Dysgerminoma


Dysgerminoma

Description, Causes and Risk Factors:

A malignant neoplasm of the ovary (counterpart of seminoma of the testis), composed of undifferentiated gonadal germinal cells and occurring more frequently in patients less than 20 years of age. The neoplasms are gray-yellow and firm, contain foci of necrosis and hemorrhage, and tend to be encapsulated; characteristically, they spread by way of lymphatic vessels, but widespread metastases also occur.

Dysgerminoma

A dysgerminoma is a malignant tumor of the ovary that is composed of primitive, undifferentiated germ cells. Of the germ cell ovarian tumors, 97% are benign (i.e. mature teratomas) and the remaining 3% are malignant. Primitive unipotent germ cells are the precursors to ovarian dysgerminomas and their testicular analog, the seminoma, while pleuripotential germ cells divulge along different lines of differentiation such as choriocarcinoma, york sac, polyembryona tumors, teratomas.

The exact etiology of dysgerminomas has not been determined, although recent molecular studies have implicated loss of function with potential tumor suppressor gene TRC8/RNF139 as a possible etiology. Additionally, 5% of all dysgerminomas occur in dysgenetic gonads and may be associated with gonadoblastomas.

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.

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.

Symptoms:

The symptoms can be summarized as:

    Asymptomatic in early stages of growth and development.

  • Pelvic pain.

  • Excessive and abnormal bleeding during menstruation.

  • Dysuria.

  • Increased frequency of urination.

  • Mild abdominal symptoms.

  • Pelvic mass or pelvic fullness.

  • There may also be early satiety, urinary frequency and dysuria.

Diagnosis:

Regardless of the clinical environment, obtain a urine pregnancy test. This test should be mandatory in any woman of reproductive age who presents with abdominopelvic symptoms. Document a guaiac test during the physical examination.

Useful tumor markers for dysgerminomas may include:

    bHCG (beta human chorionic gonadotropin)

  • AFP (alpha-fetoprotein).

  • LDH (Lactate dehydrogenase).

  • Cancer antigen 125 (CA125)

  • These markers also can be used for postoperative follow-up care or for tracking the success of adjuvant therapy.

Imaging Studies:

    Imaging should never replace a careful history and physical examination in evaluating a patient with an ovarian mass. The initial approach should be an attempt to determine the nature and extent of the mass. Transvaginal ultrasound is a good preliminary imaging modality to determine if the mass is ovarian and, more importantly, if it has any malignant features (eg, thickened septations, solid and cystic components). Free abdominal fluid and bilateral masses heighten the suspicion of malignancy.

  • Secondary imaging studies are used to rule out metastasis.

  • Chest x-rays are performed to rule out pulmonary spread.

  • Depending on the age of the patient, a preoperative mammogram is suggested to rule out primary metastasis if no study was performed 6-12 months before surgery.

Body imaging with CT scanning and MRI can be of value in patients with GI or genitourinary signs of obstruction. In these cases, additional studies also include the following:

    Barium enema.

  • Upper GI series.

  • Colonoscopy.

  • Intravenous pyelography (IVP).

Bedside ultrasonography concomitant with the physical examination, although helpful, is not indicated as a routine screening test.

Treatment:

The treatment of patients with dysgerminoma is primarily surgical, including the resection of the primary lesion and proper surgical staging. If necessary, radiation or chemotherapy is administered to selected patients. Because the disease principally affects young females, special consideration must be given to the preservation of fertility whenever possible.

Ideally, the initial operation should include exploration of the abdominal contents, with careful palpation of the retroperitoneal node-bearing areas, sampling of enlarged nodes, and cytologic examination of peritoneal washings. If these steps were omitted in what was apparently stage I disease, the need for re-exploration for restaging purposes is questionable, simply because noninvasive imaging techniques are capable of detecting disease of less than 5 cm, which is highly curable, unlike the cystadenocarcinomas. For the same reason, biopsy of nonpalpable lymph nodes is probably unnecessary. A benefit of cytoreductive surgery has not been shown in this disease.

The minimum operation for ovarian dysgerminoma is a unilateral oophorectomy or salpingo-oophorectomy. If there is a desire to preserve fertility, the contralateral ovary, fallopian tube, and uterus should be conserved. This is probably true even in the presence of metastatic disease, because of the sensitivity of the tumor to chemotherapy. In patients whose fertility need not be preserved, it is appropriate to perform a total abdominal hysterectomy and bilateral salpingo-oophorectomy. In patients whose karyotype analysis reveals a Y chromosome, both ovaries should be removed, although the uterus might be conserved for possible future embryo transfer. Dysgerminoma is the only germ cell tumor that tends to be bilateral, and not all of the bilateral lesions have obvious ovarian enlargement. Therefore, bisection of the contralateral ovary and excisional biopsy of any suspicious lesion are desirable.

Postoperative workup should include the serum markers AFP and ?-hCG, a chest radiograph, and an abdominopelvic CT or MRI scan. In premenarchal females with an ovarian mass, preoperative karyotyping should be performed, as detection of a Y chromosome is an indication for bilateral oophorectomy, as discussed below. Even with a histologic diagnosis of pure dysgerminoma, the presence of an elevated AFP value or a markedly elevated ?-hCG level (over approximately 100 IU/L), indicates the presence of nondysgerminomatous elements, and is reason enough to base treatment on these more aggressive elements. As with seminoma, lower ?-hCG levels are sometimes found in the pure form of the disease, produced by syncytial-like giant interstitial cells. Lymphography can be useful, both in detecting nodal involvement and in localizing the nodal chains for radiation treatment.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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