Cabot ring

Cabot ring

A thin, annular, looped or figure-eight structure seen in Romanovsky stained (e.g., Wright stained) RBCs, which appears to correspond to residual microtubules from a mitotic spindle.

DiffDx
Megaloblastic anaemia, lead poisoning and other erythropoietic defects are accompanied by reticulocytosis, polychromatophilia and basophilic stippling, and appear in accelerated erythropoiesis.