Spermatocytic seminoma

Background

In spite of the name of this testicular tumor, it has a very different clinical course and prognosis than the classic seminoma. The name was proposed based on the resemblance of the chromatin in intermediate and small cells to that of the primary spermatocytes and spermatogonia respectively. The exact spermatogenic cell type, from which this tumor develops, remains unknown. It comprises about 5% of testicular seminomas arising in men with the . It has not been reported in prepubertal children or adolescents. Unlike most testicular tumors, there is no ovarian homologue and does not arise in cryptorchid testis, extra-testicular sites, or in association with other germ cell tumors. Most cases are asymptomatic and may grow to a very large size. Less than 10% of cases are bilateral with synchronous or metachronous involvement. The tumor has a multinodular cut surface with a grey-fleshy tan surface. Occasionally, the tumor is multifocal within the testis.

INCIDENCE 5% of testicular tumors

AGE RANGE-MEDIAN Rare under 30 years
Mean age at diagnosis of 53.6 years (range 25 to 87 years)

SEX (M:F)
M, no female counterpart

LABORATORY/RADIOLOGIC/
OTHER TESTS
CHARACTERIZATION

Laboratory Markers No known serum markers

GROSS APPEARANCE/
CLINICAL VARIANTS CHARACTERIZATION

General
Bilateral tumors in 9%, usually asynchronous

Well circumscribed multilobulated or multinodular
Soft, friable, and gray tan with mucoid surface
May show cystic change with hemorrhage or necrosis

HISTOLOGICAL TYPES CHARACTERIZATION

General
Diffuse sheets of cells with edema filled cystic spaces.
There is little fibrous septa and lymphocytes, typical of classical seminomas.
There is considerable cellular pleomorphism with cells ranging from lymphocyte-like cells to intermediate cells to giant cells.
There is a high mitotic rate.

Polymorphous cell population with three types of neoplastic cells

VARIANTS

Anaplastic variant Anaplastic variant has, in addition to the same three cell types, cells with large vesicular nuclei and macronucleoli, multinucleated tumor giant cells, a high mitotic index, abnormal mitotic figures, blood vessel invasion, invasion of tunica albuginea, and necrosis. Many of these features cause diagnostic confusion with embryonal carcinoma with solid growth pattern. A lack of diffuse immunoreactivity for PLAP and epithelial markers would support the diagnosis of anaplastic spermatocytic seminoma. These anaplastic changes probably represent dedifferentiation but do not seem to alter the biological behavior of the neoplasm.

Sarcomatous change Sarcomatous change may rarely occur. The seminomatous and sarcomatous areas are intimately admixed, with no apparent morphologic transition between the two components. The sarcomatous elements have consisted of undifferentiated spindle cells or show rhabdomyosarcomatous differentiation. It is thought that it represents anaplastic transformation or dedifferentiation of a spermatocytic seminoma. The spermatocytic seminoma component has shown the usual histological features, except for an unusually high mitotic rate and frequent atypical mitotic figures in some cases. No other germ cell or teratomatous elements have been identified in any case. If present, this sarcomatous change leads to an aggressive course with extremely poor prognosis. Adjuvant chemotherapy seems to have no effect in the cases in which it has been tried. Fifty percent of patients die of metastases to lungs, liver, or retroperitoneum within in a few months.

SPECIAL STAINS/IMMUNOPEROXIDASE/
OTHER CHARACTERIZATION

Immunoperoxidase These tumors are typically negative for PLAP and HCG, unlike classic seminomas.

DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES

CHARACTERIZATION SPERMATOCYTIC SEMINOMA TYPICAL SEMINOMA

Proportion of germ cell tumors 1-2% 40-50%

Sites Testis only Testis, ovary, mediastinum, pineal, retroperitoneum

Bilaterality 9% 2%

Association with other forms of germ cell tumor No Yes

Association with IGCNU No Yes

Intercellular edema Common Uncommon

Composition 3 cell types, with denser cytoplasm, round nuclei 1 cell type, often clear cytoplasm, less regular nuclei

Stroma Scanty Prominent

Lymphoid reaction Rare to absent Prominent

Granulomas Extremely rare Often prominent

Sarcomatous transformation Occasional Absent

Glycogen Absent to scant Abundant

PLAP staining Absent to scant Prominent

hCG staining Absent Present in 10%

Metastases Extremely rare Common

ADDITIONAL DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES

Lymphoma

PROGNOSIS AND TREATMENT CHARACTERIZATION

Prognostic Factors

Survival Excellent prognosis

Metastasis There are only four reported cases of spermatocytic seminoma with metastases and the documentation in some of these cases is questionable leading to the current viewpoint that these tumors are best regarded as potentially capable of metastases.

