicular tumors are germ cell tumors.
• The incidence rate of testicular tumors has increased, while the death rate has decreased.
• Testicular cancers commonly occur between puberty and young adulthood.
• Risk factors include prior testicular tumors, family history, cryptorchidism (undescended testes), and androgen insensitivity syndrome (AIS).
• A number of testicular tumors exhibit increased risk of death and/or metastasis.

Germ Cell Tumors

• Germ cell tumors are broadly categorized into seminomas and nonseminomas.
• Seminomas peak in adulthood, while nonseminomas peak in adolescence.
• Risk factors include prior testicular tumors, family history, cryptorchidism, and genetic conditions.

Germ Cell Tumor Classification

• Tumors are classified based on origin (GCNIS related vs. not) and microscopic morphology.
• Seminomas resemble somatic cells.
• Teratomas resemble embryonic stem cells.
• Embryonal carcinomas resemble embryonic stem cells.
• Yolk sac tumors resemble yolk sac cells.
• Choriocarcinomas resemble placental cells

Physiological Role

• OCT4 and c-KIT markers are important immunochemical markers distinguishing GCNIS and non-GCNIS related tumors.
• Primordial germ cells express OCT4 and c-KIT during normal maturation, but eventually, gene expression is suppressed.
• Inappropriate continued gene expression of OCT4 and c-KIT can lead to risk factor-triggered carcinogenic outcomes. Environmental stressors can also impact this process.

Other Important Types of Tumors

• Choriocarcinoma: produces high levels of human chorionic gonadotropin (hCG).
• Yolk sac tumors commonly produce high levels of alpha-fetoprotein (AFP).
• Seminomas may have elevated hCG levels.

Mixed Germ Cell Tumors

• Common combinations of non-seminomatous germ cell tumors include:
  • Embryonal carcinoma + teratoma
  • Embryonal carcinoma + seminoma
  • Embryonal Carcinoma + YST + teratoma
  • Other combinations.

Gross and Microscopic Appearance Key Characteristics

• Provide detailed descriptions of both gross and microscopic appearances and distinguishing characteristics for specific tumor types (seminomas, teratomas, embryonal carcinomas, etc.), such as cell morphology and tissue architecture.
• Include detailed descriptions of tumor characteristics in terms of size, shape, color, and consistency to assist in differential diagnosis.