CT determination of lymphocytic infiltration around head and neck squamous cell carcinomas may be a predictor of lymph node metastases

The histological detection of a peritumoral lymphocytic infiltration (PLI) and a sharp tumor border in patients with squamous cell carcinoma (SCC) of the larynx, pharynx or oral cavity is inversely correlated with the development of cervical lymph node metastases and is therefore a favorable prognostic factor. However, preoperative biopsies are often too small for an evaluation of these tumor features. Here, we examined retrospectively whether elevation of peritumoral density values as determined by contrast-enhanced computed tomography (CT) correlates with PLI and the presence of cervical lymph node metastases. A total of 40 patients with primarily resected SCC were studied (pT1=8, pT2=13, pT3=9, pT4= 10); 25 patients were pN-positive. All tumors were histologically analyzed regarding PLI (present or not) and the tumor border (sharp or infiltrating). Based on standardized CT examinations (90 ml contrast agent at 1.5ml/s), repeated region-of-interest (ROI)-based peritumoral density measurements were obtained. Correlations between CT density, PLI, tumor border and metastatic involvement of regional lymph nodes were statistically evaluated. CT densities were significantly higher (P<0.001) in patients with PLI and sharp tumor borders than in patients without PLI and patients with infiltrating tumor borders. Moreover, the presence of PLI, sharp tumor borders and elevated peritumoral CT densities were each correlated with the absence of lymph node metastases (P<0.001). An elevation of peritumoral CT densities is linked to PLI and sharp tumor borders on histology and a lower risk to develop lymph node metastases. For a patient-adapted therapy, these relations have to be prospectively evaluated regarding their prognostic relevance.