Hematoidin crystals in cervicovaginal smears. Report of two cases

Cervicovaginal smears obtained from two women, one at the 32nd week of pregnancy and the other at the immediate postpartum period, contained hematoidin crystals. These crystals were of a golden color and appeared as radially arranged fine needles forming cockleburrs or as aggregates of small irregular particles, spherules or rhomboids, in most instances associated with or within histiocytes. Hemosiderin pigment was associated with them in small amounts. The presence of hematoidin crystals is not an uncommon finding in cytologic specimens, particularly those obtained by fine needle aspiration of walled-off, necrotizing lesions with a component of hemorrhage. It is a very unusual finding in cervicovaginal smears, probably because of the ability of the uterus to promptly rid itself of blood. Certain aspects of the formation and identity of hematoidin are discussed.