Child with prolonged leg pain and bruising.

A 12-year-old boy was admitted to the paediatric ward with a 4-month history of worsening pain and bruising to his legs, which had resulted in a progressive reduction in his mobility. He initially had had difficulty weight bearing, which had then progressed further making him wheelchair bound. On examination, there was extensive bruising (figure 1) to his oedematous legs, worse on his right leg compared with his left. His background of autism and 15q13.3 deletion, along with maternal learning difficulties, made deciphering a clear history difficult. However, there was no account of trauma, and he had been afebrile throughout his illness. He had though lost 6 kg in weight but remained clinically stable. He was admitted to the ward for further assessment.edpract;archdischild-2019-318124v1/F1F1F1Figure 1Clinical photograph showing bilateral bruises and swellings of the legs. QUESTION 1: What differentials should be considered? QUESTION 2: What investigation is more likely to suggest the diagnosis?Baseline bloods: full blood count-including platelets, albumin and coagulation.Extended bloods: vasculitis screen, erythrocyte Sedimentation Rate, endocrinopathies and iron studies.Doppler ultrasound calves.X-ray legs/hips.MRI tibia and fibula.Initial investigations showed a haemoglobin of 67 g/L, with mean cell volume of 76 fL. Platelet count and white cell counts, including differentials, were all within range. Infection markers, renal function tests, liver function tests and clotting screens were all normal. Leg X-rays were performed and showed no obvious fracture. However, there were some bone changes noted that had not been present 4 months prior during a previous presentation.USS Doppler of his calves were done, excluding deep vein thrombosis.Further investigations as to possible causes of his anaemia and other symptoms were then started, including rheumatology screens, haemaglobinpathy screens, endocrinopathies and viral screens. These results, along with vitamin D levels and bone profile, all came back normal. However, iron studies showed low serum iron and transferrin saturation. He had been empirically treated with a course of intravenous ceftriaxone on admission, which was subsequently stopped in view of lack of any evidence (clinically, radiologically or otherwise) of osteomyelitis, septic arthritis or other infective state.His behaviour on the ward, however, quickly raised some questions; in particular his detailed dietary history showed a very limited range, consisting solely of chicken nuggets, chips and pizza.Therefore, while awaiting results of any definite 'cause' of his immobility, his care was managed holistically. He was started on oral iron therapy and a strict dietary plan, including Ensure supplements. Physiotherapy was started, and various methods to encourage him to mobilise were commenced. His reluctance to engage with these 'treatments' initially caused problems, however through negotiation of 'iPad time' with compliance, they were slowly built up. Along with other professionals, the safeguarding team were also involved in his care at this point.Though a clear diagnosis was still unclear, he clinically improved. Oedema of his legs and bruising reduced, and he was able to mobilise a few steps further each day on the ward. QUESTION 3: What is the most likely action that would help confirm the diagnosis?Bone marrow biopsy.Full-body MRI.Complete nutritional history.Referral to tertiary orthopaedic centre.Answers can be found on page 02.