Isolated lateralized overgrowth: clinical, radiological, and auxological characteristics of a single-site cohort of 76 cases.

INTRODUCTION
Isolated lateralized overgrowth (ILO), formerly referred to as hemihyperplasia/hemihypertrophy, is the overgrowth of one-half of the body to its contralateral in the absence of a recognizable pattern of malformations or genetic syndromes. Our objective was to analyze the growth clinical and radiological characteristics of patients with ILO under follow-up in a tertiary care hospital in Argentina between 1993 and 2020.


POPULATION AND METHODS
Retrospective, observational, single cohort study of patients with ILO.


RESULTS
A total of 76 cases were included; 41 were males. Median years of follow-up: 5.85 (interquartile range [IQR]: 2.60-10.96), maximum: 15.76 years. Forty-eight of 76 patients had overgrowth compromising more than 1 body segment (complex ILO). The mean birth weight Z-score of term girls with complex ILO was +0.51 (standard deviation [SD]: 0.91) (p 0.022). Most children grew between the 50th and 97th centile of the Argentinian population height reference. The median leg length discrepancy was 1.5 cm (IQR: 1.01-2.2) in patients receiving medical treatment and 3.70 cm (IQR: 2.95-3.98 cm) in those who required epiphysiodesis. Progression of discrepancy ≤ 2 cm was observed in 75% of cases. Renal asymmetry ≥ 1 cm was observed in 8 cases; Wilms tumor was noted in 2 cases: mean age at diagnosis: 0.75 years.


CONCLUSIONS
Prenatal growth of children with ILO is normal, except in girls with complex ILO, in whom it tends to be increased. The average height of boys and girls tends to be located in high centiles with normal growth over time. Embryonal tumor screening is recommended in this group of children.