Ultrastructure of Peculiar Phagosomes in Stromal Lymphatic Tissue of One Rhinopharyngioma.

Abstract

Four cases of rhinopharyngioma were examined by electron microscopy, special attention being given to the lymphatic tissue adjacent to the tumoral epithelium. The tumor cells showed the typical ultrastructure of the epithelium of rhinopharyngioma (monomorphous population of large cells with clear large nucleus containing one or more nucleoli, cytoplasm with bands of tonofilaments). The lymphatic tissue in 3 of the 4 cases examined did not show any numeric or ultrastructural changes in its cellular components. In the 4th case however, it contained numerous cells which could not be classified definitely according to their morphological characteristics. These cells contained cytoplasmic inclusions of unusual appearance. The inclusions were composed of a finely granular and homogeneous material delimited by a three layered membrane 80 - 90 A in thickness and were intersected internally by membranes of the same thickness arranged sometimes in parallel systems. On the basis of the histochemical characteristics of these membranes, similar to those of the pinocytotic vesicles and to the cellular membrane, these peculiar cytoplasmic inclusions were considered phagosomes. In the lymphatic tissue of the same case, a considerable increase in the number of plasmocytes was observed. The plasma cells had the morphological characteristics of intense secretory activity (very dilated ergastoplasmic cisterns full of dense material sometimes showing a paracrystalline structure). The presence of cells containing peculiar phagosomes and the hyperactivity of the plasmacells were related respectively to a histiocytic activation of various cells of the lymphatic tissue and to an immunological reaction of the plasmocytes, both due to necrosis of the tumor tissue.