Seminoma overview

# Overview
Seminoma is the most common testicular tumor and accounts for approximately 45% of all primary testicular tumors. However, seminoma can arise outside of the testicle, most often within the anterior mediastinum, e.g. anterior mediastinal germ cell tumor. Seminoma is the most common germ cell tumor of the testis. It is the male counterpart of the dysgerminoma, which arise in the ovary. It should not be confused with the unrelated tumor called spermatocytic seminoma. Based on the histology, testicular seminoma may be classified into three subtypes: classic, anaplastic, and spermatocytic. On gross pathology, seminoma is characterized by pale gray to yellow nodules that are uniform or slightly lobulated and often bulge from the cut surface. On microscopic pathology, seminoma is characterized by the cells with fried egg appearance with clear cytoplasm and central nucleus with prominent nucleolus, with interspersed lymphocytes and syncytiotrophoblasts. Approximately 24% of Stage I seminomas have lymphovascular invasion for stage I (Tx, N0, M0). Intertubular seminoma may not form a discrete mass and mimic a benign testis. Seminoma  is demonstrated by positivity to tumor markers, such as OCT4, CD117, D2-40, and CD117. There are no known direct causes for seminoma. To view a comprehensive list of risk factors that increase the risk of seminoma, click here. Testicular germ cell tumor accounts for around 1-2% of all malignancies in males up to the age of 65, but they are the most common nonhematologic malignancy in males 15-49 years old. Approximately 50% of germ cell tumours are seminomas. The mean age at diagnosis of testicular seminoma is between 15 and 35 years. This is about 5 to 10 years older than men with other germ cell tumors of the testis. Testicular seminoma usually affects individuals of the Caucasian race. African american individuals are less likely to develop testicular seminoma. Seminoma grows slower than non-seminomatous germ cell tumors. Common complications of seminoma include recurrence, lymph node metastasis, distant metastasis, and secondary malignancies. Prognosis of seminoma is good for all stages with greater than 90% cure rate. The International Germ Cell Cancer Consensus Group divides seminoma into two prognosis groups: good and intermediate. Symptoms of seminoma include painless testicular mass with discomfort, back pain, abdominal discomfort, or abdominal mass. Laboratory findings consistent with the diagnosis of seminoma include abnormal serum tumor marker levels (LDH, HCG). Abdominal and pelvic CT scans may be diagnostic of seminoma. CT scan may detect metastases of seminoma to the para-aortic, inguinal, or iliac lymph nodes. Visceral metastasis may also be seen. Pelvic MRI may be diagnostic of testicular seminoma. On MRI, seminoma is characterized by multinodular tumors of uniform signal intensity. Findings on MRI suggestive of seminoma include hypo- to isointense on T2-weighted images and inhomogenous enhancement on contrast enhanced T1-weighted images. Other diagnostic studies for seminoma include biopsy, FDG-PET scan, and bone scan. Radical inguinal orchiectomy is the first treatment for any stage of testicular seminoma and it is usually done as part of diagnosis. Adjunctive radiotherapy and chemotherapy may be given.

# Classification
Based on the histology, testicular seminoma may be classified into three subtypes: classic, anaplastic, and spermatocytic.

# Pathophysiology
On gross pathology, seminoma is characterized by pale gray to yellow nodules that are uniform or slightly lobulated and often bulge from the cut surface. On microscopic pathology, seminoma is characterized by the cells with fried egg appearance with clear cytoplasm and central nucleus with prominent nucleolus, with interspersed lymphocytes and syncytiotrophoblasts. Approximately 24% of Stage I seminomas have lymphovascular invasion for stage I (Tx, N0, M0). Intertubular seminoma may not form a discrete mass and mimic a benign testis. Seminoma  is demonstrated by positivity to tumor markers, such as OCT4, CD117, D2-40, and CD117.

# Causes
There are no known direct causes for seminoma. To view a comprehensive list of risk factors that increase the risk of seminoma, click here.

# Differentiating Primary Central Nervous System Lymphoma from other Diseases
Seminoma must be differentiated from other diseases that cause testicular mass, such as non seminomatous germ cell tumor, sex cord tumors, focal orchitis, focal intratesticular hemorrhage, testicular torsion, tuberculosis, and polyorchidism.

# Epidemiology and Demographics
Testicular germ cell tumor accounts for around 1-2% of all malignancies in males up to the age of 65, but they are the most common nonhematologic malignancy in males 15-49 years old. Approximately 50% of germ cell tumours are seminomas. The mean age at diagnosis of testicular seminoma is between 15 and 35 years. This is about 5 to 10 years older than men with other germ cell tumors of the testis. Testicular seminoma usually affects individuals of the Caucasian race. African american individuals are less likely to develop testicular seminoma.

# Risk Factors
Common risk factors for testicular seminoma include undescended testis, caucasian race, previous tumor in the contralateral testis, and family history of testicular germ cell tumor.

# Screening
There is insufficient evidence to recommend routine screening for seminoma.

# Natural History, Complications and Prognosis
Seminoma grows slower than non-seminomatous germ cell tumors. Common complications of seminoma include recurrence, lymph node metastasis, distant metastasis, and secondary malignancies. Prognosis of seminoma is good for all stages with greater than 90% cure rate. The International Germ Cell Cancer Consensus Group divides seminoma into two prognosis groups: good and intermediate.

# Diagnosis

## Staging
Seminoma grows slower than non-seminomatous germ cell tumors. Common complications of seminoma include recurrence, lymph node metastasis, distant metastasis, and secondary malignancies. Prognosis of seminoma is good for all stages with greater than 90% cure rate. The International Germ Cell Cancer Consensus Group divides seminoma into two prognosis groups: good and intermediate.

## Symptoms
Symptoms of seminoma include painless testicular mass with discomfort, back pain, abdominal discomfort, or abdominal mass.

## Physical Examination
Common physical examination findings of seminoma include unilateral, nontender mass with or without retroperitoneal or inguinal lymphadenopathy.

## Laboratory Findings
Common laboratory tests performed in seminoma include complete blood count and blood chemistry tests. Laboratory findings consistent with the diagnosis of seminoma include abnormal serum tumor marker levels (LDH, HCG).

## CT
Abdominal and pelvic CT scans may be diagnostic of seminoma. CT scan may detect metastases of seminoma to the para-aortic, inguinal, or iliac lymph nodes. Visceral metastasis may also be seen.

## MRI
Pelvic MRI may be diagnostic of testicular seminoma. On MRI, seminoma is characterized by multinodular tumors of uniform signal intensity. Findings on MRI suggestive of seminoma include hypo- to isointense on T2-weighted images and inhomogenous enhancement on contrast enhanced T1-weighted images.

## Other Imaging Findings
There are no other imaging findings associated with seminoma.

## Other Diagnostic Studies
Other diagnostic studies for seminoma include biopsy, FDG-PET scan, and bone scan.

# Treatment

## Medical Therapy
The optimal therapy for seminoma depends on the stage at diagnosis.

## Surgery
Radical inguinal orchiectomy is the first treatment for any stage of testicular seminoma and it is usually done as part of diagnosis.

## Primary Prevention
There are no primary preventive measures available for seminoma.

## Secondary Prevention
Secondary prevention strategies following seminoma include regular follow-ups for every 26 months for the first 3 years and every 612 months after 3 years. Tests are often part of follow-up care include blood tests to check serum tumor marker levels, chest x-rays, and CT scans of the abdomen and pelvis.