A Weak Infant with Large Muscles: What's Your Diagnosis?

Asthenia and developmental delay seem at odds with well-defined musculature in this 9-month-old. What Dx do you suspect?

A 9-month-old boy is seen for a well-child visit. He is new to the practice and presentation is complex; the mother complains of asthenia and delayed development in this infant with apparent muscular hypertrophy.  Follow Dr John Schneider and his virtual resident and nurse practitioner through history and physical exam; look at the images from the visit. Can you make the diagnosis?   ResourcesShaw C, Shaw P. Kocher-Debre-Semelaigne syndrome: hypothyroid muscular pseudohypertrophy-a rare report of two cases. Case Rep Endocrinol. 2012;2012:153143. doi: 10.1155/2012/153143. Epub 2012 Mar 12.  http://www.ncbi.nlm.nih.gov/pubmed/?term=10.1155%2F2012%2F153143Sindoni A, Rodolico C, Pappalardo MA, Portaro S, Benvenga S. Hypothyroid myopathy: A peculiar clinical presentation of thyroid failure. Review of the literature. Rev Endocr Metab Disord. 2016 May 7. [Epub ahead of print] http://www.ncbi.nlm.nih.gov/pubmed/27154040Mishra D, Juneja M. Kocher-Debre-Semelaigne syndrome.  J Pediatr Neurosci. 2014;9:289-90. doi: 10.4103/1817-1745.147570. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4302559/Tewari VV, Mehta R, Tewari K. Kocher-Debre-Semelaigne syndrome: response to thyroxine replacement therapy. Internat J Clin Endocrin Metab. 2016:2:5-7. Published on 10 June, 2016 http://www.peertechz.com/Clinical-Endocrinology-Metabolism/ [see first article]