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Answers on p 107.
A boy aged 4.5 years, born of a third degree consanguineous marriage, presented with short stature, a lump on the left side of the abdomen that had been seen since he was 7 months of age, and noisy breathing on and off for the past two years. There was no history of jaundice, fever, bleeding from any site, blood transfusion, or fractures. The birth history and milestones were normal. His two siblings were normal.
On examination, the child was grossly stunted. The height was 78 cm, weight 10 kg, and the head circumference 48 cm. The height and weight were markedly below the fifth percentile. The upper segment: lower segment ratio was 1.34:1 indicating proportionate short stature. There was marked pallor but no icterus, oedema, petechiae, or significant lymphadenopathy. There was marked frontoparietal bossing, the sutures were wide open, the anterior fontanelle measured 12 × 12 cm and communicated with an open posterior fontanelle. There was bilateral proptosis, a small nose, and a small poorly developed mandible (fig 1). The uvula was long and the palate high arched. The teeth showed marked caries and an irregular arrangement. The hands were small with short and stubby fingers. The feet were small with short and stubby toes.
On abdominal examination, the spleen was enlarged 13 cm below the left costal margin and the liver was palpable 5 cm below the right costal margin, both were firm and non-tender (fig 1). Fundoscopy revealed bilateral papilloedema with no evidence of secondary optic atrophy. The rest of the systemic examination was normal.
Investigations revealed a haemoglobin concentration of 68 g/l and leucocyte count 14.4 × 109/l; differential count was neutrophils 46%, lymphocytes 50%, and monocytes 4%. The platelet count was 77 × 109/l and corrected reticulocyte count was 0.9%. The peripheral smear showed normocytic and normochromic red blood cells and a few target cells. There were no abnormal cells or parasites seen. Osmotic fragility and haemoglobin electrophoresis were normal. Sickling test and Coombs test were negative. Serum calcium concentration was 2.3 mmol/l, serum phosphorus 1.54 mmol/l, and alkaline phosphatase was low: 139 U/l (normal range 210–810 U/l). The child's IQ was 95.
Skeletal survey showed a generalised and uniform increase in bone density (osteosclerosis) with marked obliteration of the medullary canals (fig 2). Radiography of the skull showed open anterior and posterior fontanelles, separated sutures, wormian bones, non-pneumatised frontal sinuses, and a sclerotic skull base (fig 3). The mandibular angle was obtuse. Radiography of the chest showed thick and dense ribs (fig 4) The clavicles were normal. Radiography of the hands showed hypoplasia and narrowing of distal phalanges (fig 2). There was no evidence of fractures.
Computed tomography of the brain was normal. Audiometry revealed normal hearing in both ears. Bone marrow aspiration showed a leucoerythroblastic reaction indicative of bone marrow inva-sion (myelophthisis). The myeloid:erythroid ratio was 2:1 (normal).
(1) What is the diagnosis?
(2) What is the most important differential diagnosis?
(3) What complications can be anticipated in this case?