Seminoma

Seminoma
Classification and external resources
ICD-10	C62.
ICD-9	186
ICD-O:	M9061/3
OMIM	273300
DiseasesDB	12966
eMedicine	med/2250
MeSH	D018239

Seminoma (also known as pure seminoma or classical seminoma) is a germ cell tumor of the testis. It is one type of testicular cancer^[1] that is believed to originate from the germinal epithelium of the seminiferous tubules. Seminomas are one of the more common types of testicular tumor, and account for approximately half of all germ cell tumors of the testis. ^[2]

Presentation

The average age of diagnosis is 40 years. This is about 5 to 10 years older than men with other germ cell tumors of the testes. In most cases they produce masses that are readily felt on testicular self-examination, however in up to 11 percent of cases, there may be no mass able to be felt, or there may be testicular atrophy. Testicular pain is reported in up to one fifth of cases. Low back pain may occur after metastasis to the retroperitoneum ^[2].

Some cases of seminoma can present as a primary tumour outside the testis, in which case it is called a germinoma. ^[2]

Diagnosis

Blood tests may detect the presence of placental alkaline phosphatase (PLAP) in fifty percent of cases. Human chorionic gonadotropin (hCG) may be elevated in some cases, but this correlates more to the presence of trophoblast cells within the tumour than to the stage of the tumour. Serum alpha fetoprotein is not elevated in classical seminoma. ^[2]

The cut surface of the tumour is fleshy and lobulated, and varies in colour from cream to tan to pink. The tumour tends to bulge from the cut surface, and small areas of haemorrhage may be seen. These areas of haemorrhage usually correspond to trophoblastic cell clusters within the tumour. ^[2]

Microscopic examination shows that seminomas are usually composed of either a sheet-like or lobular pattern of cells with a fibrous stromal network. The fibrous septae almost always contain focal lymphocyte inclusions, and granulomas are sometimes seen. The tumour cells themselves typically have abundant clear to pale pink cytoplasm containing abundant glycogen, which is demonstrable with a periodic acid-Schiff (PAS) stain. The nuclei are prominent and usually contain one or two large nucleoli, and have prominent nuclear membranes. Foci of syncytiotrophoblastic cells may be present in varied amounts. The adjacent testicular tissue commonly shows intratubular germ cell neoplasia, and may also show variable spermatoctyic maturation arrest. ^[2]

POU2AF1 and PROM1 have been proposed as possible markers.^[3]

Treatment

In recent years, these tumors have been shown to have dramatic sensitivity to both radiotherapy^[4] and cytotoxic chemotherapy. The management of childhood seminoma is similar to that of adult seminoma. Inguinal orchiectomy is required in almost all cases.^{[citation needed]}

5-year survival rate is approximately 90% as of 2008.^{[citation needed]}

A study of 31 men with metastatic germ cell tumor of the testis and delayed orchidectomy found that in men with pure seminoma, chemotherapy alone was sufficient to eliminate the cancer from the testis. The authors of this study suggest that treatment of pure seminoma may not require orchidectomy. Event-free survival of this group of men at an average followup of 4 years was 81.8%.^[5]

Relation to spermatocytic seminoma

Spermatocytic seminomas are not considered a subtype of seminoma and unlike other germ cell tumours do not arise from intratubular germ cell neoplasia.^[6]

Additional images

Histopathological image of metastatic seminoma in the inguinal lymph node. Hematoxylin & eosin stain.

Histopathological image of metastatic seminoma in the inguinal lymph node. At higher magnification. Hematoxylin & eosin stain.

Micrograph (high magnification) of a seminoma. H&E stain.

References