Hydatidiform mole
From Wikipedia, the free encyclopedia
| Hydatidiform mole Classification and external resources |
|
| ICD-10 | O01., D39.2 |
|---|---|
| ICD-9 | 630 |
| ICD-O: | M9100 |
| OMIM | 231090 |
| DiseasesDB | 6097 |
| MedlinePlus | 000909 |
| eMedicine | med/1047 med/866 |
| MeSH | D006828 |
Molar pregnancy is an abnormal form of pregnancy, characterized by the presence of a hydatidiform mole (or hydatid mole, mola hytadidosa), an anomalous growth containing a nonviable embryo which implants and proliferates within the uterus.[1] In some cases the uterus contains a normal embryo in addition to the mole. A hydatidiform mole is removed upon diagnosis because there is some risk that it develop into choriocarcinoma, a form of cancer.
The term is derived from hydatis (Greek "a drop of water"), referring to the watery contents of the cysts, and mole (from Latin mola = millstone/false conception).[2]
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[edit] Natural history
A hydatidiform mole is a pregnancy/conceptus in which the placenta contains grapelike vesicles that are visible with the naked eye. The vesicles arise by distention of the chorionic villi by fluid. When inspected in the microscope, hyperplasia of the trophoblastic tissue is noted. If left untreated, a hydatidiform mole always ends as a spontaneous abortion.
Based on morphology, hydatidiform moles can be divided into two types: In complete moles, all the chorionic villi are vesicular, and no sign of embryonic or fetal development is present. In partial moles some villi are vesicular, whereas others appear more normal, and embryonic/fetal development may be seen but the fetus is always malformed and is never viable.
Hydatidiform moles are a common complication of pregnancy, occurring once in every 1000 pregnancies in the US, with much higher rates in Asia (e.g. up to one in 100 pregnancies in Indonesia).[3]
The etiology of this condition is not completely understood. Potential risk factors may include defects in the egg, abnormalities within the uterus, or nutritional deficiencies. Women under 20 or over 40 years of age have a higher risk. Other risk factors include diets low in protein, folic acid, and carotene.[4] The diploid set of sperm-only DNA means that all chromosomes have sperm-patterned methylation suppression of genes. This leads to overgrowth of the syncytiotrophoblast whereas dual egg-patterned methylation leads to a devotion of resources to the embryo, with an underdeveloped syncytiotrophoblast. This is considered to be the result of evolutionary competition with male genes driving for high investment into the fetus versus female genes driving for resource restriction to maximise the number of children.[5]
[edit] Parental origin
In most hydatidiform moles, the parental origin of the genes in the cellular nucleus is abnormal.
Most complete moles inherit their nuclear genes are inherited from the father only (androgenesis). In approximately 80% of these androgenetic moles, the most probable mechanism is that an empty egg is fertilized by a single sperm, followed by a duplication of all chromosomes/genes (a process called "endoreduplication"). In approximately 20% of complete moles the most probable mechanism is that an empty egg is fertilised by two sperms. In both cases, the moles are diploid (i.e. there are two copies of every chromosome). In all these cases, the mitochondrial genes are inherited from the mother, as usual.
Most partial moles are triploid (three chromosome sets). The most probable mechanism is that a normal haploid egg is fertilized by two sperms. Thus the nucleus contains one maternal set of genes and two paternal sets.
In rare cases, hydatidiform moles are tetraploid (four chromosome sets) or have other chromosome abnormalities.
A small percentage of hydatidiform moles have biparental diploid genomes, as in normal living persons; they have two sets of chromosomes, one inherited from each biological parent. Some of these moles occur in women who carry mutations in the gene NARP7, predisposing them towards molar pregnancy. These rare variants of hydatidiform mole may be complete or partial. [6] [7] [8]
[edit] Clinical presentation and diagnosis
Molar pregnancies usually present with painless vaginal bleeding in the fourth to fifth month of pregnancy.[9] The uterus may be larger than expected, or the ovaries may be enlarged. There may also be more vomiting than would be expected (hyperemesis). Sometimes there is an increase in blood pressure along with protein in the urine. Blood tests will show very high levels of human chorionic gonadotropin (hCG).[10]
The diagnosis is strongly suggested by ultrasound (sonogram), but definitive diagnosis requires histopathological examination. The mole grossly resembles a bunch of grapes ("cluster of grapes" or "honeycombed uterus" or "snow-storm"[11]). There is an increased trophoblast proliferation and enlargening of chorionic villi.[12] The angiogenesis in the trophoblasts are imparied as well. [12]
Sometimes symptoms of hyperthyroidism are seen, due to the extremely high levels of hCG, which can mimic the normal Thyroid-stimulating hormone (TSH).[13]
[edit] Treatment
Hydatidiform moles should be treated by evacuating the uterus by uterine suction or by surgical curettage as soon as possible after diagnosis, in order to avoid the risks of choriocarcinoma.[14] Patients are followed up until their serum human chorionic gonadotrophin (hCG) level has fallen to an undetectable level. Invasive or metastatic moles (cancer) may require chemotherapy and often respond well to methotrexate. The response to treatment is nearly 100%. Patients are advised not to conceive for one year after a molar pregnancy. The chances of having another molar pregnancy are approximately 1%.
