Benign Interlobar Hyperplastic Lymph Node Resembling Thymoma

Abstract

We present a case of a tumor in the oblique fissure of the right lung which presented histological characteristics that made difficult differentiation between thymoma and benign hyperplasia of a lymph node. Because ectopia of thymic tumors is rare, attention is called to the occurrence of lymph nodes which can lead to diagnostic confusion, a matter of importance, in view of the difference in prognosis. If thymoma is defined as a tumor of the thymus gland composed always of lymphocytes and reticulum cells in varying proportion, it becomes an entity whose behavior is definite and predictable.^2,13 One of its characteristics is spreading by direct invasion rather than by embolization via the blood and lymph streams, much in the manner of basal-cell carcinoma of the skin.¹⁰ Thus, when tissue resembling a thymoma is found in locations other than the anterior mediastimum its origin becomes a matter for speculation. While