Histopathologic features of koilocytotic atypia: a detailed description.

Consecutive cervical biopsies and available cervical smears of 136 patients were screened for changes of koilocytotic atypia in order to select suitable cases for an electron microscopic search for papilloma-type viruses. The initial screening revealed histopathologic features that have not been stressed sufficiently in previous reports and that are important for the recognition of koilocytotic atypia in tissue sections. Koilocytotic atypia affects the squamous epithelium of the transformation zone. The cells involved show cytoplasmic vacuolization that might be related to their ability to store glycogen. The most characteristic feature of this condition is the peripheral cytoplasmic condensation associated with an increase of tonofilaments. In tissue sections, the squamous epithelium has a coarse textural pattern, illustrated and described in detail in this report. The differentiation of koilocytotic atypia from other lesions of the uterine cervix is essential if its nature and clinical behavior are to be investigated.