Management is more complicated when the mole occurs together with one or more normal fetuses.
Carboprost medication may be used to contract the uterus.
[edit] Prognosis
More than 80% of hydatidiform moles are benign. The outcome after treatment is usually excellent. Close follow-up is essential. Highly effective means of contraception are recommended to avoid pregnancy for at least 6 to 12 months.
In 10 to 15% of cases, hydatidiform moles may develop into invasive moles. This condition is named persistent trophoblastic disesase (PTD). The moles may intrude so far into the uterine wall that hemorrhage or other complications develop. It is for this reason that a post-operative full abdominal and chest x-ray will often be requested.
In 2 to 3% of cases, hydatidiform moles may develop into choriocarcinoma, which is a malignant, rapidly-growing, and metastatic (spreading) form of cancer. Despite these factors which normally indicate a poor prognosis, the rate of cure after treatment with chemotherapy is high.
Over 90% of women with malignant, non-spreading cancer are able to survive and retain their ability to have children. In those with metastatic (spreading) cancer, remission remains at 75 to 85%, although the ability to have children is usually lost.
[edit] References
- ^ Robbins and Cotran's Pathological Basis of Disease, 7th ed., p. 1110
- ^ Entries HYDATID n. (a.) and MOLE, n.6 in the Oxford English Dictionary online. (http://dictionary.oed.com/ — subscription required.)
- ^ Di Cintio E, Parazzini F, Rosa C, Chatenoud L, Benzi G (1997). "The epidemiology of gestational trophoblastic disease". Gen Diagn Pathol 143 (2-3): 103–8. PMID 9443567.
- ^ Hydatidiform mole, MedlinePlus Medical Encyclopedia. Accessed 23 November 2007
- ^ Paoloni-Giacobino A. (2007). "Epigenetics in reproductive medicine.". Paediatr Res. May 61 (5 Pt 2): 51R-57R. PMID 17413849.
- ^ Lawler SD, Fisher RA, Dent J. A prospective genetic study of complete and partial hydatidiform moles. Am J Obstet Gynecol. 1991 May;164(5 Pt 1):1270-7. PMID: 1674641 [PubMed - indexed for MEDLINE]
- ^ Slim R, Mehio A. Wallace DC, Surti U, Adams CW, Szulman AE. Complete moles have paternal chromosomes but maternal mitochondrial DNA. Hum Genet. 1982;61(2):145-7. PMID: 6290372 [PubMed - indexed for MEDLINE]
- ^ Slim R, Mehio A. The genetics of hydatidiform moles: new lights on an ancient disease. Clin Genet. 2007 Jan;71(1):25-34. Review. PMID: 17204043 [PubMed - indexed for MEDLINE]
- ^ Robbins and Cotran's Pathological Basis of Disease, 7th ed., p. 1110
- ^ McPhee S. and Ganong W.F. Pathophysiology of Disease, 5th ed., p. 639.
- ^ Woo J, Hsu C, Fung L, Ma H (1983). "Partial hydatidiform mole: ultrasonographic features". Aust N Z J Obstet Gynaecol 23 (2): 103-7. doi:. PMID 6578773.
- ^ a b Oslo University - Eksamensoppgaver i barnesykdommer; 9
- ^ McPhee S. and Ganong W.F. Pathophysiology of Disease, 5th ed., p. 639.
- ^ Robbins and Cotran's Pathological Basis of Disease, 7th ed., p. 1112
[edit] See also
[edit] External links
- Original source: http://www.nlm.nih.gov/medlineplus/ency/article/000909.htm
- Complete moles have paternal chromosomes but maternal mitochondrial DNA by Douglas C. Wallace, Urvashi Surti, Camellia W. Adams and A. E. Szulman, Volume 61, Number 2 of Human Genetics
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