Imaging Appearances of Musculoskeletal Developmental Variants in the Pediatric Population

Variations in musculoskeletal development in children are commonly encountered. These variants often have a confusing appearance on imaging and may simulate pathologic conditions. However, in many instances, these normal variants have certain features that allow for confident determination of the benign nature of these entities. An awareness of the characteristic imaging features is therefore important for radiologists. In this review, we focus on 4 specific categories of variants in the development: (1) variations in the normal ossification of skeletal structures, (2) the appearance of tendinous and ligamentous insertions in the developing skeleton, (3) overlapping lines that can be confused with fractures or other pathologic conditions, and (4) variant orientation of normal bones. We review the etiology and imaging appearance of these entities and also describe methods of differentiating these benign entities from pathologic lesions. Although in certain cases, correlation with clinical parameters is needed to confidently diagnose the lesion as benign, in many cases, an appreciation of the characteristic imaging features alone would suffice and prevent a potentially costly workup.