Spermatocytic seminoma is a rare tumour, making up only one to two percent of all testicular germ cell tumours. Men presenting with this tumour are generally 50 to 60 years old, and its occurrence is rare in men under 30 years old. Most present with slow, painless testicular enlargement, which may involve both testes.

Not all germ cell tumors (GCTs) arise from "intratubular germ cell neoplasia". The following testicular GCTs do not arise from ITGCN:

- Spermatocytic seminoma

- Pediatric Yolk sac tumors (endodermal sinus tumour). This is currently an area of controversy as some authors dispute the absence of ITGCN in these cases.

- Teratoma (rare exceptions)

GCNIS is seen in the following settings:

- Almost all invasive germ cell tumours of the testis in adults

- Fifty percent of patients with GCNIS developed invasive germ cell tumours within five years of initial diagnosis.

- Five percent of contralateral testes in men with a history of prior testicular germ cell tumour.

- Less than five percent of cryptorchid testes.

- Less than one percent of patients with infertility.

Spermatocytic seminoma is a neoplasm of the testis ("i.e." a tumour of the testis), and classified as a germ cell tumour.

The name of the tumour comes from the similarity (under the microscope) between the small cells of the tumour and secondary spermatocytes.

There are few early warning signs that a patient has a DSRCT. Patients are often young and healthy as the tumors grow and spread uninhibited within the abdominal cavity. These are rare tumors and symptoms are often misdiagnosed by physicians. The abdominal masses can grow to enormous size before being noticed by the patient. The tumors can be felt as hard, round masses by palpating the abdomen.

First symptoms of the disease often include abdominal distention, abdominal mass, abdominal or back pain, gastrointestinal obstruction, lack of appetite, ascites, anemia, and/or cachexia.

Other reported symptoms include unknown lumps, thyroid conditions, hormonal conditions, blood clotting, kidney or urological problems, testicle, breast, uterine, vaginal, or ovarian masses.

They are exceptionally associated with hypercalcemia. On gross examination, dysgerminomas present with a smooth, bosselated (knobby) external surface, and is soft, fleshy and either cream-coloured, gray, pink or tan when cut. Microscopic examination typically reveals uniform cells that resemble primordial germ cells. Typically, the stroma contains lymphocytes and about 20% of patients have sarcoid-like granulomas.

Metastases are most often present in the lymph nodes.

Ewing's sarcoma is more common in males (1.6 male:1 female) and usually presents in childhood or early adulthood, with a peak between 10 and 20 years of age. It can occur anywhere in the body, but most commonly in the pelvis and proximal long tubular bones, especially around the growth plates. The diaphyses of the femur are the most common sites, followed by the tibia and the humerus. Thirty percent are overtly metastatic at presentation. Patients usually experience extreme bone pain.

Signs and symptoms include: intermittent fevers, anemia, leukocytosis, increased sedimentation rate, and other symptoms of inflammatory systemic illness. Also, depending on the type, progression, and location of the tumor, great pain may occur.

According to the Bone Cancer Research Trust (BCRT), the most common symptoms are: localized pain, swelling, and sporadic bone pain with variable intensity. The swelling is most likely to be visible if the sarcoma is located on a bone near the surface of the body, but when it occurs in other places deeper in the body, like on the pelvis, it may not be visible.

Synovial sarcoma usually presents with an otherwise asymptomatic swelling or mass, although general symptoms related to malignancies can be reported such as fatigue.

In the testis pure embryonal carcinoma is also uncommon, and accounts for approximately ten percent of testicular germ cell tumours. However, it is present as a component of almost ninety percent of mixed nonseminomatous germ cell tumours. The average age at diagnosis is 31 years, and typically presents as a testicular lump which may be painful. One fifth to two thirds of patients with tumours composed predominantly of embryonal carcinoma have metastases at diagnosis.

In the ovary, embryonal carcinoma is quite rare, amounting to approximately three percent of ovarian germ cell tumours. The median age at diagnosis is 15 years. Symptoms and signs are varied, and may include sexual precocity and abnormal (increased, reduced or absent) uterine bleeding.

