A histopathologic comparison between synchronous and single primary oral squamous cell carcinomas.

Objective: This study compares synchronous oral squamous cell carcinomas (OSCCs) with single primary OSCCs to assess the histopathologic parameters with a known prognostic significance.

Study Design: Twenty-eight cases of synchronous OSCCs and a control group of single primary OSCCs were compared for 15 histologic prognostic variables.

Results: Results showed significantly less amount of abnormal mitoses (synchronous-1: P = .002; synchronous-2: P = .006) and tumor-induced stroma (synchronous-1: P = .011; synchronous-2: P = .001) in synchronous OSCCs than in single primary OSCCs. Depth of invasion was considerably lower in synchronous OSCCs than in single primary OSCCs (synchronous-1: P = .007; synchronous-2: P = .002). Lymph node metastasis (synchronous-1: P = .051; synchronous-2: P = .051) was found to be rare in synchronous OSCCs compared with single primary OSCCs.

Conclusion: Synchronous OSCCs show less aggressive histopathologic features than single primary OSCCs.