Peritumoral bone change in oral squamous cell carcinoma: Correlation of imaging features with histopathological findings

Abstract

Purpose When oral squamous cell carcinoma (OSCC) invades the jaw bone, increased attenuation on computed tomography (CT) or pathologic signal intensity (SI) on magnetic resonance (MR) images is frequently observed in the remaining margin, which makes it difficult to determine the extent of tumor invasion. The aims of the current study were, in OSCC patients with mandibular bone invasion 1) to assess the prevalence of underlying bone change on preoperative CT and MR images, 2) to investigate the relationship between underlying bone change and tumor aggressiveness, and 3) to analyze the area of underlying bone change on histopathology slides through radiologic-histopathologic correlation.

Materials and Methods This study consisted of 137 subjects who underwent mandibulectomy to treat OSCC between September 2009 and December 2016. Preoperative CT and MR images were evaluated by two oral and maxillofacial radiologists to assess the prevalence of underlying bone change. In addition, correlations of underlying bone change with each of radiologic findings (type of bone invasion, depth of bone invasion, tumor size), histopathologic findings (TN stage, degree of malignant cell differentiation), and clinical finding (recurrence) were analyzed. In 18 subjects who underwent mandibulectomy after January 2016, serial section slides of resected specimens were prepared and a blinded oral pathologist analyzed the underlying bone change area on histopathology slides. Histopathologic features (presence of malignant tumor cell, alteration of trabecular bone, fibrosis of marrow space, inflammatory cell infiltration) were evaluated and pattern of peritumoral bone change was classified based on these. Results In preoperative imaging analysis, 69.6% CT and 90.9% MR showed underlying bone sclerosis and pathologic SI in underlying bone marrow. Those with underlying bone change had a significantly aggressive invasion type, deeper invasion depth, and bigger tumor size. Histopathologic pattern of peritumoral bone change was grouped into three patterns: four cases of sclerosis dominant, ten cases of fibrosis dominant, and four cases of invasion dominant patterns. In the cases classified as sclerosis dominant and fibrosis dominant patterns, no malignant tumor cell infiltration was found on histopathology slides while underlying bone changes were observed on preoperative images.

Conclusion Underlying bone change is often accompanied by OSCC in forms of sclerosis or pathologic SI of bone marrow. It is very important to distinguish and differentiate between bone invasion by OSCC and resultant surrounding bone change. This will help to determine the bone margin of surgical resection in patients with OSCC.