Neither Carinatum nor Excavatum: Insights Regarding the Novel Postprematurity Thoracic Dysplasia and Traditional Harrison Grooves

Background/purpose: In recent years, a new chest wall malformation (CWM), the postprematurity thoracic dysplasia (PPTD), was reported. It was characterized as an inward deviation of the anterior tips of the 6th ribs and a personal history of prematurity and respiratory distress. At the moment, PPTD's prevalence and etiology are yet to be defined. Thus, we aimed to explore and identify patients with a compatible morphology within a large cohort of patients with CWM. Methods: Retrospective analysis of electronic health records including medical photographs of 4640 consecutive patients with chest wall malformations at our Pectus Clinic between 2002 and 2023. Patients presenting with bilateral inward curvature of the 6th to 8th ribs were included. Among the variables analyzed, the history of preterm birth and ventilatory support requirement were evaluated. Results: From 2069 patients with non-excavated deformities, 29 (1.4%) patients presented a PPTD morphology. After excluding 12 for incomplete records, we found that 9 patients (52.9%) had a positive history of prematurity (group PT) and 8 (47.1%) didn't (group T). However, both groups showed a high incidence of respiratory comorbidities (PT: 89% vs. T: 76%, p = 0.91). The median age of deformity onset was 12 months (IQR 2; 12) and 24 months (IQR 1; 60) for the PT and T groups, respectively (p = 0.37). Both groups showed a low incidence of family history of CWM (PT: 38% and T: 14%, p = 0.57). Conclusions: In this retrospective study including 4640 patients with chest wall malformations, the presence of a phenotype described as postprematurity thoracic dysplasia was similarly distributed among patients with or without a history of prematurity. We hypothesize that this condition, different from pectus excavatum and carinatum, might correspond to the Harrison grooves, a deformity whose etiology was profusely discussed in the medical literature from the first half of the 20th century. Type of study: Comparative retrospective study. Level of evidence: III.