Ultrastructural localization of Charcot-Leyden crystal protein (lysophospholipase) to intracytoplasmic crystals in tumor cells of primary solid and papillary epithelial neoplasm of the pancreas.

Charcot-Leyden crystals (CLC), composed of a single protein with lysophospholipase activity, have been traditionally associated with eosinophil-rich disorders. Atypically shaped and typical CLC were noted by electron microscopy in the surgical sample from a patient with solid and papillary epithelial neoplasm of the pancreas. This rare primary tumor of the pancreas with limited aggressive behavior also contained damaged and partially or completely degranulated eosinophils in the tumor stroma. We localized CLC protein by ultrastructural immunogold staining to the CLC within vacuolar structures and in vesicles of tumor cell cytoplasm as well as to the cytoplasm and nucleus of eosinophils in the tumor stroma. These findings provide evidence that epithelial tumor cells contain Charcot-Leyden crystal protein that most likely originates from tumor stroma eosinophils. Tumor stroma eosinophils have generally been associated with improved prognoses in a wide variety of epithelial neoplasms. The role of tumor CLC protein (lysophospholipase) in these settings deserves further investigation.