Epithelial migration on the external ear canal wall in normal and pathologic ears

Epithelial migration on the external auditory canal (EAC) wall is abnormal in ears with keratosis obturans (KO). Earlier studies of epithelial migration have focused on the tympanic membrane with scattered information available for epithelial migration on canal walls. This study was undertaken to observe the epithelial migration on the EAC wall in normal ears and in ears with KO. Twenty-five subjects with normal ears and 4 with KO were recruited for the study. Colored ink dots were placed around the tympanic annulus at the 12, 3, 6, and 9 o'clock positions. Migration patterns and the rate of travel of these ink dots were examined and photographed until the ink dots reached the bony cartilaginous junction. Fifteen healthy subjects and 1 with bilateral KO completed the study. The ink dots migrated laterally, with a rate of migration in normal ears between 42 and 205 μm/d. The mean rates for each quadrant, measured clockwise from the 12 o'clock position, were 104.93, 89.80, 72.67, and 109.93 μm/d, respectively. The pathologic ears exhibited a rate between 88 and 140 μm/d, and at approximately 4 to 12 weeks after ink application, areas of abnormal desquamation were apparent at the inferior quadrant, leading to a halt in the migration of the ink dot once it reached these sites. Epithelial migration occurred in an almost linear pattern in all quadrants, but the speed of migration was relatively slower in the anterior and inferior quadrants of a normal EAC. In the single KO patient, there were areas of normal migration and areas of abnormal keratin resurfacing at the inferior quadrant, which interfered with the migration of ink dots.