Caseous necrosis

Caseous necrosis (from Latin caseus – cheese) is a specific type of coagulation necrosis of tissues, characteristic of chronic granulomatous inflammation, primarily of tuberculous etiology.

In this process, the dead tissue turns into a dry, crumbling, structureless mass of yellowish-white color.

Etiology and pathophysiology

The development of necrosis occurs in the center of the tuberculous granuloma. The mechanism of its formation is associated with delayed-type hypersensitivity reaction (type IV). Toxic lipid fraction of mycobacterial cell wall and lysosomal enzymes of activated macrophages cause complete destruction of the tissue.

Histologically, caseous necrosis is an eosinophilic amorphous detritus in which cell structure, nuclei, and tissue architecture are completely lost (“graveyard of dead cells”). A shaft of epithelioid cells and giant multinucleated Pirogov-Langhans cells is formed around the necrosis zone.

Clinical significance

Histologic verification of caseous necrosis in endometrial, fallopian tube or ovarian biopsy is an absolute and indisputable criterion for the diagnosis of genital tuberculosis. This allows reliable differentiation of tuberculosis from other granulomatous diseases such as sarcoidosis (where granulomas are non-caseous) or Crohn’s disease.