A 4-year-old boy presented with delay in developmental milestones and aggressive behaviour. An axial CT scan of the brain was done (Figure 1).

Subsequent evaluation revealed normal serum calcium and inorganic phosphorus values with an elevated serum alkaline phosphatase. His arterial blood gas analysis was suggestive of metabolic acidosis with anionic gap of minus 15.1.

His skeletal X-rays were done (Figures 2 and 3).

Author information: Suresh Prabhu, Senior Registrar; Jubbin J Jacob, Senior Registrar; Nihal Thomas, Consultant; Department of Endocrinology, Christian Medical College and Hospital, Vellore, Tamil Nadu, India

Correspondence: Jubbin Jagan Jacob, Senior Registrar, Department of Endocrinology, Christian Medical College, Vellore, Tamil Nadu, India 632004. Fax: +91 461 5203570; email: jubbin@india.com