Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

GYNAECOLOGICAL AND OBSTETRIC IMAGING
Year
: 2004  |  Volume : 14  |  Issue : 3  |  Page : 269--271

Meckel syndrome - a case report


SS Pawar, SD Pawar, VB Aundhekar, GA Vaidya, SG Sampatkumar, DM Joshi 
 Dept. of Radiodiagnosis and Imaging, B.J. Medical College and Sassoon General Hospitals, Pune-1, India

Correspondence Address:
S S Pawar
A-14, 17 Queen«SQ»s Garden, Pune 1
India




How to cite this article:
Pawar S S, Pawar S D, Aundhekar V B, Vaidya G A, Sampatkumar S G, Joshi D M. Meckel syndrome - a case report.Indian J Radiol Imaging 2004;14:269-271


How to cite this URL:
Pawar S S, Pawar S D, Aundhekar V B, Vaidya G A, Sampatkumar S G, Joshi D M. Meckel syndrome - a case report. Indian J Radiol Imaging [serial online] 2004 [cited 2019 Oct 21 ];14:269-271
Available from: http://www.ijri.org/text.asp?2004/14/3/269/28601


Full Text

Meckel Syndrome (MS) is a rare and lethal syndrome characterized by a triad of occipital cephalocele, post axial polydactyly and dysplastic cystic kidneys. Here we present a case of MS which had all the features constituting the triad.

 Case Report



A 23 year old primi with a history of consanginous marriage was referred for routine obstetric ultrasound. US evaluation revealed a single, live fetus of 22 - 23 weeks maturity with scanty liquor. US of the fetal abdomen revealed bilateral enlarged echogenic kidneys with few cystic spaces. [Figure 1]a and 1b. Fetal head showed a large occipital cephalocele. [Figure 2] Fetal thorax and liver were compressed by the enlarged kidneys. However fetal liver did not show cysts. Fetal urinary bladder was not visualized. Detection of bilateral dysplastic kidneys and an occipital cephalocele hinted to the diagnosis of MS and an attempt was made to look for polydactyly but could not be convincingly established due to scanty liquor. The umbilical cord had a normal trivascular appearance.

In view of the two lethal anomalies the patient was advised termination of pregnancy and genetic counselling.

Radiograph of the autopsy specimen revealed polysyndactyly, occcipital cephalocele, a bell shaped thorax and bowed bones. [Figure 3] Clinical examination revealed normal facial features and normal female external genitalia.

The finding of polysyndactyly in the autopsy specimen confirmed the diagnosis of MS.

 DISCUSSION



As described above in the introduction MS is a rare, lethal syndrome characterized by occipital cephalocele, post axial polydactyly and dysplastic cystic kidneys. It is also known by the synonyms Dysencephalia Splanchnocystica, Gruber Syndrome used in European literature - [1] and Meckel Gruber Syndrome in some texts [2].

A wide variety of rare inherited syndromes and genetic and chromosomal disorders are associated with cystic kidneys of which MS is one [2].

MS is an autosomal recessive disorder carrying a 25% risk of recurrence in future pregnancies[2,3]. The exact incidence is not known, but all authors agree that this is a very rare condition. Stated in figures it appears to be between 0.2 to 0.7 per 10,000 live births. In Finland this disorder is unusually frequent and reaches 1.1 per 10,000 live births. The locus for MS is on chromosome 17, long arm, region 2, bands 1- 4 [1].

To make the diagnosis of MS cystic dysplastic kidneys is an essential component of the triad in addition to two other minor defects [2]. Second component of the triad is an occipital cephalocele. Cephaloceles are seen in 60 - 80% of the cases [1],[2],[3],[4]. This component may be responsible for the minimal amount of liquor in these patients which would otherwise have been absent in patients of bilateral cystic dysplastic kidneys. Maternal serum or amniotic fluid - Alpha fetoprotein levels may be normal as the cephaocele may be covered by a membrane. Other CNS anomalies which may be found are microcephaly, holo prosencephaly, cerebral and cerebellar hypoplasia, hypoplasia of the pituitary gland and Dandy Walker malformation [1].

