Hypochondroplasia is a fibroblast growth factor receptor 3 (FGFR3)-related skeletal dysplasia with a broad phenotypic spectrum. Although skeletal abnormalities are generally milder in hypochondroplasia than in achondroplasia, recent advances in prenatal imaging and increasing recognition of affected neonates have enabled earlier radiographic diagnosis. Characteristic findings, including iliac hypoplasia and proximal femoral scooping in neonates, and iliac hypoplasia, short femoral necks, and metaphyseal flaring in childhood, provide important diagnostic clues. However, individuals with mild phenotypes may exhibit only subtle skeletal abnormalities, making it difficult to differentiate them from those with constitutional short stature. Therefore, when clinical and radiographic findings suggest hypochondroplasia, confirmation via FGFR3 genetic testing is recommended. This diagnostic guide summarizes key age-specific radiographic features and emphasizes an integrated diagnostic approach for the early recognition and definitive diagnosis of hypochondroplasia.
Hematopoietic stem cell transplantation-associated partial lipodystrophy (HSCT-PL) is a serious complication that develops about a decade after HSCT in childhood cancer survivors. Typically, patients present with a unique combination of lipoatrophy and lipohypertrophy, known as Dunnigan phenotype. Despite low-to-normal BMI, they often develop metabolic dysfunctions, such as insulin resistance, diabetes, hypertriglyceridemia, and fatty liver. This review discusses current hypotheses for pathogenesis of HSCT-PL. Among the proposed theories, radiation-induced damage of adipose progenitor cells in both subcutaneous and visceral adipose tissue appears to be primary, suggesting that HSCT-PL may reflect accelerated senescence. A literature survey revealed that nearly 90% of reported patients were female. Although the underlying cause of this disparity remains unclear, this is consistent with the greater disease severity in females observed in other adipose tissue-related disorders, including familial partial lipodystrophy and lipoedema. Since patients with HSCT-PL develop severe metabolic dysfunction early in life, they will be at a particularly high risk of premature atherosclerosis. Increased risk of mortality and potential predisposition to malignancy were also identified as important concerns. The development of effective therapeutics is urgently needed. Metreleptin may represent one such option, given its readily availability and demonstrated efficacy in some patients.
Vitamin D deficiency (VDD) and rickets are increasing pediatric health concerns, particularly in high-latitude regions. This comprehensive survey in Hokkaido, Japan (2015–2019), reveals that VDD rickets incidence has surged to 25.4 per 100,000 live births. This rate represents a threefold increase over the past 15 years and is approximately eight times higher than the national average of 3.5 per 100,000 reported by Kubota et al. (2018). The study identified important clinical insights: Exclusive breastfeeding was significantly more common among children with rickets than among those without rickets (83.0% vs. 65.2%), although both groups had similarly low serum 25(OH)D levels. Furthermore, patients with rickets demonstrated substantially lower calcium and phosphorus concentrations. Notably, the incidence of rickets has not decreased despite the recent implementation of national insurance coverage for 25(OH)D testing and the commercial availability of infant vitamin D supplements. These findings highlight the need for strengthened public health education, improved access to native vitamin D supplementation, and proactive management of maternal vitamin D status. Overall, the study underscores the importance of re-evaluating pediatric preventive care strategies in high-risk region.
