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

First patient is a 9-month-old boy, in for well-baby visit and new to the practice. You note widespread muscular hypertrophy but mother describes very significant developmental delays,

Significant PMH:

Born at 43 weeks; prolonged jaundice requiring phototherapy; delayed defecation; noted to be "floppy" post-delivery but was discharged.

Note overdeveloped masseter muscles. Cry is hoarse and weak.

Mother says suck is weak, despite larger masseter muscles. Note large, broad tongue.

Muscles are overdeveloped--how could he be described as a floppy baby?

Calf muscles are also very well defined. You note that extremities are somewhat edematous and that the skin is dry.

Significant umbilical hernia.

Review of details: Postmature; delayed defecation/constipation; prolonged jaundice; hypotonic muscles; umbilical hernia; open fontanels/delayed closure; large tongue

Presumptive diagnosis?

A. Congenital muscular dystrophy. B. Mucopolysaccharidoses. C. Glycogen storage disease D. Hypothyroidism

Diagnosis: Kocher-Debre-Semelaigne Syndrome

Rare presentation of neonatal hypothyroidism in which there is a diffuse myopathy and pseudohypertrophy.

Helpful mnemonic on next slide. Good to remember -- may show up on a board exam.

Hypotonia--Yellow Pallor--Open fontanel--Tongue enlargement--Hernia (umbilical)--Y chromosome-- Rough skin--Oedema--Inactive defecation--Duration (postmature)

If 3 or more of the previous are present, order a T4 level.

Outcome:

Labs indicated low T3, low T4, elevated TSH. Thyroid replacement therapy initiated. Over 6-8 months the muscular pseudo-hypertrophy resolved. Child remained developmentally delayed…the result of a delayed diagnosis.