Purpose or Case Report: Trichorhinophalangeal syndrome type I (TRPS I) is a rare autosomal dominant skeletal dysplasia characterized by distinctive craniofacial (pear-shaped nose, long philtrum, thin upper lip, prominent ears, sparse, slow-growing hair, and dystrophic nails) and skeletal abnormalities (short stature, brachydactyly, cone-shaped epiphyses, and hip dysplasia). When bilateral Legg-Calvé-Perthes disease (LCPD) occurs, the femoral head changes typically manifest symmetrically and simultaneously, often suggesting an underlying skeletal dysplasia. We present an unusual case of an 11-year-old male with bilateral asymmetric “Perthes disease,” with the left hip in the late or healing phase and the right hip in the early phase. The patient had no prior history or treatment for left-sided LCPD. He underwent right hip core decompression before genetic consultation. On physical examination, he exhibited relatively sparse hair, short stature, a pear-shaped nose with underdeveloped alae, and shortened digits. Recognition of these characteristic craniofacial features prompted the geneticist to order a skeletal survey and TRPS1 panel. Skeletal survey demonstrated bilateral symmetric cone-shaped epiphyses in the proximal phalanges of both feet and the middle and distal phalanges of the hands, coxa magna and breva of the left hip, and flattening and sclerosis of the right proximal femoral epiphysis. Additional findings included tonguing of multiple thoracic vertebrae, short pedicles of the lower lumbar spine, and decreased interpedicular distance at L5. Differential diagnoses include TRPS, pseudoachondroplasia, multiple epiphyseal dysplasia, or spondyloepiphyseal dysplasia. Molecular testing identified a heterozygous pathogenic variant in TRPS1 (c.1630C>T, p.Arg544*), confirming the diagnosis of TRPS I. This case illustrates that temporally asymmetric, bilateral Perthes-like changes may obscure an underlying skeletal dysplasia and the importance of recognizing characteristic craniofacial features to guide timely genetic evaluation and management.
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