Reactive localised inflammatory hyperplasia of the oral mucosa.

OBJECTIVE To document the histopathological pattern and distribution of reactive localised inflammatory hyperplastic lesions of the oral mucosa diagnosed at the University of Nairobi Dental Hospital over a 14 year period. DESIGN A retrospective, cross-sectional descriptive study. SETTING Division of Oral Pathology and Oral Medicine, histopathology laboratory, School of Dental Sciences, University of Nairobi. SUBJECTS A total of 3135 oral biopsies were accessioned in the oral diagnostic histopathological Laboratory registry over a period of 14 years from March 1991 to December 2005. RESULTS Three hundred and thirty three cases were histopathologically diagnosed as reactive inflammatory hyperplasias of the oral mucosa. This constituted 10.6% of the total oral biopsy specimens analysed during this period. Fibrous epulis was the most common histological sub-type with 129 cases (38.7%) followed by pyogenic granuloma with 94 (28.3%) cases. Six (1.8%) cases were peripheral giant cell granuloma and three cases (0.9%) were those of denture irritation hyperplasia. The age distribution ranged from 2 to 78 years (mean = 30.5 years) with a peak at 20-29 years. Gender distribution showed that 107 (32%) cases occurred in males and 226 (68%) cases females. Similar trends were observed in most of the histological sub-types. Fibrous epulis occurred in 41 male (31.8%) cases and in 88 (68.2%) females with an age range of 2 to 78 years (mean = 30.5 years). As for the pyogenic granuloma, 26 (27.7%) lesions occurred in males and 68 (72.3%) in females with an age range of 2 to 75 years (mean = 30.1 years). Among all the histopathological sub-types it was shown that 223 (67.0%) cases were fibrous, 104 (31.2%) vascular and six (1.8%) peripheral giant cell granuloma. Gingival lesions were the most common with 257 (77.2%) cases followed by 28 (8.4%) in the tongue, 16 (4.8%) lips, 15 (4.5%) cheek, six (1.8%) palate and the rest on the floor of the mouth and other mucosal sites. The duration of these lesions was recorded in 182 (54.7%) cases and ranged from 1 week to 16 years (mean = 1.8 years). Only 15 (4.5%) cases were reported to have recurred and all of them were gingival lesions. CONCLUSION The present study has shown that the prevalence of reactive localised inflammatory hyperplasia (RLIHs) of the oral mucosa was 10.6% with fibrous epulis and pyogenic granuloma having been the most common histopathological sub-types predominantly affecting females. Although RLIHs are distinguished on clinical or histopatholocal grounds, it is important to appreciate that they are variations of the same basic process.