ELECTRON MICROSCOPY OF GRANULOMATOUS LESIONS OF THE LIVER IN PRIMARY BILIARY CIRRHOSIS

Three granulomas in the portal tract and 9 bile ducts with typical features of chronic non-suppurative destructive cholangitis (CNSDC) associated with dispersed epithelioid.cells were examined by electron microscopy in 10 patients with primary biliary cirrhosis (PBC). Vesicular epithelioid cells, which contained numerous single-membrane bound vesicles, predominated in the granulomas. On the other hand, immature epithelioid cells and activated macrophages were more often observed near epithelial cells of the bile ducts with CNSDC than in the granulomas. These macrophages seemed to be activated by epithelial cells of the bile ducts and develop into epithelioid cells. Honeycomb-like membranous labyrinths containing electron dense substances were frequently observed in epithelioid cells and were likely a special form of phagosome. The substances in the labyrinths seemed to be derived from organellae of necrotic cells and extracellular interstitial tissues. Subplas-malemmal linear densities (SPLD) were observed at the cytoplasmic boundary and at intracytoplasmic membranous labyrinth. The roles of SPLD were discussed. ACTA PATHOL. JPN. 35 : 1309–1318, 1985.