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Testicular Tumor

Though representing only about 1% of all human neoplasms; testicular tumor is the most common cancer in males of reproductive age group. Evidence suggests an approximate incidence of about 23% of 15–35-year-old males. Iincidence increases with age for unknown reasons.

Testicular tumors have been variously classified based on histology and prognostic outcome. The World Health Organization (WHO) has standardized the pathologic segregation of testicular malignancies.

The WHO taxonomy for testicular tumors is as follows:

Tumor type Subsets (if applicable)
Germ cell tumor
Precursor lesions Intratubular malignant germ cell tumor (carcinoma in situ)
Pure-form tumors (of single histology) Seminoma (variant: seminoma with syncytiotrophoblastic cells)

Spermatocystic seminoma (variant: spermatocystic with sarcoma)

Embryonal carcinoma

Yolk sac tumor

Polyembryoma

Trophoblastic tumors Choriocarcinoma
Teratoma Immature teratoma

Mature teratoma

Dermoid cyst

Teratoma with malignant areas

Mixed tumors
Sex-cord/gonadal stromal tumors
Pure forms Sertoli’s cell tumor:

  • Lipid-rich cell
  • Large cell calcifying
Incompletely differentiated sex cord/gonadal stromal tumors
Tumors of the thecoma/fibroma group
Mixed forms
Miscellaneous tumors
Unclassified forms Ovarian epithelial tumors

Carcinoid tumors

 Granulosa cell tumor Adult type of granulosa cell tumor

Juvenile type of granulose cell tumor

Tumors containing both germ cell and sex cord/gonadal stromal elements Gonadoblastoma

Mixed germ cell-sex cord/gonadal stromal tumors

Unclassified

Lymphoid and hematopoietic tumors Lymphoma

Plasmacytoma

Leukemia

Tumors of collecting duct and rete testis Adenoma

Carcinoma

Tumors of tunica, epididymis, spermatic cord, supporting structures, and appendices Adenomatoid tumor

Mesothelioma

Adenoma

Carcinoma

Melanotic neuroectodermal tumor

Soft tissue tumors

Unclassified tumors

Secondary tumors

Testicular tumors are either germ cell tumors (GCTs) or non-germ cell tumors (NGCTs). A succinct description of each is as follows:

Germ Cell Tumors

Introduction

Germ cell tumors are the most common of all testicular tumors. They account for about 95% of all testicular malignancies and are classified into seminomatous and non-seminomatous types, with about 60% being of mixed type. The literature suggests that the only known risk factor for GCTs is Klinefelter syndrome (47,XXY), which is associated with mediastinal nonseminomatous germ cell tumors. This is commonly characterized by their location on the midline plane of the human body and thus may appear anywhere from the pineal gland to the coccyx.

Epidemiology

Germ cell tumors are the most prevalent solid tumors of 20–34-year-old men and the 2nd most common in men aged 35–40 years. These tumors are more common in the caucasian population.

There is approximately a 2%–3% incidence of bilateral tumors.

Frequency

A study in Norway put the incidence of GCTs at about 0.5 per 1,000,000 men per year. This is approxiately 2% of the number of testicular cancers reported.

The incidence of various histologic types of GCTs is as follows:

Type Incidence
Seminoma 30%–60%
Embryonal carcinoma 40% (mixed form); 2%–4% pure form
Teratoma 5%–10%
Mixed GCT 60%
Pure choriocarcinoma 1%

Classification

There are 5 basic types of GCTs:

  1. Seminoma: This type of tumor generally occurs in men between the ages of 25 and 55.
  2. Teratoma
  3. Choriocarcinoma
  4. Embryonal cell carcinoma
  5. Yolk sac tumor

Note: Seminoma may resemble a yolk sac tumor by forming tubular and microcystic growth patterns.

