Clinicopathological and immunocytochemical study of multifocal epithelial hyperplasia

We present the clinicopathological findings after reviewing 52 patients affected by multifocal epithelial hyperplasia (MEH), previously known as focal epithelial hyperplasia and the results of an immunocytochemical study.

We reviewed the clinical files and microscopic slides from 52 MEH-affected patients and new slides were immunostained with a polyclonal antibody against high molecular weight cytokeratins.

More than 95% of the patients were in poverty (<200 dollars monthly family income). Females comprised 71.1% of the MEH patients, 69.3% were in the first and second decades and buccal mucosa, lips, and tongue were more frequently affected. Ninety-two percent of the patients had a direct relative with similar lesions. In hematoxylin and eosin-stained slides, prominent multiple nucleoli were observed. Immunocytochemical study showed differences in immunostaining between lesional and normal cells. Cells with strongly immunostained cytoplasm were seen in the prickle layer of the lesional epithelium as well as in the clinically normal neighboring epithelial tissue. Cytokeratin-negative mitosis-like cells and koilocytes were identified within the lesions.

The name "multifocal epithelial hyperplasia" is more accurate than those previously proposed designations, because it is more precise to describe the clinical and microscopic features of the disease. Also, our results suggest that mitosis-like cells and koilocytes are degenerated cells unable to synthesize cytokeratins and that cells with strongly immunostained cytoplasm represent epithelial cells showing an altered cytokeratin metabolic profile.