A Novel Frameshift Homozygous Mutation in DHCR7 with a Known Missense Homozygous Mutation in the PROC in a 6-Year-Old Boy: A Child with Two Rare Genetic Diseases.

Background  Ulnar styloid impaction syndrome (USIS) is produced by the tip of an oversized ulnar styloid inappropriately contacting the triquetrum. This condition results in chondromalacia, synovitis, and ulnar-sided wrist pain. Case Description  We report a rare case of bilateral USIS that presented with a prolonged course. The patient's symptoms resolved in both wrists following two separate ulnar styloidectomy procedures. Literature Review  Our case differs from previous reports in that it involves a patient whose own history of USIS led to a timelier diagnosis of the same disease in the contralateral wrist. To the best of our knowledge, there are no prior reports of bilateral USIS. Clinical Relevance  USIS remains an uncommon cause of ulnar-sided wrist pain and a particularly difficult diagnosis to confirm. Here, we illustrate that this syndrome can be confidently approached using a combination of careful attention to patient history, physical examination, and various imaging methods.