Pectus Excavatum (PE), Pectus Carinatum (PC), Poland Syndrome (PS), Sunken Chest Deformity (SCD), Barrel Chest Deformity (BCD), Body Builder Deformity (BBD), and Long Upper Chest Wall (LCW) are Chest Wall Deformities (CWDs) that are documented in the medical literature. A scoliotic CWD, unlike PE or PC, does not only concern the anterior chest wall but is an expression of thoracic torsion due to the scoliotic torsion of the spine and adjacent ribs.

Regular use of Angle of Trunk Rotation (ATR) measurements for scoliosis screening and also for clinical follow-up of our scoliosis patients under treatment. In some patients, when ATR measurements exceed the screening threshold but without a significant degree of curvature on the X-ray (Cobb angle), a Hemidystrophic Thorax (HDT) is diagnosed. The purpose of this paper was to present a case series of patients with this kind of thoracic deformity because this may be mimicking scoliosis to a significant degree.

Thoracic scoliosis

Typically, we find a rib hump dorsally on the convex side of the curvature when the thoracic spine is affected and a lumbar hump dorsally on the convex side of a lumbar curve when the lumbar spine is affected. When thoracic scoliosis is analysed more closely using a 3D scan of the trunk, we typically find a rotation of the trunk backward on the rib hump side and a rotation forward on the thoracic concave side.

A new form of CWD has been found by the first author: As has been shown in this case series, a Hemidystrophic Thorax (HDT) was found in patients with slight scoliosis and in cases without scoliosis (Cobb angle of 10° or less). The condition of HDT may lead to significant rib humps, which mimic scoliosis. 

The condition of HDT may lead to significant rib humps that mimic scoliosis. According to our case series, mild scoliosis can also be associated with HDT. HDT, according to the cases presented in this study, seems to be a relatively benign deformity. Long-term observations are necessary before a final conclusion can be drawn with respect to prognosis.