Pathogenesis

GCTs arise from totipotent germ cells which undergo further differentiation into extraembryonic and intraembryonic cell types. The origin of the basic types of GCTs can be summarized as follows:

Tumor Origin
Seminoma

Teratoma

Totipotent germ cell
Yolk sac tumors
Choriocarcinoma Extraembryonic differentiation of totipotent germ cells
Yolk sac tumor
Teratoma Intraembryonic differentiation

Various conditions predispose an individual to developing a GCT. These conditions can be summarized as follows:

Predisposing condition Evidence
Testicular atrophy While the exact role is not yet defined, it is believed that nonspecific or mumps-associated atrophy is likely caused by testicular cancer.
Trauma An incidental finding
Cryptorchidism About 6%–10% of testicular malignancy patients have undescended testes. There is a markedly increased risk (13 times) of developing cancer in patients with a maldescended testis. Almost one-quarter of patients with bilateral cryptorchidism and history of testicular tumor develop a second GCT.
Hormonal The ale children of mothers exposed to diethylstilbestrol and oral contraceptives are prone to develop testicular cancer.

Presentation

The most frequent presentation of testicular malignancy is painless unilateral scrotal swelling. Other infrequent symptoms include:

  • Infertility
  • Dull, aching pain
  • Difficulty in walking
  • Heaviness in the scrotum, lower abdomen, and perianal region
  • Acute pain

About 10% of patients present symptoms of metastasis with chronic long-standing and often ignored scrotal swelling. Despite the name, germ cell tumors occur both within and outside the testis. Symptoms include the following:

Symptom Interpretation
Painless neck swelling Supraclavicular lymph node metastasis
Abdominal discomfort Retroduodenal metastasis
Lumbar back pain Psoas muscle involvement
Back pain, bony pains Skeletal metastasis
Lower extremity edema Venous obstruction

Diagnosis

Clinical examinations offer few salient features traditionally used to differentiate benign scrotal masses from testicular tumors. Bimanual palpation is key. Clinical findings can be summarized as follows:

Test Explanation
Transillumination Negative
Fluctuation Negative
Palpation of the testes Firm, hard, or fixed mass can occasionally be felt
Getting above the swelling Possible

Ultrasonography should always be performed. The hypoechoic region within the tunica albuginea is of critical importance. Other advanced radioimaging tests are of ancillary nature. Their findings can be summarized as follows:

Diagnostic Test Explanation
Abdominal CT It is most effective in identifying retroperitoneal lymph node involvement. Clear visualization of kidney, ureters, retro-crural space and the para-aortic region is feasible.
MR Imaging Testicular tumors enhance early on MRI and are T2 hypointense.
PET scan It is used to detect radiographic aberrations after chemotherapy. It fails to identify microscopic nodal metastatis.
Chest Skiagram Used to screen the chest in patients with negative abdominal CT findings.
Chest CT Performed in patients with abnormal abdominal CT findings.

Treatment

The treatment of GCT is heavily dependent on the stage of the disease. The first step towards staging is to perform orchiectomy to determine the histologic features. Histology and radiology with tumor markers assessment whenever relevant; help in ascertaining the correct stage of the disease and developing the most definite management protocol. Most patients with germ cell cancer will need to be treated with combination chemotherapy for at least 3 cycles. The chemotherapy regimen most commonly used in germ cell tumors is called PEB (or BEP), and consists of bleomycin, etoposide, a platinum-based antineoplastic (cisplatin)

The AJCC staging for GCTs is universally followed. Based on four parameters: T for primary tumor, N for lymph node status, M for metastasis and S for serum markers status; there are 4 stages defined from stage I for locally contained disease to a progressively increasingly complex grading where stage IV implies distant metastatic illness. AJCC staging details are as follows:

Parameter Subset
Primary tumor (T) pTx: primary tumor cannot be assessed

pT0: no evidence of primary tumor

pTis: intratubular germ cell neoplasia

pT1: tumor limited to the testis and epididymis and no vascular or lymphatic invasion

pT2: Tumor limited to the testis and epididymis with vascular or lymphatic invasion or tumor extending through the tunica albuginea with involvement of tunica vaginalis.

