AN ABDOMINAL MASS
History
Christopher is a 3-year-old boy who presents to the children’s day unit via his GP. The previous evening his mother noticed a lump in his abdomen while drying him after a bath. He has no urinary symptoms and his bowels open normally twice daily. He is otherwise entirely fit and well, and there is no other history of note.
Examination
Christopher is generally healthy with no anaemia, jaundice or lymphadenopathy. His height and weight are on the 75th centile. His blood pressure is 115/75 mmHg. Both heart sounds are normal with no murmurs and his chest is clear. In his abdomen there is a 12-cm-diameter smooth, firm mass in the right flank that extends across the midline. There is no hepatosplenomegaly. The external genitalia are normal.
INVESTIGATIONS
Normal
Haemoglobin 11.7 g/dL 11.5–15.5 g/dL
White cell count 8.4 109/L 5.5–15.5 109/L
Platelets 365 109/L 150–400 109/L
Sodium 139 mmol/L 138–146 mmol/L
Potassium 4.3 mmol/L 3.5–5.0 mmol/L
Urea 2.0 mmol/L 1.8–6.4 mmol/L
Creatinine 45 mol/L 27–62 mol/L
C-reactive protein 6 mg/L 6 mg/L
Midstream urine 10 red cells 1–10 white cells No growth
Abdominal ultrasound – there is an 11 cm, apparently well-capsulated, solid
heterogeneous mass arising from the right kidney. There is no evidence of calcification
Questions • What is the commonest cause of an abdominal mass in childhood? • What is the most likely diagnosis in this case? • Where should he be managed? • What complication has arisent?
Medicine
The commonest cause of an abdominal mass – occasionally huge – in childhood is faeces. It is characteristically craggy, mobile and in the lower abdomen. However, abdominal masses in children should be assumed to be malignant until proven otherwise, and if there is any doubt, imaging with ultrasound is required. In an otherwise healthy asymptomatic child, the most likely diagnosis is a Wilms’ tumour or nephroblastoma, a neoplasm of the kidney comprising approximately 6 per cent of childhood cancers; 7 per cent are bilateral. It is not unusual for these to present after parents have found the mass incidentally. Wilms’ tumours may be associated with hemihypertrophy, aniridia (hypoplastic iris commonly associated with macular and optic nerve hypoplasia) and other congenital abnormalities, usually of the genitourinary tract. Children with Beckwith–Wiedemann syndrome (mutations at 11p15.5, hemihypertrophy, macroglossia and visceromegaly) have such an increased risk of Wilms’ (approximately 4 per cent) that they are screened regularly during early childhood. The main differential diagnosis is neuroblastoma (NB) – an embryonal cancer of the peripheral sympathetic nervous system. Most arise in the abdomen either in an adrenal gland or in the retroperitoneal sympathetic ganglia. The mass usually causes discomfort. Sadly, children with NB often present with symptoms of metastatic spread, such as fever, bone pain, irritability and weight loss – unusual in Wilms’. Tumour markers and imaging help distinguish the two. Ninety-five per cent of NB patients have raised urine vanillylmandelic acid (VMA) and homovanillic acid (HVA). Unlike NB, Wilms’ tumours rarely calcify. Surgery is the mainstay of treatment for Wilms’ tumour with pre- and post-surgery chemotherapy and radiotherapy depending on the stage. The prognosis for Wilms’ is excellent, with stage 1–3 patients having an overall cure rate of 88–98 per cent. Those with stage 4 disease, with distant metastases, have a poorer but still relatively favourable prognosis of about 75 per cent. There is good evidence that prognosis in all childhood cancers improves in children managed by specialist units, although some care can be local on a ‘shared care’ basis. Centralization of care, multidisciplinary teams, entry into randomized controlled trials and the use of national or international protocols have steadily improved the prognosis in all childhood cancers. His BP is high for a child of his age. Children dislike having their BP measured so it can be difficult to measure accurately. There are electronic devices commonly in use but their results should be interpreted with caution and every effort made to measure BP with standard equipment. The cuff width should be at least two-thirds of the distance from the elbow to the shoulder. Normative ranges according to sex, age and height centile exist for children and adolescents. They are presented as percentiles, with the 95th percentile defining hypertension. In Wilms’ tumour, BP is often raised at presentation, probably due to ischaemia. It may persist for several months even after the primary has been removed and may need drug treatment.
KEY POINTS
• Abdominal masses in children are malignant until proven otherwise
. • Wilms’ tumour can be associated with congenital anomalies.
• The care of all children with cancer should be coordinated by specialist centres.
need an explanation for this answer? contact us directly to get an explanation for this answer