Tuberculous lymphadenitis (tuberculous granuloma)
Tuberculous lymphadenitis is a chronic specific granulomatous inflammation with caseation necrosis. The characteristic morphological element is the tuberculous granuloma (caseating tubercule) : giant multinucleated cells (Langhans cells), surrounded by epithelioid cells aggregates, T cell lymphocytes and few fibroblasts. Granulomatous tubercules evolve to central caseous necrosis and tend to become confluent, replacing the lymphoid tissue. (H&E, ob. x4)
Tuberculous granuloma. Multinucleated giant cell (mature - Langhans type) : 50 - 100 microns, numerous small nuclei (over 20) disposed at the periphery of the cell (crown or horseshoe), abundant eosinophilic cytoplasm. It results when activated macrophages merge. Epithelioid cells are activated macrophages resembling epithelial cells : elongated, with finely granular, pale eosinophilic (pink) cytoplasm and central, ovoid nucleus. They have indistinct shape contour and form aggregates. At the periphery are the lymphocytes (T cells) and rare plasma cells and fibroblasts. Caseous necrosis is a central area, amorphous, finely granular, eosinophilic (pink). If recent, it may contain nuclear fragments. The caseum is the result of giant cells and epithelioid cells destruction. (Hematoxylin-eosin, ob. x20)
Tuberculous granuloma (Hematoxylin-eosin, ob. x20)
s-soft