Correlation of histology, human papillomavirus, and viral load in laryngeal papillomas of childhood

The purpose of this study was to analyze 47 laryngeal papillomas in children for human papillomavirus (HPV) DNA by in situ hybridization and RT in situ PCR and to correlate these results with the histologic findings. HPV DNA was detected by in situ hybridization in 29 of 47 (62%) of the cases; all positive cases contained HPVs 6 or 11. HPV DNA detection was associated with a statistically significant increase in the presence of keratobyaline granules, nonuniform perinuclear halos, and marked papillomatosis (P < 0.02). The viral load was low, defined by less than 20 HPV-positive cells per tissue with a correspondingly weak signal, in 19 of 29 (65%) of the positive cases. In comparison, a high viral load was evident in 19 of 21 (90%) of vulvar condylomas. The laryngeal lesions negative for HPV by in situ hybridization were tested for HPV by RT in situ PCR using primers specific for HPVs 6 and 11. The detection rate of HPV increased to 38 of 47 (81%) after PCR amplification. It is concluded that laryngeal papillomas in childhood are characterized, in general, by a relatively low HPV viral load and that the cases with productive viral infection, as demonstrated by in situ hybridization, are associated with nonuniform keratohyaline granules, nonuniform perinuclear halos, and marked papillomatosis.