Basic classification
All testicular neoplasms are divided into two major groups:
- Germ cell tumors. Originate from germ cells. They make up the vast majority (95%) of all testicular neoplasms. They are characterized by a malignant course, a tendency to rapid dissemination, and extensive metastasis. They may have a single histologic type or a mixed structure.
- Non-germ cell tumors. Develop from sex cord-stromal elements (Sertoli cells, Leydig cells). As a rule, they have a benign course, less often possessing malignant potential. Some of them are capable of producing steroid hormones, leading to specific symptoms (e.g., gynecomastia).
Germ cell tumors of a single histologic type
This group includes several independent nosologies with characteristic morphology:
- Classic seminoma. A malignant tumor of monomorphic germ cells. Macroscopically, it is a well-circumscribed, lobulated, yellowish-pink node. Microscopically, the cells form alveolar nests, and tumor growth is accompanied by lymphoid and granulomatous reactions. hCG is frequently elevated.
- Spermatocytic seminoma. A rare variant seen in older adults. Consists of three cell types (lymphocyte-like, intermediate, large). Characterized by slow, asymptomatic growth and extremely rare metastasis.
- Embryonal carcinoma. An aggressive tumor of young men (associated with HLA B13+). Macroscopically, it is a soft node with areas of necrosis and hemorrhage. The cells are pleomorphic with large nucleoli, forming solid and papillary structures. In one-third of cases, it expresses $\alpha$-fetoprotein (AFP).
- Yolk sac tumor. Most commonly affects children under 3 years of age. The main marker is a sharp rise in AFP in 100% of cases. Reticular honeycomb structures and Schiller-Duval bodies are identified in microsections. The prognosis in children is usually favorable.
- Choriocarcinoma. An extremely aggressive neoplasm with trophoblastic differentiation (cytotrophoblast and syncytiotrophoblast). It produces early and extensive hematogenous metastases, whereas the primary node may undergo fibrosis and scarring.
- Teratoma. A tumor with differentiation into somatic-type tissues. It can be mature (containing analogs of normal tissues, e.g., dermoid cyst) and immature (containing embryonic tissues, e.g., fetal glands or neuroepithelium).
Sex cord-stromal tumors
Account for about 5% of neoplasms. They include tumors derived from supporting and interstitial cells:
- Leydig cell tumor (leydigoma). Consists of polygonal cells, in whose cytoplasm lipids, lipofuscin, and Reinke crystals are often identified. In 10% of cases, it possesses malignant potential.
- Sertoli cell tumor (sertolioma). A rare yellowish node. Microscopically, it may have a tubular structure, a sclerosing, or a large-cell calcifying form.
- Granulosa cell tumors. Subdivided into the adult type (often accompanied by gynecomastia) and the juvenile type (the most common tumor in the first 6 months of life, associated with cryptorchidism).
Briefly: answers to topical questions
What serum tumor markers are determined in testicular germ cell tumors?
In testicular germ cell tumors, three main specific tumor markers are determined in blood serum. These include:
- Alpha-fetoprotein (AFP) — tested in blood serum.
- Human chorionic gonadotropin (hCG) — free beta-subunit is determined in blood.
- Lactate dehydrogenase (LDH) — enzyme activity is assessed in blood.
The presence of an elevated AFP level and a high hCG level (greater than 1000 mIU/mL) indicates the development of a malignant non-seminomatous germ cell tumor.
What criteria are used for TNM staging of testicular tumors?
For TNM staging of testicular tumors, criteria for assessing the primary tumor, the status of regional lymph nodes, and the presence of distant metastases are used.
- Primary tumor (T) — assesses the spread from a process confined within the testicular body to invasion of the spermatic cord or scrotal wall.
- Regional lymph nodes (N) — accounts for the presence of metastases ranging from solitary inguinal lymph node involvement to distant lymphogenous metastases.
- Distant metastases (M) — records the presence of distant hematogenous metastases.
Class and exam questions
What is the difference between mature and immature teratoma?
Mature teratoma consists of differentiated tissues (epithelium, cartilage, glands) and is generally benign. Immature teratoma contains embryonic elements (neuroepithelium, fetal glands) and is characterized by invasive growth and metastasis.
Which testicular tumor is specific to early childhood?
In children under 3 years of age, yolk sac tumor is most commonly found (marker: AFP). Juvenile granululosa cell tumor is also characteristic up to 6 months of age.
How does choriocarcinoma manifest clinically?
Its onset is often associated with symptoms of metastases: hemoptysis, back pain, or gastrointestinal bleeding. A high level of hCG and sometimes gynecomastia are also characteristic.
What else to study on this topic
- Mixed germ cell tumors: variants of histologic combinations
- Gonadoblastoma and its association with gonadal dysgenesis
- TNM classification of testicular tumors
- Pathogenesis and morphology of hydrocele
- Secondary malignant transformation of teratomas in adults
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