An oncocytic medullary carcinoma is characterised by polygonal discohesive cells with poorly defined cell borders and relatively bland nuclei, which are round to oval with salt and pepper chromatin. An oncocytic medullary carcinoma is characterised by polygonal discohesive cells with poorly defined cell borders and relatively bland nuclei, which are round to oval with salt and pepper chromatin. Immunohistochemistry confirms positivity for chromogranin, calcitonin, and carcinoembryonic antigen. S L Asa J Clin Pathol 2004;57:225-232 Copyright © by the BMJ Publishing Group Ltd & Association of Clinical Pathologists. All rights reserved.