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Objective: The aim of this study was to evaluate bcl-2, bax (apoptotic-oncoproteins), and Ki67 (cell proliferation-marker) expression in thymus of patients with myasthenia gravis (MG) and to determine the potential correlation with clinicopathologic parameters., Methods: The study was done on 38 patients (16 males, 22 females; mean age 38+/-10 years) with MG who underwent modified maximal thymectomy (MMT). Clinical staging (Osserman classification) included stage I in three, IIA in 19, IIB in 13 and III in three. Microscopic examination of thymus showed thymic hyperplasia in 19, atrophy in eight, thymoma in nine and thymic carcinoma in two. On paraffin sections, the streptavidin-biotin technique, using antibodies to bcl-2, bax, and Ki67, was employed, and in situ hybridization with digoxigenin-labeled probes to bcl-2 and bax was performed. In addition, the apoptotic body index (ABI) was assessed via the TUNEL method. Staining results were correlated with clinicopathologic parameters., Results: Bcl-2 expression was higher in hyperplasia and thymoma cases, compared to thymic carcinomas (P<0.001). Higher expression in carcinomas, compared to hyperplasia and thymomas, was observed for bax (P<0.001), Ki67 (P<0.001) and ABI (P<0.001). Statistical analysis demonstrated: (A) positive correlation of bax+ cells with MG stage (P<0.001), ABI and %Ki67+ cells with MG stage (P<0.001, respectively), %Ki67+ and %bax+ cells with ABI (P<0.05); and (B) reverse correlation between %bcl-2+ cells and MG stage (P<0.05)., Conclusions: In patients with MG who underwent MMT, bcl-2, bax, and Ki67 expression correlates positively or reversibly with the microscopic findings of thymus. Increased apoptosis and proliferation accompany advanced disease stage and possible worse prognosis.

We studied the intraoperative diagnostic value of imprint cytology in 230 samples obtained from surgical specimens submitted for frozen section diagnosis. A rapid hematoxylin-eosin stain was used. Intraoperative imprint cytology achieved an accuracy rate of 94.3%; for benign lesions the accuracy was 97.5%, and for malignant lesions it was 91%. Overall, the false-negative and suspicious-for-malignancy rates were 1.3% and 4.3%, respectively. No false-positive results were found. The diagnostic yield when intraoperative imprint cytology and frozen section were used together was 99%. It is apparent that imprint cytology is a quick and simple method with wide applicability in the histopathologic diagnosis of lesions from all organs. The value of the method is enhanced when it is used with frozen section diagnosis.