Treatment Radical orchiectomy usually resulting in cure
Post-operative prophylactic radiation or chemotherpay do not offer any additional benefit and are not routinely recommended.

Cancer 1988; 61:409-14.
Hum Pathol 1996; 27:650-55.
Tumors of the Testis, Adnexa, Spermatic cord, and scrotum in Atlas of Tumor Pathology. Third Series. Fascicle 25. 1999.

Commonly Used Terms

Seminoma
Testis

Internet Links

Microscopic Photo

Last Updated 4/1/2001

INCIDENCE	5% of testicular tumors
AGE RANGE-MEDIAN	Rare under 30 years Mean age at diagnosis of 53.6 years (range 25 to 87 years)
SEX (M:F)	M, no female counterpart

LABORATORY/RADIOLOGIC/ OTHER TESTS	CHARACTERIZATION
Laboratory Markers	No known serum markers

HISTOLOGICAL TYPES	CHARACTERIZATION
General	Diffuse sheets of cells with edema filled cystic spaces. There is little fibrous septa and lymphocytes, typical of classical seminomas. There is considerable cellular pleomorphism with cells ranging from lymphocyte-like cells to intermediate cells to giant cells. There is a high mitotic rate. Polymorphous cell population with three types of neoplastic cells
VARIANTS
Anaplastic variant	Anaplastic variant has, in addition to the same three cell types, cells with large vesicular nuclei and macronucleoli, multinucleated tumor giant cells, a high mitotic index, abnormal mitotic figures, blood vessel invasion, invasion of tunica albuginea, and necrosis. Many of these features cause diagnostic confusion with embryonal carcinoma with solid growth pattern. A lack of diffuse immunoreactivity for PLAP and epithelial markers would support the diagnosis of anaplastic spermatocytic seminoma. These anaplastic changes probably represent dedifferentiation but do not seem to alter the biological behavior of the neoplasm.
Sarcomatous change	Sarcomatous change may rarely occur. The seminomatous and sarcomatous areas are intimately admixed, with no apparent morphologic transition between the two components. The sarcomatous elements have consisted of undifferentiated spindle cells or show rhabdomyosarcomatous differentiation. It is thought that it represents anaplastic transformation or dedifferentiation of a spermatocytic seminoma. The spermatocytic seminoma component has shown the usual histological features, except for an unusually high mitotic rate and frequent atypical mitotic figures in some cases. No other germ cell or teratomatous elements have been identified in any case. If present, this sarcomatous change leads to an aggressive course with extremely poor prognosis. Adjuvant chemotherapy seems to have no effect in the cases in which it has been tried. Fifty percent of patients die of metastases to lungs, liver, or retroperitoneum within in a few months.

SPECIAL STAINS/IMMUNOPEROXIDASE/ OTHER	CHARACTERIZATION
Immunoperoxidase	These tumors are typically negative for PLAP and HCG, unlike classic seminomas.

CHARACTERIZATION	SPERMATOCYTIC SEMINOMA	TYPICAL SEMINOMA
Proportion of germ cell tumors	1-2%	40-50%
Sites	Testis only	Testis, ovary, mediastinum, pineal, retroperitoneum
Bilaterality	9%	2%
Association with other forms of germ cell tumor	No	Yes
Association with IGCNU	No	Yes
Intercellular edema	Common	Uncommon
Composition	3 cell types, with denser cytoplasm, round nuclei	1 cell type, often clear cytoplasm, less regular nuclei
Stroma	Scanty	Prominent
Lymphoid reaction	Rare to absent	Prominent
Granulomas	Extremely rare	Often prominent
Sarcomatous transformation	Occasional	Absent
Glycogen	Absent to scant	Abundant
PLAP staining	Absent to scant	Prominent
hCG staining	Absent	Present in 10%
Metastases	Extremely rare	Common

ADDITIONAL DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
Lymphoma

PROGNOSIS AND TREATMENT	CHARACTERIZATION
Prognostic Factors
Survival	Excellent prognosis
Metastasis	There are only four reported cases of spermatocytic seminoma with metastases and the documentation in some of these cases is questionable leading to the current viewpoint that these tumors are best regarded as potentially capable of metastases.
Treatment	Radical orchiectomy usually resulting in cure Post-operative prophylactic radiation or chemotherpay do not offer any additional benefit and are not routinely recommended.