Microscopically, the picture presented by the gland is that of a non-suppurative lymphadenitis. The peripheral sinuses are markedly distended and the channels through the gland share in the change (66). The sinuses contain serum, red blood cells, and mononuclear cells for the most part, but occasionally polymorphonuclear leucocytes are also encountered. More rarely still, a megalokaryocyte finds its way into the sinus. The most characteristic feature is the presence of phagocytosed cells,—a picture comparable with that found in the typhoid lymph node. The nuclei of the phagocytic cells are vesicular and usually stand out sharply in contrast with the pyknotic nuclei of the included cells. There is conclusive evidence that the phagocytes arise from the lining cells of the channel wall, as in typhoid fever, for these cells are frequently in process of division (Fig. LIV). The blood vessels of the lymph gland, greatly congested, contain almost exclusively red blood cells. As a rule, the lymph follicles and the lymph cords take little part in the process. If there is any change in these structures, it is a rarefication. Occasionally, hemorrhage is encountered in a follicle or even in a cord, and this hemorrhage may involve not only the cells of the cord, but its supporting reticular structure, and may form the nucleus of a subsequent necrotizing or suppurative focus.
FIG. XXXI. AUTOPSY NO. 100. ACUTE FULMINATING BRONCHIOLITIS AND BRONCHOPNEUMONIA. NOTE THE NECROTIC ALVEOLAR WALLS AND THE MASSES OF BACTERIA IN THE EXUDATE. COMPARE FIGURES VIII, XVII, AND XXXII. ]
The picture that has been detailed is subject to modification in those cases particularly where a leucocytic reaction is associated. Then, there may be more polymorphonuclear leucocytes in the sinuses, and necrotizing foci may be converted into miliary abscesses.
The change in the bronchial lymph glands cannot be considered other than an expression of an aplastic, inflammatory reaction. It finds an analogue especially in diseases like typhoid fever. The most constant picture includes an edematous, hemorrhagic reaction in which there is phagocytosis of sieved-out cells by the scavengers generated within the gland. Where necrosis or suppuration occurs, and this is rare, it may be considered as a complication.