Cytologic Diagnostic Aspects Of Different Echinococcal Structures In Various Cytologic Preparations Of Hydatidosis

Hydatidosis is a slow-growing disease caused by Echinococcus species, most commonly affecting the liver and lung. In this study, we focused on detailed morphologic features of Echinococcus in various cytology preparations acquired by fine needle aspiration, namely Papanicolaou and Romanowsky (Diff-Quik) staining on liquid-based (ThinPrep), direct smear, and cytospin slides, and hematoxylin and eosin (H&E) cell block sections. Two patients presented to our institution with significant peripheral blood eosinophilia up to 19% (2.76 K/mm3); imaging studies showed similar 9 cm cysts in the liver. Aspiration of the cysts demonstrated yellow cloudy fluid, termed hydatid sand. Cytologic studies showed numerous parasite structures, including protoscoleces and scoleces; degenerating forms contained multiple calcareous corpuscles, a feature commonly seen in cestodes. Unstained refractile hooklets with a sharp, curved distal end and two proximal blunt projections, were also present throughout the specimens. Partial acellular laminated cyst wall was noted only on cell block. Liquid-based cytology removed the dirty background of hydatid sand and demonstrated the best preservation of parasite structures. This allowed for easier identification compared to Romanowsky stain, which still contained abundant background debris. Conclusions: Our recommendations are that: 1/all routine cytology preparations are necessary to maximize the chance of parasite detection, especially for specimens with low parasite content, 2/liquid-based preparations best visualize parasite components, and 3/cell block is useful for demonstration of the cell wall; thereby giving a complete cytopathologic picture of Echinococcal disease.