Human Papillomavirus-11-associated Recurrent Respiratory Papillomatosis Is More Aggressive Than Human Papillomavirus-6-associated Disease R. RABAH, 1 * W.D. LANCASTER, 2,3 R. THOMAS, 4 AND L. GREGOIRE 5 1 Department of Pathology, Children’s Hospital of Michigan, 3901 Beaubien Boulevard, Detroit, MI 48201, USA 2 Department of Obstetrics and Gynecology, Wayne State University, Room 3248 Scott Hall, 540 East Canfield Avenue, Detroit, MI 48201, USA 3 Center for Molecular Medicine and Genetics, Wayne State University, Room 3248 Scott Hall, 540 East Canfield Avenue, Detroit, MI 48201, USA 4 Children’s Research Center of Michigan, 3901 Beaubien Boulevard, Detroit, MI 48201, USA 5 Department of Immunology and Microbiology, Wayne State University, Room 3248 Scott Hall, 540 East Canfield Avenue, Detroit, MI 48201, USA Received June 23, 1999; accepted November 5, 1999. ABSTRACT The aim of this study was to determine whether viral type (HPV-6 vs. HPV-11) could predict the clinical course of recurrent respiratory papillomatosis in chil- dren. Viral typing, using the polymerase chain reac- tion, was performed on laryngeal biopsies of 61 pa- tients treated at Children’s Hospital of Michigan. HPV-6 was detected in 29 of the patients’ biopsies and HPV-11 in 32 biopsies. HPV-11 was more common among the African-American patients than among Caucasians (P 5 0.001). Patients with HPV-11 were diagnosed at a younger age (36.2 vs. 48.2 months; P 5 0.04) and were more likely to have active disease (P 5 0.0311) at the time of this study. They tended to have longer periods of disease activity (8 years vs. 5 years; P 5 0.026), required more surgical procedures (42 procedures/patient vs. 13.6; P 5 0.02), and more pro- cedures per patient, per year (2.9 vs. 5.3; P 5 0.0164). Three of the patients infected with HPV-11 developed invasive papillomatosis and bronchogenic squamous cell carcinoma, and two of these patients died of dis- ease. Our findings suggest that HPV-11 infection con- fers a more aggressive course to recurrent respiratory papillomatosis. Key words: HPV, human papillomavirus, recurrent re- spiratory papillomatosis INTRODUCTION Recurrent respiratory papillomatosis (RRP) in chil- dren is caused by infection with human papilloma- virus (HPV) [1]. HPV types 6 and 11 are the most frequently detected genotypes in RRP of the more than 70 genotypes known to date. The course of disease may vary considerably from patient to pa- tient [2]. Some patients have few recurrences and experience spontaneous remission. Other patients have frequent recurrences into adulthood with the need for repeated excisions of their lesions to relieve symptoms. A small number of patients develop a disseminated form of the disease with pulmonary involvement, and a few develop laryngeal or bron- chogenic carcinoma. Factors that may explain the variation in disease outcomes are multiple. These could include genetic predisposition, immune status, *Corresponding author Pediatric and Developmental Pathology 4, 68 –72, 2001 DOI: 10.1007/s100240010105 Pediatric and Developmental Pathology © 2001 Society for Pediatric Pathology