Epidemiologic study of Langerhans cell histiocytosis in children.

OBJECTIVE: The etiology and pathogenesis of Langerhans cell histiocytosis (LCH) remain poorly understood. We conducted an exploratory epidemiologic study to investigate potential risk factors associated with LCH. STUDY DESIGN: We used a case-control study design to obtain data from parents of children with LCH (n = 459) who were members of the Histiocytosis Association of America and Canada. The two control groups consisted of 683 community control subjects and 3719 children with childhood cancers treated at participating Children's Cancer Group institutions. RESULTS: The median age at diagnosis of LCH was 1.8 years (range 0.1 to 14.6 years). Cases were categorized as multisystem LCH (MS-LCH) (n = 208) and single-system LCH (SS-LCH) (n = 198). Statistically significant associations included the following: infections in the neonatal period (MS-LCH, odds ratio (OR) = 2.2), solvent exposure (SS-LCH, OR = 54.9), childhood vaccinations (MS-LCH and SS-LCH, OR = 0.4), thyroid disease in the proband (MS-LCH and SS-LCH, OR = 21.6), and family history of thyroid disease (MS-LCH and SS-LCH, OR = 1.4). The association with thyroid disease in the proband was explained partially by the involvement of the pituitary, with the relative risk decreasing when patients with diabetes insipidus and thyroid involvement were excluded from analysis. CONCLUSIONS: This large hypothesis-generating study provides directions for future investigations in well-designed population-based or hospital-based epidemiologic studies.

A study of nasal respiratory resistance and craniofacial dimensions in white and West Indian black children.

Two studies have shown that there are morphologic differences in the nasopharynx between the major racial groups. This investigation was conducted to see whether these morphologic differences affected nasal respiration. Twenty-two West Indian and 24 white children (mean age of 13 years 11 months) were studied to examine the relationship between nasorespiratory function and nasopharyngeal and dentofacial structure. The nasorespiratory function was measured in terms of nasal respiratory resistance, NRR, (Pascals/cm3 per second), both by anterior and posterior methods, with a computerized rhinomanometer. Nasopharyngeal structure was described in terms of cephalometric variables. The West Indian cephalometric profile generally conformed to its existing description in the literature including prognathic jaws and bimaxillary proclination; in addition, the West Indians were found to have a greater bony nasopharyngeal width (posterior nasal spine-basion) and shallower nasopharyngeal roof angle (posterior nasal spine-hormion-basion). All rhinomanometric measurements were significantly lower in the West Indian group, especially when posterior rhinomanometry was used. The correlation coefficients between the cephalometric and the rhinomanometric measurements were statistically significant but low. In addition, the measure of mandibular prognathism (angle SNB) was also found to be significantly correlated with the nasorespiratory resistance.