Intracranial germinoma occurs in 0.7 per million children. As with other germ cell tumors (GCTs) occurring outside the gonads, the most common location of intracranial germinoma is on or near the midline, often in the pineal or suprasellar areas; in 5-10% of patients with germinoma in either area, the tumor is in both areas. Like other (GCTs), germinomas can occur in other parts of the brain. Within the brain, this tumor is most common in the hypothalamic or hypophyseal regions. In the thalamus and basal ganglia, germinoma is the most common GCT.

The diagnosis of an intracranial germinoma usually is based on biopsy, as the features on neuroimaging appear similar to other tumors.

Cytology of the CSF often is studied to detect metastasis into the spine. This is important for staging and radiotherapy planning.

Intracranial germinomas have a reported 90% survival to five years after diagnosis. Near total resection does not seem to influence the cure rate, so gross total resection is not necessary and can increase the risk of complications from surgery. The best results have been reported from craniospinal radiation with local tumor boost of greater than 4,000 cGy.

Germinomas, like several other types of germ cell tumor, are sensitive to both chemotherapy and radiotherapy. For this reason, treatment with these methods can offer excellent chances of longterm survival, even cure.

Although chemotherapy can shrink germinomas, it is not generally recommended alone unless there are contraindications to radiation. In a study in the early 1990s, carboplatinum, etoposide and bleomycin were given to 45 germinoma patients, and about half the patients relapsed. Most of these relapsed patients were then recovered with radiation or additional chemotherapy.

Blood tests may detect the presence of placental alkaline phosphatase (PLAP) in fifty percent of cases. However, PLAP cannot usefully stand alone as a marker for seminoma and contributes little to follow-up, due to its rise with smoking. 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. A classical or pure seminoma by definition do not cause an elevated serum alpha fetoprotein . Lactate dehydrogenase (LDH) may be the only marker that is elevated in some seminomas. The degree of elevation in the serum LDH has prognostic value in advanced seminoma.

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 hemorrhage may be seen. These areas of hemorrhage usually correspond to trophoblastic cell clusters within the tumour.

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 septa 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 spermatocytic maturation arrest.

POU2AF1 and PROM1 have been proposed as possible markers.

The 1997 International Germ Cell Consensus Classification is a tool for estimating the risk of relapse after treatment of malignant germ cell tumor.

A small study of ovarian tumors in girls reports a correlation between cystic and benign tumors and, conversely, solid and malignant tumors. Because the cystic extent of a tumor can be estimated by ultrasound, MRI, or CT scan before surgery, this permits selection of the most appropriate surgical plan to minimize risk of spillage of a malignant tumor.

Access to appropriate treatment has a large effect on outcome. A 1993 study of outcomes in Scotland found that for 454 men with non-seminomatous (non-germinomatous) germ cell tumors diagnosed between 1975 and 1989, 5-year survival increased over time and with earlier diagnosis. Adjusting for these and other factors, survival was 60% higher for men treated in a cancer unit that treated the majority of these men, even though the unit treated more men with the worst prognosis.

Choriocarcinoma of the testicles has the worst prognosis of all germ cell cancers

Intratesticular masses that appear suspicious on an ultrasound should be treated with an inguinal orchiectomy. The pathology of the removed testicle and spermatic cord indicate the presence of the seminoma and assist in the staging. Tumors with both seminoma and nonseminoma elements or that occur with the presence of AFP should be treated as nonseminomas. Abdominal CT or MRI scans as well as chest imaging are done to detect for metastasis. The analysis of tumor markers also helps in staging.

The preferred treatment for most forms of stage 1 seminoma is active surveillance. Stage 1 seminoma is characterized by the absence of clinical evidence of metastasis. Active surveillance consists of periodic history and physical examinations, tumor marker analysis, and radiographic imaging. Around 85-95% of these cases will require no further treatment. Modern radiotherapy techniques as well as one or two cycles of single-agent carboplatin have been shown to reduce the risk of relapse, but carry the potential of causing delayed side effects. Regardless of treatment strategy, stage 1 seminoma has nearly a 100% cure rate.

Stage 2 seminoma is indicated by the presence of retroperitoneal metastasis. Cases require radiotherapy or, in advanced cases, combination chemotherapy. Large residual masses found after chemotherapy may require surgical resection. Second-line treatment is the same as for nonseminomas.

