Knuckle, Knuckle, Dimple, Dimple: Do Not Miss A Diagnostic Opportunity

Turner syndrome (TS) often presents with subtle or overlooked clinical signs, contributing to frequent diagnostic delays. We describe the case of a 13-year-old girl referred for short stature whose only remarkable physical findings were the absence of the fourth and fifth knuckles on both hands-known as Archibald's metacarpal sign-and a short fourth metatarsal. Growth had decelerated after spontaneous menarche, and previous examinations had not recognized these skeletal clues. Radiographs confirmed short fourth and fifth metacarpals. Karyotype analysis identified a complete deletion of the short arm of one X chromosome (Xp), consistent with TS. Further evaluation revealed a bicuspid aortic valve, autoimmune thyroiditis with subclinical hypothyroidism, and reduced ovarian reserve. Archibald's sign, caused by SHOX haploinsufficiency, is present in about one-third of individuals with TS but may also appear in other disorders or even healthy individuals. This case highlights the diagnostic value of careful physical examination in girls with short stature. Recognizing seemingly minor skeletal findings can prompt timely karyotyping, allowing earlier detection of TS and appropriate long-term management.