Cribra orbitalia: Dissecting an ill‐defined phenomenon

Abstract Cribra orbitalia has been the subject of much discussion since first described in the late 19th century. In particular, its relationship to porotic hyperostosis, anaemia, and malaria has been considered on many occasions. We have examined historical, embryological, developmental, anatomical, and pathological data to try to determine the significance of cribra. We conclude that three separate conditions have been included under this rubric: simple orbital porosity (cribra orbitalia sensu strictu ), which is a normal developmental variant; deposits of periosteal new bone on the orbital roof; and an extensive inflammatory enlargement of the inner face of the orbital roof. These final two classes are pathological conditions that lead to a convex appearance of the orbital roof. In contradiction to authors treating cribra orbitalia as a precursor to porotic hyperostosis, we conclude that there is no evidence that the two are causally related. Consequently, cribra orbitalia sensu strictu should not be used as a surrogate for either anaemia or malaria.