There may be elevations in serum human chorionic gonadotropin (hCG) and alpha fetoprotein (AFP) levels but it would be in association with other tumors, (e.g. yolk sac tumor) because they themselves do not produce the serum markers. At surgery, there is extension of the tumour beyond the ovary in forty percent of cases. They are generally large, unilateral tumours, with a median diameter of 17 centimetres. Long-term survival has improved following the advent of chemotherapy. The gross and histologic features of this tumour are similar to that seen in the testis.

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.

It presents as a slow growing mass that especially affects tendons and aponeuroses and it is deeply situated. Patients often perceive it as a lump or hard mass. It causes either pain or tenderness but only until it becomes large enough. This kind of tumor is commonly found in the extremities especially around the knee, feet and ankle. Patients diagnosed with clear cell sarcoma are usually between the ages of 20 and 40.

Commonly affected areas include the lower limbs, back, face, mouth, and genitalia. The lesions are usually as described above, but may occasionally be plaque-like (often on the soles of the feet) or even involved in skin breakdown with resulting fungating lesions.

Associated swelling may be from either local inflammation or lymphoedema (obstruction of local lymphatic vessels by the lesion). Skin lesions may be quite disfiguring for the sufferer, and a cause of much psychosocial pathology.

Despite their name, germ cell tumors occur both within and outside the ovary and testis.

- head

- inside the cranium — pineal and suprasellar locations are most commonly reported

- inside the mouth — a fairly common location for teratoma

- neck

- mediastinum — account for 1% to 5% of all germ cell neoplasms

- pelvis, particularly sacrococcygeal teratoma

- ovary

- testis

In females, germ cell tumors account for 30% of ovarian tumors, but only 1 to 3% of ovarian cancers in North America. In younger women germ cell tumors are more common, thus in patients under the age of 21, 60% of ovarian tumors are of the germ cell type, and up to one-third are malignant. In males, germ cell tumors of the testis occur typically after puberty and are malignant (testicular cancer). In neonates, infants, and children younger than 4 years, the majority of germ cell tumors are sacrococcygeal teratomas.

Males with Klinefelter syndrome have a 50 times greater risk of germ cell tumors (GSTs). In these persons, GSTs usually contain nonseminomatous elements, present at an earlier age, and seldom are gonadal in location.

Congenital mesoblastic nephroma typically (76% of cases) presents as an abdominal mass which is detected prenatally (16% of cases) by ultrasound or by clinical inspection (84% of cases) either at birth or by 3.8 years of age (median age ~1 month). The neoplasm shows a slight male preference. Concurrent findings include hypertension (19% of cases), polyhydramnios (i.e. excess of amniotic fluid in the amniotic sac) (15%), hematuria (11%), hypercalcemia (4%), and elevated serum levels of the kidney-secreted, hypertension-inducing enzyme, renin (1%). Congenital anomalies have been reported in 11 patients: 6 with genitourinary anomalies, 2 with gastrointestinal anomalies, 1 with hydrocephalus, and 1 with the Beckwith–Wiedemann syndrome. The vast majority of patients present with localized (i.e. non-metastatic) disease. Most patients' disease is classified at presentation as stage I or II (i.e. localized), few patients present with stage III (i.e. locally advanced/infiltrating), and virtually no patients present with stage IV (metastases present or V (i.e. tumors in both kidneys) disease (see staging of renal cancer).

Endometrial stromal sarcoma is a malignant subtype of endometrial stromal tumor arising from the stroma (connective tissue) of the endometrium rather than the glands. There are three grades for endometrial stromal tumors, as follows. It was previously known as "endolymphatic stromal myosis" because of diffuse infiltration of myometrial tissue or the invasion of lymphatic channels.

Undifferentiated pleomorphic sarcoma (UPS), also undifferentiated pleomorphic sarcoma (PUS) and previously malignant fibrous histiocytoma (abbreviated MFH), is a type of cancer and soft tissue sarcoma.

It is considered a diagnosis of exclusion for sarcomas that cannot be more precisely categorized. Other sarcomas are cancers that form in bone and soft tissues, including muscle, fat, blood vessels, lymph vessels, and fibrous tissue (such as tendons and ligaments).