Stage 3 seminoma is characterized by the presence of metastasis outside the retroperitoneum—the lungs in "good risk" cases or elsewhere in "intermediate risk" cases. This is treated with combination chemotherapy. Second-line treatment follows nonseminoma protocols.

Dysgerminomas, like other seminomatous germ cell tumors, are very sensitive to both chemotherapy and radiotherapy. For this reason, with treatment patients' chances of long-term survival, even cure, is excellent.

While cancer is generally considered a disease of old age, children can also develop cancer. In contrast to adults, carcinomas are exceptionally rare in children..

The two biggest risk factors for ovarian carcinoma are age and family history.

Women with benign germ cell tumors such as mature teratomas (dermoid cysts) are cured by ovarian cystectomy or oophorectomy. In general, all patients with malignant germ cell tumors will have the same staging surgery that is done for epithelial ovarian cancer. If the patient is in her reproductive years, an alternative is unilateral salpingoophorectomy, while the uterus, the ovary, and the fallopian tube on the opposite side can be left behind. This isn't an option when the cancer is in both ovaries. If the patient has finished having children, the surgery involves complete staging including salpingoophorectomy on both sides as well as hysterectomy.

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).

Grading of carcinomas refers to the employment of criteria intended to semi-quantify the degree of cellular and tissue maturity seen in the transformed cells relative to the appearance of the normal parent epithelial tissue from which the carcinoma derives.

Grading of carcinoma is most often done after a treating physician and/or surgeon obtains a sample of suspected tumor tissue using surgical resection, needle or surgical biopsy, direct washing or brushing of tumor tissue, sputum cytopathology, etc. A pathologist then examines the tumor and its stroma, perhaps utilizing staining, immunohistochemistry, flow cytometry, or other methods. Finally, the pathologist classifies the tumor semi-quantitatively into one of three or four grades, including:

- Grade 1, or well differentiated: there is a close, or very close, resemblance to the normal parent tissue, and the tumor cells are easily identified and classified as a particular malignant histological entity;

- Grade 2, or moderately differentiated: there is considerable resemblance to the parent cells and tissues, but abnormalities can commonly be seen and the more complex features are not particularly well-formed;

- Grade 3, or poorly differentiated: there is very little resemblance between the malignant tissue and the normal parent tissue, abnormalities are evident, and the more complex architectural features are usually rudimentary or primitive;

- Grade 4, or undifferentiated carcinoma: these carcinomas bear no significant resemblance to the corresponding parent cells and tissues, with no visible formation of glands, ducts, bridges, stratified layers, keratin pearls, or other notable characteristics consistent with a more highly differentiated neoplasm.

Although there is definite and convincing statistical correlation between carcinoma grade and tumor prognosis for some tumor types and sites of origin, the strength of this association can be highly variable. It may be stated generally, however, that the higher the grade of the lesion, the worse is its prognosis.

A dysgerminoma is a type of germ cell tumor; it usually is malignant and usually occurs in the ovary.

A tumor of the identical histology but not occurring in the ovary may be described by an alternate name: seminoma in the testis or germinoma in the central nervous system or other parts of the body.

Dysgerminoma accounts for less than 1% of ovarian tumors overall. Dysgerminoma usually occurs in adolescence and early adult life; about 5% occur in pre-pubertal children. Dysgerminoma is extremely rare after age 50. Dysgerminoma occurs in both ovaries in 10% of patients and, in a further 10%, there is microscopic tumor in the other ovary.

Abnormal gonads (due to gonadal dysgenesis and androgen insensitivity syndrome) have a high risk of developing a dysgerminoma. Most dysgerminomas are associated with elevated serum lactic dehydrogenase (LDH), which is sometimes used as a tumor marker.

Pinealomas can be due to proliferation of primary pineocytes (pineocytomas, pineoblastomas), astrocytes (astrocytoma), or germ cells (germinoma). Germinomas are the most common tumor in the pineal gland.

A pinealoma is a tumor of the pineal gland, a part of the brain that produces melatonin. If a pinealoma destroys the cells of the pineal gland in a child, it can cause precocious puberty.