Immunobiological peculiarities of cholesteatoma in children: quantification of epithelial proliferation by MIB1.

Cholesteatoma in children is characterized by a more extensive and rapid growth in the middle ear and mastoid cavities. The growth characteristics of the cholesteatoma in 20 children were studied using the monoclonal antibody MIB 1, which recognizes a nuclear antigen expressed by cells in the G1, S, and G2/M phases. Specimens of normal adult auditory meatal skin (n = 15) and adult cholesteatoma (n = 15) served as controls. The tissue specimens were prepared for immunohistochemical examination using the alkaline phosphatase-antialkaline phosphatase method and an automatic image analyzer. Specimens of normal skin revealed an average MIB 1 score of 9.2 +/- 3.10%. Child and adult cholesteatomas showed higher values. The average MIB 1 score was higher in child cholesteatoma (42 +/- 9.4%) than in adult cholesteatoma (28.2 +/- 6%). This difference was statistically significant (P<.01). Our results confirm a significant increase of the proliferative rate of cholesteatoma keratinocytes in children, giving an explanation for the more aggressive clinical behavior observed in these patients.

Identification of proliferating keratinocytes in middle ear cholesteatoma using the monoclonal antibody Ki-67.

Cholesteatoma epithelium is characterized by a keratinocyte dysregulation with aggressive growth subsequently destroying the middle ear mucosa. The monoclonal antibody Ki-67 recognizes a nuclear antigen expressed by cells in the G1, S, and G2/M phases being used to determine the growing cell fraction in tissue samples. Cryostat sections of skin and cholesteatoma biopsies were examined immunohistochemically for reactivity with Ki-67 using the alkaline phosphatase-anti-alkaline phosphatase method. Nuclear staining was seen in a small number of keratinocytes located in the basal cell layer of normal auditory meatal skin. In contrast, numerous cells of the basal and suprabasal layers in cholesteatoma were found to react with Ki-67. A cytoplasmic staining was also observed in both skin and cholesteatoma. In cholesteatoma, the cytoplasmic staining was stronger. These results clearly show that cholesteatoma epithelium proliferates at a higher rate than normal epidermis, confirming the hyperproliferative behavior of cholesteatoma.