A clockface chromatin pattern in the intermediate megaloblast of vitamin B 12 or folate deficiency.

II ECOGNITION of the fully-developed megaloblast in deficiency of vitamm B12 or folic acid is not difficult. In the case of the “intermediate megaloblast” or “megaloblastoid” cell, however, identification of megaloblastic changes often becomes more difficult, and more subjective.1 The present study attempts to reduce this subjectivity by demonstrating a unique clockface chromatin pattern along the nuclear membrane of fully-developed megaloblasts from patients with a deficiency of vitamin B12, folate, or both. A similar clockface chromatin pattern appeared in intermediate megaloblasts from patients with subsequently confirmed deficiencies of vitamin B12 or folate. In this way, a “clockface sign” in an intermediate megaloblast might provide a morphologic clue to a deficiency of vitamin B12 or folate.