Objective: To establish a molecular biological basis for differentiation of congenital and acquired cholesteatoma.
Study design: The time of onset was estimated for congenital cholesteatoma and for acquired cholesteatoma by comparing the telomere length and the telomerase activity in the tissues of both diseases with the values of those parameters in normal external ear canal skin.
Methods: The telomere length was determined by extracting DNA from each tissue and then applying the Southern blot technique to hybridize it with a 32P-labeled telomeric oligonucleotide (TAAGGG)8 probe. The telomerase activity was analyzed by a modification of the polymerase chain reaction-based telomeric repeat amplification protocol.
Results: The telomere length in congenital cholesteatoma tissue was shorter than the length in normal external ear canal skin from the same patient, whereas in acquired cholesteatoma tissue the telomere length was almost the same as in the normal external ear canal skin. Some of the acquired cholesteatoma tissue specimens and normal external ear canal skin specimens were positive for telomerase activity, but all of the specimens of congenital cholesteatoma tissue were negative for telomerase activity. No correlation was found between the presence of telomerase activity and the telomere length.
Conclusions: The present results indicate that congenital cholesteatoma manifests at an earlier time compared with acquired cholesteatoma, and the results can be thought to support the theory that congenital cholesteatoma originates from vestigial fetal tissue or aberrant tissue. In addition, the finding that telomerase activity was weak in the congenital cholesteatoma tissue suggests the possibility that vestigial fetal tissues and aberrant tissues are naturally eliminated in normal subjects as a result of apoptosis.