LEIOMYOMA OF THE ORAL CAVITY - A LIGHT-MICROSCOPIC AND IMMUNOHISTOCHEMICAL STUDY WITH REVIEW OF THE LITERATURE FROM 1884 TO 1992

Leiomyoma is the most common benign neoplasm in the uterus and stomach but is rare in the oral cavity. There were only 5 oral cases in a ser ies of 7748 leiomyomas of all sites. Benign smooth muscle neoplasms ar e classified into leiomyoma (solid leiomyoma), angiomyoma (vascular le iomyoma) and epithelioid leiomyoma (leiomyoblastoma). 6 cases diagnose d as leiomyoma were retrieved from the files of two oral biopsy servic es over the past 25 years. A light microscopic study including trichro me and phosphotungstic acid haematoxylin (PTAH) stains, and an immunoh istochemical study with the following markers: desmin, muscle specific actin, myoglobin, vimentin, S-100 protein, neuron-specific enolase, f actor VIII and Ulex europeus were done with suitable controls. The hae matoxylin and eosin and Masson's trichrome stains supported a diagnosi s of leiomyoma in all 6 cases but PTAH was positive in only 3 of them. The immunohistochemical study confirmed the diagnosis of leiomyoma in 3 cases. The other 3 were identified as granular cell tumour, myofibr oma and neurofibroma, respectively. The review of the literature contr ibuted the following data: mean age was 41 and median age 39 in 134/14 2 patients. A male sex prevalence 72/137 patients (54.0%) was noted. T he lips were the most common site with 39 cases (27.46%) followed by t he tongue 26 (18.30%), cheeks and palate 22 (15.49%), gingiva 12 (8.45 %), and mandible 8 (5.63%). Prognosis of oral leiomyomas is excellent. Immunohistochemistry is a precise and reliable method for definitive diagnosis of oral leiomyoma.