ATYPICAL FEATURES IN SALIVARY-GLAND MIXED TUMORS - THEIR RELATIONSHIPTO MALIGNANT TRANSFORMATION

Although criteria far distinction between the benign and malignant ele ments Ln carcinoma ex mixed tumor have been adequately described, ther e have not been any attempts to identify clinical or histologic featur es in benign mixed tumors that indicate increased risk of malignant ch ange. I;or this reason, 65 mixed tumors of the major and minor salivar y glands that exhibited atypical histologic features were examined in an attempt to analyze which, if any, of these features might indicate a greater likelihood of malignant transformation, The atypical feature s evaluated were hypercellularity, capsule violation, hyalinization,ne crosis, and cellular anaplasia The mitotic rate was also analyzed. The age of the patient, and the site, size, and prediagnostic duration of the tumor were recorded and, together with the histologic findings, w ere correlated with follow-up information. Nine (13.8%) of the 65 tumo rs underwent malignant transformation. Five of these patients died of the tumor, two others had distant metastases and were alive with the d isease, and two were free of disease. Benign mixed tumors lat showed p rominent zones of hyalinization or at least moderate mitotic activity were more likely to develop carcinoma than those that did not. chi(2) analysis indicated that only hyalinization was significant (P < 0.05), but, with Fisher's exact test (two-tailed), this and;all of the other features evaluated revealed a P value greater than 0.05. The other at ypical features faded to correlate with malignant change. Clinical fin dings at the initial diagnosis that indicated a greater likelihood of malignant transformation were occurrence in the submandibular gland, o lder patient age, and large tumor size.