Which of the following is not related to increased risk of nephroblastoma?
Answer A
Nephroblastoma, or Wilms’ tumour, characteristically presents as a painless mass in an otherwise well pre-school child. In the UK, after staging imaging the diagnosis is made with biopsy. Treatment begins with chemotherapy, and is then followed by surgery. Further chemotherapy or radiotherapy may then follow.
The WT1 gene, predisposing to the Wilms’ tumour, lies on chromosome 11p13. Other genes predisposing to Wilms’ tumours have also been identified at 11p15 and 16q. Beckwith–Wiedemann syndrome is characterised by macroglossia, macrosomia, visceromegaly and midline abdominal wall defect such as omphalocele or exomphalos. It is associated with a significantly increased risk of developing Wilms’ tumour.
Perlman syndrome is another overgrowth syndrome associated with polyhydramnios during pregnancy, macrocephaly, macrosomia, visceromegaly and an increased risk for Wilms’ tumour. In Denys–Drash syndrome, the presence of nephropathy (mesangial sclerosis) and gonadal dysgenesis is associated with the development of Wilms’ tumour.
WAGR syndrome is characterised by increased predisposition to Wilms’ tumour, aniridia, genitourinary anomalies (typical tumours of the ovaries or testes) and ‘mental retardation’.
Which of the following is not present at the presentation of a child with bladder exstrophy?
Answer D
The abnormalities seen in bladder exstrophy represent a failure of development of the lower abdominal wall; possibly because of the failure of mesoderm to migrate into the cloacal membrane. In classic bladder exstrophy the abnormalities seen all follow from this failure. The bladder lies open and exposed as a bladder plate. The umbilicus lies immediately adjacent to the bladder plate. When the bladder plate is mobilised for closure the umbilicus becomes ischaemic and is subsequently lost. The ureters do not enter the bladder obliquely and there is an increased tendency to subsequent vesicoureteric reflux. There is diastasis of the pubic rami, (i.e., they fail to meet in the midline). The lower abdominal wall demonstrates a series of characteristic features: the rectus muscle divaricates inferiorly, the umbilicus is sited rather low, and the perineum is foreshortened resulting in a slightly anterior anus. The separated pubic rami result in the bony attachments of the corpora cavernosa being widely separated. This contributes to a rather short and wide penis in boys, and a bifid clitoris in girls. In contrast to cloacal exstrophy, there tend not to be other associated anomalies in classic bladder exstrophy, (i.e., there is no increased association with developmental problems, cardiac or spinal disease).
Although bladder exstrophy is a devastating anomaly of the lower urinary tract, the upper urinary tract is not usually affected at presentation. Closure of the abdominal wall and bladder are difficult. To achieve urinary continence, some mechanism to control the bladder outlet needs to be surgically created, as well as ensuring that the bladder has adequate storage. One of the most common ways of controlling the bladder outlet is to create a fixed resistance that then has to be overcome during voiding. Care of these complex patients is performed in specialist centres where the goal of urinary continence is perused without jeopardising the upper tracts.
Which of these do not occur in a child with a disorder of sexual differentiation?
Answer E
For those that do not practice in this area, disorders of sexual differentiation (DSD) can prove difficult to understand. It would seem unfair that someone taking the FRCS(Urol) would have a detailed knowledge of the classification of these conditions. A few basic principles will be outlined.
A very simplified account of the embryology of differentiation follows. The foetus will develop by default into a female. The mesonephric duct (precursors of uterus and upper vagina) are initially present in both males and females. Secretion of Müllerian Inhibiting Substance (MIS) from the Sertoli cells from 7 weeks will cause regression of the mesonephric duct structures in boys. Androgens, and especially dihydroxy-testosterone are responsible for the development of the external genitals in males.
A good starting point for classifying DSD is the karyotype. Those with 46XX who have DSD will be over-virilised; those with 46XY who have DSD will be under-virilised. This will be further complicated by mosaic karyotype patterns. The next consideration is the development of the gonads. Where gonads have formed abnormally there is gonadal dysgenesis. This may be complete or partial. It may result in streak gonads or in an ovo-testis combination.
Then next consideration is whether there is an abnormality in the synthesis of the sex-hormone or their receptor. In congenital adrenal hyperplasia, the production of cortisol and aldosterone is disrupted triggering over production of ACTH which then stimulates overproduction of androgenic precursors resulting in over virilisation of girls. Androgen receptor insensitivity and 5α reductase deficiency will on the other hand result in under-virilised boys.
Ovarian dysgenesis syndrome is also known as Turner’s syndrome. Dysgenetic streak ovaries are present but in the absence of a Y chromosome there is no cause for ambiguity about the appearance of the genitals.
Which of the following is not true, with respect to myelomeningocele?
The detrusor leak point pressure is the lowest pressure at which leaking occurs without detrusor contraction or rise in abdominal pressure. Pressures over 40 cm of water are associated with increased risk of upper tract damage.
Poor bladder emptying is most reliably managed with urethral intermittent catheterisation. This can be very daunting for the patient and the parents. However a good clinical nurse specialist can be surprisingly successful in even the most anxious children. Teaching clean intermittent catheterisation to the parents of all infants with myelomeningocele within the first year will avoid the problems of having to teach an older and more reluctant child. The first line treatment of detrusor over-activity is anti-muscarinic medication. Although oxybutynin is probably the most commonly used, tolterodine is also frequently effective.
Botulinum toxin is increasingly being used in the management of neurogenic detrusor overactivity. Treatment is administered under general anaesthesia, and requires repeating. It is best reserved for those who do not tolerate or respond to anti-muscarinics.
Ileocystoplasty is a very effective treatment of unsafe bladder storage. It is a significant undertaking. Those treated this way will have increase urinary mucus, and face increased risk of infection, stones, alkalosis, Vitamin B12 deficiency, bladder rupture and possibly malignancy. Although there is a risk of infection of ventriculoperitoneal shunt, this is not a contraindication to ileocystoplasty.
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