Dysgerminoma
Medical condition
From Wikipedia, the free encyclopedia
A dysgerminoma is a type of germ cell tumor;[1] it usually is malignant and usually occurs in the ovary.
| Dysgerminoma | |
|---|---|
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| Micrograph of a dysgerminoma, H&E stain. | |
| Specialty | Oncology, gynecology |
A tumor of the identical histology but not occurring in the ovary may be described by an alternate name: seminoma in the testis[2] or germinoma in the central nervous system or other parts of the body. Locations outside the ovaries such as the abdomen, fallopian tubes and uterus are rarely involved.[3][4][5]
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.[6]
Abnormal gonads (due to gonadal dysgenesis and androgen insensitivity syndrome) have a high risk[7] of developing a dysgerminoma. Most dysgerminomas are associated with elevated serum lactic dehydrogenase, which is sometimes used as a tumor marker.
Signs and symptoms
Abdominal pain or distention is the most common presenting symptom. They are exceptionally associated with hypercalcemia.[8] Paraneoplastic hypercalcemia mediated by ectopic 1,25-dihydroxyvitamin D production. Pseudo-Meigs Syndrome (PMS) may associated with dysgerminoma in exceedingly rare condition.PMS having clinical triad of a pelvic mass, massive ascites and hydrothorax/pleural effusion. Serum marker CA125 and β-hCG can be markedly elevated due to peritoneal irritation rather than primary tumor secretion.[9] On gross examination, dysgerminomas present with a smooth, bosselated (knobby) external surface, and are 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.
Molecular Genetics
At the molecular level, dysgerminomas closely resemble primordial germ cells, displaying a characteristic hypomethylated genomic profile.[10] A key cytogenetic feature present in the majority of dysgerminomas is the presence of isochromosome 12p. Pathogenetically, dysgerminomas frequently harbor gain-of-function activating mutations in the c-KIT (CD117) receptor tyrosine kinase gene.[11] Downstream activation of the RAS-MAPK and PI3K (phosphoinositide 3-kinase) cell-signaling pathways promotes the uncontrolled proliferation and survival of primitive germ cells. The tumor also exhibits high nuclear and cytoplasmic expression of pluripotency transcription factors including OCT3/4, SALL4, and SOX17.[12]
Diagnosis
Treatment
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.[13] Targeted treatments for dysgerminomas that do not respond to chemotherapy are being evaluated.[13]