Hydatidiform mole
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2008-07-16T08:20:04Z
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{{Infobox_Disease
| Name = {{PAGENAME}}
| Image =
| Caption =
| DiseasesDB = 6097
| ICD10 = {{ICD10|O|01||o|00}}, {{ICD10|D|39|2|d|37}}
| ICD9 = {{ICD9|630}}
| ICDO = M9100
| OMIM = 231090
| MedlinePlus = 000909
| eMedicineSubj = med
| eMedicineTopic = 1047
| eMedicine_mult = {{eMedicine2|med|866}}
| MeshID = 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]].<ref>''Robbins and Cotran's Pathological Basis of Disease, 7th ed.'', p. 1110</ref> 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 language|Greek]] "a drop of water"), referring to the watery contents of the cysts, and ''mole'' (from [[Latin]] ''mola'' = millstone/false conception).<ref>Entries HYDATID ''n.'' (''a.'') and MOLE, ''n.''<sup>6</sup> in the [[Oxford English Dictionary]] online. (http://dictionary.oed.com/ — subscription required.)</ref>
==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 (biology)|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).<ref>{{cite journal |author=Di Cintio E, Parazzini F, Rosa C, Chatenoud L, Benzi G |title=The epidemiology of gestational trophoblastic disease |journal=Gen Diagn Pathol |volume=143 |issue=2-3 |pages=103–8 |year=1997 |pmid=9443567 |doi=}}</ref>
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]].<ref>[http://www.nlm.nih.gov/medlineplus/ency/article/000909.htm Hydatidiform mole], MedlinePlus Medical Encyclopedia. Accessed 23 November 2007</ref> 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.<ref>{{cite journal |author=Paoloni-Giacobino A. |title=Epigenetics in reproductive medicine |journal=Paediatr Res. |volume=May 61 |issue=5 Pt 2 |pages=51R–57R |year=2007 |pmid=17413849 |doi=}}</ref>
===Parental origin===
In most hydatidiform moles, the [[parental]] origin of the [[gene]]s in the cellular [[nucleus]] is abnormal.
In most complete moles, all [[nuclear gene]]s are inherited from the father, only ([[androgenesis]]). In approximately 80% of these androgenetic moles, the most probable mechanism is that an empty [[ovum|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 ''[[NLRP7]]'', predisposing them towards molar pregnancy. These rare variants of hydatidiform mole may be complete or partial. <ref>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]</ref> <ref>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]</ref> <ref>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]</ref>
In rare cases a hydatidiform mole co-exists in the uterus with a normal, viable fetus. These cases are due to [[twins|twinning]]. The uterus contains two conceptuses: One with an abnormal placenta and no viable fetus (the mole), and one with a normal placenta and a viable fetus. Under careful surveillance it is often possible to help the woman to giving birth of the child and being cured of mole.<ref>Sebire NJ, Foskett M, Paradinas FJ, Fisher RA, Francis RJ, Short D, Newlands ES, Seckl MJ. Outcome of twin pregnancies with complete hydatidiform mole and healthy co-twin. Lancet. 2002 Jun 22;359(9324):2165-6.
PMID: 12090984 [PubMed - indexed for MEDLINE]</ref>
==Clinical presentation and diagnosis==
Molar pregnancies usually present with painless vaginal bleeding in the fourth to fifth month of pregnancy.<ref>''Robbins and Cotran's Pathological Basis of Disease, 7th ed.'', p. 1110</ref> The [[uterus]] may be larger than expected, or the [[ovary|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).<ref>McPhee S. and Ganong W.F. ''Pathophysiology of Disease, 5th ed.'', p. 639.</ref>
The diagnosis is strongly suggested by ultrasound ([[medical ultrasonography|sonogram]]), but definitive diagnosis requires [[Histopathology | histopathological examination]]. The mole grossly resembles a bunch of grapes ("cluster of grapes" or "honeycombed uterus" or "snow-storm"<ref>{{cite journal |author=Woo J, Hsu C, Fung L, Ma H |title=Partial hydatidiform mole: ultrasonographic features |journal=Aust N Z J Obstet Gynaecol |volume=23 |issue=2 |pages=103–7 |year=1983 |pmid=6578773 |doi=10.1111/j.1479-828X.1983.tb00174.x}}</ref>). There is an increased [[trophoblast]] proliferation and enlargening of [[chorionic villi]].<ref name=oslo/> The [[angiogenesis]] in the trophoblasts are imparied as well. <ref name=oslo> [http://www.med.uio.no/studier/eksamen/medisin/sem9/oppgaver/2002/9-02-v-eng.rtf Oslo University] - Eksamensoppgaver i barnesykdommer; 9</ref>
Sometimes symptoms of [[hyperthyroidism]] are seen, due to the extremely high levels of hCG, which can mimic the normal [[Thyroid-stimulating hormone]] (TSH).<ref>McPhee S. and Ganong W.F. ''Pathophysiology of Disease, 5th ed.'', p. 639.</ref>
==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]].<ref>''Robbins and Cotran's Pathological Basis of Disease, 7th ed.'', p. 1112</ref> 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 [[fetus]]es.
[[Carboprost]] medication may be used to contract the [[uterus]].
==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 [[metastasis|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.
==References==
{{reflist}}
==See also==
*[[Gestational trophoblastic disease]]
==External links==
* Original source: http://www.nlm.nih.gov/medlineplus/ency/article/000909.htm
*[http://www.springerlink.com/link.asp?id=w2555w4k4805h4h9 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''
{{Pathology of pregnancy, childbirth and the puerperium}}
{{Soft tissue tumors and sarcomas}}
{{Pregnancy}}
[[Category:Oncology]]
[[Category:Obstetrics]]
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[[he:מולה (אנטומיה)]]
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