Nosematosis of the cornea. Case report, including electron microscopic studies
M. Pinnolis, P. R. Egbert, R. L. Font and F. C. Winter
A 26-year-old woman underwent enucleation of a blind, painful eye because
of a perforated corneal ulcer. Histopathologic examination of the eye
disclosed an acute, necrotizing keratitis surrounding myriad small (2.5 to
3 x 4.5 to 5 micrometer), oval, faintly visible structures. Under polarized
light, they were partially birefringent and stained intensely positive with
the acid-fast technique. The organisms were located mainly within the
cytoplasm of histiocytes in the deep corneal lamellae. They were
interpreted as a protozoa of the genus Nosema. The diagnosis was confirmed
by electron microscopic studies. The distinguishing features between Nosema
species and Encephalitozoon are discussed. To our knowledge, this is the
second documented case of corneal nosematosis.