pT3: invasion of the spermatic cord with or without vascular/lymphatic invasion

pT4: invasion of the scrotum

Regional lymph nodes (N) Nx: cannot be assessed

No: no regional lymph node metastasis

N1: lymph node mass 2 cm or less in greatest dimension

N2: lymph node mass more than 2, less than 5 cm

N3: lymph node mass more than 5 cm

Distant metastasis (M) M0: no evidence of distant metastasis

M1: non-regional nodal or pulmonary metastasis

M2: nonpulmonary visceral metastasis

Serum tumor markers (S): AFP LDH HCG
S0: ≤ N ≤ N ≤ N
S1: < 1,000 < 1.5 times N < 5,000
S2: 1,000–10,000 1.5–10 times N 5,000–50,000
S3: > 10,000 > 10 times N > 50,000

Seminomas tend to spread lymphatically to the para-aortic lymph nodes (versus penile drainage through the inguinal LNs) and nonseminomatous metastasize hematogenously, for example: to the lungs.

Once staged, patient is treated using the following modalities:

  • Surgical resection with retroperitoneal lymph node dissection (RPLND)
  • Chemotherapy: cisplatin-based chemotherapy
  • Radiation: abdominal and pelvic
  • Surveillance

The individual tumor types of GCTs can be summarized as follows:

Tumor Characteristics Serum marker Prognosis
Seminoma Seminoma constitutes 35–70% of GCTs. Only 5–10% of tumors are anaplastic with lethal potential; the rest have a very good outcome. Typical morphological appearance resembles ‘Fried-egg’ Placental ALP (PLAP) is present in about 90% of seminomas.

About 10% patients stain positive for HCG. HCG is from syncytiotrophoblastic cells and does not behave as choriocarcinoma.

Late metastasis, lymphatics, radiosensitive.

 

Excellent outcome with good response to radiation and carboplatin-based chemotherapy.

The female ovarian tumor ‘dysgerminoma’ is its counterpart.

Embryonal Contributing to about 3–6% of GCTs; embryonal carcinoma is seen in males of age 25–35 years. Embryonal carcinomas stain positive for CD30, keratin and infrequently to PLAP. HCG positivity is attributed to syncytiotrophoblasts adjacent to EC cells. Prognosis is not as favorable as seminoma.
Yolk sac (EST) Most prevalent testicular malignancy in pre-pubertal males, especially boys < 3 yrs of age. Schuller-Duval bodies are characteristically seen. ALP positive in about 90% of these tumors. Aggressive
Choriocarcinoma Represent about 1-2% of all GCTs.

Trophoblastic cells are appreciated on histology.

HCG positivity in more than 90% of patients; some also stain for PLAP. Aggressive associated with hemorrhagic tendency and hyperthyroidism.
Teratoma Teratomas comprise of 2 or more embryonic germ cell layers. They are incriminated in almost 1/3rd  of childhood GCTs. Childhood teratomas are benign; while adult teratomas are malignant. Immature form is aggressive Prognosis is heterogenous depending on the cell lines involved; less favorable compared to embryonal.

Other NGCTs are relatively very rare and their clinical characteristics can be summarized as follows:

Non-germ cell tumors(NGCTs) Clinical presentation
Leydig cell tumor Golden brown color, contains Reinke crystals (eosinophilic cytoplasmic inclusions) produces androgens or estrogens: leads to gynaecomastia in males, precocious puberty in boys.
Sertoli cell tumor Androblastoma from sex cord stroma
Testicular lymphoma Most common testicular cancer in older men; not a primary cancer; arises from metastatic lymphoma to testes.

Summary

Testicular tumors can be segregated into eerm cell tumors and non-germ cell tumors based on cell of origin.

Germ cell tumors are divided into seminomatous and non-seminomatous types, whereby seminomatous have very good prognosis and are chemo-radiosensitive.

It is of crucial importance to differentiate between testicular neoplasm and benign scrotal masses.

History, clinical examination and ultrasonography findings often corroborate to form a preliminary diagnosis of testicular neoplasm. Further management depends exclusively on the stage of malignancy; determination of which begins with orchiectomy.

Adjuvant treatment options include radiation, chemotherapy, surgical resection with RPLND and surveillance.

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