Necrosis in Human Cystic Echinococcosis: An Underrecognized Tissue Reaction Possibly Related to Host Response

Aim: As Echinococcosis stands out worldwide as an important zoonotic cestode infection caused by various Echinococcus species, histopathological features of the disease are worthy of in-depth study. Materials and Methods: Histopathological changes in adjacent parenchymal tissue in patients with cystic echinococcosis (CE) were evaluated. The study included 91 patients 4-80 years of age (mean age: 36.24years). Results: The histopathological findings of 83 specimens were as follows: fibrosis: 77.11%; mono-nucleated cells: 71.08%; necrosis: 67.47%; eosinophils: 51.80%; giant cells: 31.33%; neutrophils: 8.43%. Fibrosis,eosinophils, neutrophils, and giant cell infiltration were observed significantly more often than mono-nucleatedcell infiltration, germinal membranes, and protoscolex existence (P 0.01). Necrosis was noted adjacent to the acellular laminated layer in host parenchymal tissue. Liver and kidneys were significantly more prone to necrosis than other localizations (P 0.01). Necrosis was seen significantly more often in patients with higher IHA titration positivity (P 0.01). Conclusions: As necrosis has not been previously considered in CE, histopathological examination in necrosis-dominant cyst walls should be evaluated for a differential diagnosis. One possible explanation for necrosis as a histopathological finding in CE could be that it occurs as a natural course of its immunopathogenesis.