Microinvasive oral squamous cell carcinoma- A clinicopathological study

Abstract

Background and objectives: Microinvasive oral squamous cell carcinoma is an early stage malignancy characterized by invasion of superficial lamina propria without invasion of deeper structures. These lesions have a varied clinical presentation, minimal lymphatic involvement and a better prognosis. However, there is no clear consensus on its diagnosis and subsequent management. The aim of this study is to assess the depth of invasion of confirmed cases of microinvasive oral squamous cell carcinoma using special stains and immunohistochemistry with clinical correlation of these lesions. Method: Tissue specimen of clinically diagnosed cases of oral leukoplakia (n=90), oral submucous fibrosis (n=60) and oral carcinoma (n=50) were microscopically evaluated for the presence of microinvasion by two independent examiners. The next step involved confirming the basement membrane breach by using Periodic acid Schiff (PAS) stain for evaluating the integrity of basement membrane. The confirmed cases were assessed using special stain and immunohistochemistry to measure the depth of invasion and were further correlated with the clinical features. Results: A total of 29 cases were confirmed as microinvasive OSCC. These included clinically diagnosed 11 cases of leukoplakia, 7 cases of OSMF and 11 cases of carcinoma. Median age at diagnosis was 46 yrs; males (69%) were more affected than females (31%). The predominant risk factor was tobacco chewing alone (31.03%) which was in the form of gutkha and arecanut; common site was buccal mucosa (76%); predominant clinical presentation was a patch; and histopathology revealed varying grades of epithelial dysplasia. The mean depth of invasion was 31.29 µm (0.03 mm) with the range being 16.91-66.6 µm (0.02-0.07 mm). Conclusion: The study suggest that depth of invasion could be a reliable marker to assess microinvasion and that severity of epithelial dysplasia is not a prerequisite for microinvasive carcinoma.