The third component of the triad is post axial polydactyly which is present in 55 - 77% of the cases [1],[2],[3],[4]. Other skeletal manifestations include short limbs, bowed limbs, talipes, bell shaped thorax, syndactyly, club foot and clinodactyly[1].

Finding atleast two of the three features of the triad in the presence of normal karyotype makes the diagnosis [1],[2],[3].

The constellation of possible associated anomalies is extensive and may make the recognition of the syndrome difficult. Associated anomalies include cleft lip / palate, micrognathia, ear anomalies, micro-opthalamia, epicanthic folds, nasal anomalies, hypo / hypertelorism, lobulated tongue, cleft epiglottis and neonatal teeth [1]. Most of these anomalies represent the Potter sequence which is thought to be due to severe oligohydramnios [4].

Clasically the renal anomaly which is present in MS is cystic dysplastic kidneys. However other renal anomalies may be found like bilateral renal agenesis, renal hypoplasia, horse shoe kidneys or double ureter.

Hepatic and portal fibrosis is one of the commonest associations [1].

Genital abnormalities include hypoplasia, ambigous genitalia, hermaphroditism and cryptorchidism [1],[2],[3],[4].

Cardiac abnormalities which are found include ventricular and atrial septal defects, coarctation / hypoplasia of the aorta, aortic valvular stenosis, pulmonary stenosis and rotational anomalies. [1]

Lungs may be hypoplastic. As with other syndromes MS may be associated with gut anomalies like omphaloceles, single umbilical artery, enlarged placenta and growth restriction [1].

Sonography of the fetal abdomen reveals bilateral reniform enlargement of the kidneys with poor delineation of intra renal structures. Most of the cysts are smaller than the limit of sonographic resolution. But they create multiple acoustic interfaces responsible for the characteristic increased echogenecity. Few scattered cysts may be identified. This appearance is essentially due to autosomal recessive (infantile) polycystic kidney disease (ARPKD) which can be diagnosed as early as 16 weeks due to scanty liquor. However, due to variability in expression and gestational age at onset, the kidneys may look normal initially only to become abnormal at a later date. Thus, a normal sonogram in a fetus with a risk for ARPKD, does not exclude the disease, making early prenatal diagnosis difficult in a few cases. Usually a follow up at 24 - 26 weeks is helpful in sorting out the problem. [2].

Differential diagnosis will depend on the type of associated anomalies. As the spectrum of anomalies overlaps with those of Trisomy13, karyotyping is essential. A normal karyotype points towards MS [1]. Asphyxiating thoracic dystrophy (Jeune Syndrome) Lawrence - Moon - Bardet - Biedl Syndrome, Short rib polydactyly syndromes and Cerebro - Hepto - Renal Syndrome (Zellweger Syndrome) figure in the differentials, as all these are autosomal recessive disorders associated with renal cysts [2]. Autosomal dominant polycystic kidney disease is another possible differential [1].

Prognosis in MS is bad. Most infants are still born or die hours or days after birth. Longest survivor reported in an atypical case died at 18 months. [1]

As regards management, when MS is suspected, a karyotype study is required to exclude chromosomal disorders. [1]

Our case was unique in that it had all the features of the triad of MS.

References

1S.R Silva, P. Jeanty. Fetal Syndromes. In P W Callen. Ultrasonography in Obstetrics and Gynaecology, 4th ed. Philadelphia: WB Saunders, 2000: 53, 93-94.
2K.W. Fong, G. Ryan. The Fetal Urogenital Tract. In C.M. Rumack, S.R. Wilson, J.W. Charboneau. Diagnostic Ultrasound. Vol. 2, 2nd ed. St. Louis: Mosby, 1998: 1110 - 1114.
3K. Dewbery, H. Meirre, D. Cosgrove. Ultrasound in Obstetrics and Gynaecology, 2nd ed. Churchill Livingstone: Edinburgh, 1993: 276 - 278, 298, 323, 399, 425, 487.
4R Romero, G. Pilu, P. Jeanty, A Ghidini, JC Hobbins. Prenatal Diagnosis of Congenital Anomalies, 1st ed. Norwalk: Appleton and Lange, 1998: 46, 261, 266 - 274.