Nutritional rickets masquerading as spinal muscular atrophy type III.

Muscle atrophy, weakness, and loss of ambulation in the pediatric population are signs of progressive neuromuscular diseases. Rapid identification of such diseases is important to prevent further progression. In pediatric neurology, it is well understood to include neuromuscular disorders in the differential for such presentations. We report a case of severe nutritional rickets that mimicked the presentation of spinal muscular atrophy type III and discuss the importance of including rickets in the differential for muscle atrophy and loss of ambulation. A 33-month-old African American boy with several months of gait abnormality was referred to outpatient neurology. The initial diagnostic evaluation focused primarily on neuromuscular disorders, specifically SMA type III, given the absence of reflexes on examination and the history of prior ambulation. After an unfruitful genetic workup, it was elucidated that the child had very poor dietary intake and minimal sun exposure causing nutritional rickets that improved with intervention.