[Distribution of thymic tissue in the mediastinal adipose tissue removed at the thymectomy in 47 patients with myasthenia gravis].

In this report, the distribution of thymic tissue in the mediastinal adipose tissue was examined histologically in 54 patients with myasthenia gravis underwent extended thymectomy. In fourty-seven of 54 patients, the mediastinal adipose tissues were removed from 6 different parts adjacent to the thymus, i.e., right upper, right middle, right lower, left upper, left middle, and left lower, respectively. Upper area means of around the upper pole of thymus, middle area means of around hilum and lower area means of around from lower pole of thymus to diaphragma. In the mediastinal adipose tissue, thymic tissue was found outside the thymus lobes in 41 (75.9%) of 54 patients. The each prevalence (percent of occurrence) of 6 areas were as follows: 15.0% in the right upper area, 21.4% in the right middle area, 19.0% in the right lower area, 17.5% in the left upper area, 66.7% in the left middle area and 33.3% in the left lower area. There was significant differences in the prevalence of the left middle area according to the other 5 areas (p < 0.01). There were no significant differences in the prevalences among sex, Osserman type, duration of the disease, pre-operative treatment and histological findings or removal thymus. There were significant differences in the prevalence of all according to the proportion of thymic tissue in the thymus (0.01 < P < 0.05). In conclusion, it is suggested that for the removal of all thymic tissue, the sufficient procedure required utmost care especially to the left middle area around thymus.(ABSTRACT TRUNCATED AT 250 WORDS)