LYMPHO-EPITHELIOMA OF THE THYMUS: NERVOUS AND OTHER CLINICAL SYMPTOMS IN THE ADULT.

IN this paper we are concerned, not with the simple tumours-fibroma, lipoma, lymphangioma, lymphosarcoma, round-cell sarcoma-which occasionally (though rarely) arise in the thymus, as in other parts of the body, but with those which arise from the essential epithelioid cells of the thymic medulla associated in greater or lesser proportion with lymphocyte-like cells (probably really lymphocytes), such as constitute the normal thymic cortex. These primary thymic tumours-true " thymomata "may be termed " lympho-epitheliomata " (Grandhomme, 1900; Schmincke, 1921; Regaud, 1921), and are much less often malignant than are the primary lympho-epitheliomata of the tonsils, pharynx, and naso-pharynx (Cappell, 1934; Harvey, Dawson and Innes, 1937). For recent histological accounts of thymic lympho-epitheliomata, see Wu (1935) and Obiditsch (1937). The thymic lympho-epitheliomata seem in some cases to exert an endocrine effect, and are specially related to myasthenia gravis. Most important and interesting was the original observation by Weigert (1901) of a thymus tumour in a case of myasthenia gravis in which he wrongly interpreted the " lymphorrhages " in the muscles as tumourmetastases. To these questions we will return in the discussion further on, but for a summary of the literature of the subject we must refer to the recent papers by Gold (1935), Meister (1936), Norris (1936), Miller (1940), Blalock et al. (1941), and Poer (1942).