Which physical findings are characteristic of endocrine disorders in McCune-Albright syndrome (MAS)?

Updated: Jan 17, 2019
  • Author: Gabriel I Uwaifo, MD; Chief Editor: George T Griffing, MD  more...
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Answer

Hyperthyroidism is uncommon in MAS, commonly appearing as a hypermetabolic state. Findings may include tachycardia, supraventricular arrhythmias, hypertension, hyperthermia, tremor, sleeplessness, and involuntary weight loss. Infants with hyperthyroidism often exhibit failure to thrive. Hyperthyroidism does not always occur in infancy: There are case reports describing hyperthyroidism occurring abruptly in later childhood, including 1 report of thyroid storm after surgery for FD.

Cushing syndrome is also rare in MAS. Patients with Cushing syndrome have profound growth failure in infancy. Although both weight and length percentiles decrease, linear growth failure is more pronounced. Frequently, these infants have round cushingoid faces and may have markedly decreased muscle tone and soft doughy skin. Hypertension also may be present.

GH-producing somatotroph adenomas can occur in McCune-Albright syndrome. In children, GH excess results in a marked increase in linear growth velocity. If it goes untreated, features of acromegaly can develop later in life, including enlargement of the hands and feet and coarsening of the facial features. Individuals with GH excess may also have hypertension and mild decreases in muscle tone.

Rarely, severe hypophosphatemia can occur in MAS. If it is not treated, severe rickets and short stature can result. Typical findings in hypophosphatemic rickets include bowing of legs, widening of wrists, and thickening of the costochondral junction (rachitic rosary).

Infants with MAS may have persistent jaundice and mild hepatomegaly but generally lack other manifestation of liver failure.


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