Ewing sarcoma or Ewing's sarcoma () is a malignant small, round, blue cell tumor. It is a rare disease in which cancer cells are found in the bone or in soft tissue. The most common areas in which it occurs are the pelvis, the femur, the humerus, the ribs and clavicle (collar bone).

Since a common genetic locus is responsible for a large percentage of Ewing sarcoma and primitive neuroectodermal tumors, these are sometimes grouped together in a category known as the Ewing family of tumors.

Ewing sarcoma occurs most frequently in teenagers and young adults, with a male/female ratio of 1.6:1.

Although usually classified as a bone tumor, Ewing's sarcoma can have characteristics of both mesodermal and ectodermal origin, making it difficult to classify.

James Ewing (1866–1943) first described the tumour, establishing that the disease was separate from lymphoma and other types of cancer known at that time.

A splenic tumor is a rare form of tumor that may be malignant or benign. Malignant forms include lymphoma and sarcoma.

Lymphoma is the most common malignant splenic tumor.

Desmoplastic small-round-cell tumor is an aggressive and rare cancer that primarily occurs as masses in the abdomen. Other areas affected may include the lymph nodes, the lining of the abdomen, diaphragm, spleen, liver, chest wall, skull, spinal cord, large intestine, small intestine, bladder, brain, lungs, testicles, ovaries, and the pelvis. Reported sites of metastatic spread include the liver, lungs, lymph nodes, brain, skull, and bones.

The tumor is classified as a soft tissue sarcoma. It is considered a childhood cancer that predominantly strikes boys and young adults. The disease rarely occurs in females, but when it does the tumors can be mistaken for ovarian cancer.

In dogs, mast cell tumors are the most frequent round cell tumor.

A germ cell tumor (GCT) is a neoplasm derived from germ cells. Germ cell tumors can be cancerous or non-cancerous tumors. Germ cells normally occur inside the gonads (ovary and testis). Germ cell tumors that originate outside the gonads may be birth defects resulting from errors during development of the embryo.

Choriocarcinoma is a malignant, trophoblastic cancer, usually of the placenta. It is characterized by "early hematogenous spread" to the lungs. It belongs to the malignant end of the spectrum in gestational trophoblastic disease (GTD). It is also classified as a germ cell tumor and may arise in the testis or ovary.

A synovial sarcoma (also known as: malignant synovioma) is a rare form of cancer which occurs primarily in the extremities of the arms or legs, often in close proximity to joint capsules and tendon sheaths. As one of the soft tissue sarcomas, it is one of the rarest forms of soft tissue cancer.

The name "synovial sarcoma" was coined early in the 20th century, as some researchers thought that the microscopic similarity of some tumors to synovium, and its propensity to arise adjacent to joints, indicated a synovial origin; however, the actual cells from which the tumor develops are unknown and not necessarily synovial.

Primary synovial sarcomas are most common in the soft tissue near the large joints of the arm and leg but have been documented in most human tissues and organs, including the brain, prostate, and heart.

Synovial sarcoma occurs most commonly in the young, representing

about 8% of all soft tissue sarcomas but about 15–20% of cases occur in adolescents and young adults. The peak of incidence is in the third decade of life, with males being affected more often than females (ratio around 1.2:1).

KS lesions are nodules or blotches that may be red, purple, brown, or black, and are usually papular.

They are typically found on the skin, but spread elsewhere is common, especially the mouth, gastrointestinal tract and respiratory tract. Growth can range from very slow to explosively fast, and is associated with significant mortality and morbidity.

A sarcoma is a cancer that arises from transformed cells of mesenchymal origin. Thus, malignant tumors made of cancellous bone, cartilage, fat, muscle, vascular, or hematopoietic tissues are, by definition, considered sarcomas. This is in contrast to a malignant tumor originating from epithelial cells, which are termed carcinoma. Human sarcomas are quite rare. Common malignancies, such as breast, colon, and lung cancer, are almost always carcinoma. The term is from the Greek "sarx" meaning "flesh".