Charcot-Leyden crystals in fine needle aspiration cytology

OBJECTIVE: To study the occurrence and significance of Charcot-Leyden crystals (CLC) in routinely processed, eosinophil-rich smears. STUDY DESIGN: Fine needle aspiration (FNA) smears of 258 cases of cysticercosis, 35 of lymphatic filariasis and 19 of nonparasitic lesions with significant eosinophils were screened for the presence of CLC and correlated with the cytomorphology of the underlying disease. RESULTS: Charcot-Leyden crystals were seen in lymphatic filariasis (4), eosinophilic granuloma (1), chronic myelogenous leukemia (1) and pyogenic abscess (1). CLC were conspicuous by their absence in smears of cysticercosis, although cholesterol crystals were frequently observed. CLC were present in both May-Grunwald-Giemsa- and Papanicolaou-stained smears. Necrosis was a prominent cytologic feature in all cases with CLC. CONCLUSION: CLC encountered in routinely processed aspirates containing eosinophils, albeit infrequently, indicate in vivo formation. Necrosis probably provides a milieu for suspension of eosinophils, facilitating the formation of CLC. Absence of CLC in cysticercosis could be attributed to the high lipid content of these lesions, as indicated by the frequent occurrence of cholesterol crystals.