[Pseudo-parasites in histology and cytopathology]

When interpreting smears and specimens, histologist and cytopathologists can be misled by images mimicking micro-organisms especially parasites such as protozoa, mycotic agents or helminths. Although some of these pitfalls are well-known, others can be problematic especially if nature of the contaminant is the same as that of the parasite that it mimics. False protozoa parasites can correspond either to exogenous agents such as spores, remnants of human cells, or inert exogenous particles. Pseudo-yeast images can be due to pollen, starch or soot but especially to cells such as macrophages, spermatozoids, and neurons or to various inert bodies such as pigments or calcifications. Pseudomycotic filaments can result from vegetable silk, asbestos bodies, radiate granules or fibrin. Curschmann's spirals and vegetable fibers can be confused with helminths and bacterial particles or pollen with helminth eggs.