SMLE Paediatrics 4 — Questions and Answers
Question 1: A 4-year-old child presents with easy bruising, petechiae, and a platelet count of 15,000/μL. WBC and haemoglobin are normal. Peripheral smear shows large platelets. What is the most likely diagnosis?
- Acute lymphoblastic leukaemia
- Immune thrombocytopenic purpura (ITP) (Correct answer)
- Disseminated intravascular coagulation
- Aplastic anaemia
Correct answer: Immune thrombocytopenic purpura (ITP)
ITP in children typically presents after a viral infection with isolated thrombocytopenia, petechiae, and bruising. WBC and haemoglobin are normal, and peripheral smear shows large platelets indicating increased platelet destruction with compensatory bone marrow production.
Question 2: A premature neonate in the NICU develops feeding intolerance, abdominal distension, bloody stools, and pneumatosis intestinalis on abdominal X-ray. What is the diagnosis?
- Intussusception
- Necrotising enterocolitis (Correct answer)
- Meconium plug syndrome
- Hirschsprung enterocolitis
Correct answer: Necrotising enterocolitis
Necrotising enterocolitis (NEC) is the most common GI emergency in premature neonates. Pneumatosis intestinalis (air within the bowel wall) on X-ray is the pathognomonic radiographic finding. Management includes NPO, antibiotics, and surgery if perforation occurs.
Question 3: A 2-year-old child presents with recurrent respiratory infections, steatorrhoea, and failure to thrive. A sweat chloride test result is 75 mmol/L. What is the diagnosis?
- Primary ciliary dyskinesia
- Cystic fibrosis (Correct answer)
- Coeliac disease
- Immunoglobulin deficiency
Correct answer: Cystic fibrosis
Cystic fibrosis is diagnosed by a sweat chloride concentration ≥60 mmol/L (a result of 75 is diagnostic). The triad of recurrent respiratory infections, malabsorption (steatorrhoea), and failure to thrive is the classic presentation in young children.
Question 4: A 5-year-old child presents with painless rectal bleeding. The blood is dark red and mixed with stool. A Meckel scan (technetium-99m pertechnetate) is positive. What is the diagnosis?
- Juvenile polyp
- Meckel diverticulum (Correct answer)
- Anal fissure
- Inflammatory bowel disease
Correct answer: Meckel diverticulum
Meckel diverticulum is the most common congenital GI anomaly (rule of 2s: 2% of population, 2 feet from ileocaecal valve, 2 inches long). It contains ectopic gastric mucosa that causes painless bleeding detected by technetium-99m pertechnetate scan.
Question 5: A newborn has a heart murmur, a single palmar crease, epicanthal folds, and hypotonia. The karyotype shows trisomy 21. Which cardiac defect is most commonly associated with this condition?
- Ventricular septal defect
- Atrioventricular septal defect (endocardial cushion defect) (Correct answer)
- Tetralogy of Fallot
- Coarctation of the aorta
Correct answer: Atrioventricular septal defect (endocardial cushion defect)
Atrioventricular septal defect (AVSD/endocardial cushion defect) is the cardiac anomaly most commonly associated with Down syndrome (trisomy 21). Up to 40-50% of children with Down syndrome have congenital heart disease, with AVSD being the most frequent.
Question 6: A 6-year-old child presents with morning headaches, vomiting, and ataxia. MRI shows a posterior fossa mass. What is the most common posterior fossa tumour in children?
- Medulloblastoma
- Astrocytoma (pilocytic) (Correct answer)
- Ependymoma
- Craniopharyngioma
Correct answer: Astrocytoma (pilocytic)
While medulloblastoma is common, pilocytic astrocytoma (cerebellar) is actually the most common posterior fossa tumour in children overall. However, considering all posterior fossa tumours, pilocytic astrocytoma and medulloblastoma are both very common, with pilocytic astrocytoma being the most common benign tumour.
SMLE Paediatrics 4
A 4-year-old child presents with easy bruising, petechiae, and a platelet count of 15,000/μL.
WBC and haemoglobin are normal.
Peripheral smear shows large platelets.
What is the most likely diagnosis?