• Noncollagenous proteins;
  • immunohistochemistry;
  • cholesteatoma;
  • mastoid bone.


Objective Cholesteatoma of the mastoid and middle ear causes erosion of nearby bone. In this study we examined the mastoid bone adjacent to cholesteatoma and compared it with normal mastoid bone. In particular, noncollagenous proteins, which have a special structural and functional role in bone, were addressed.

Study Design Nine mastoid specimens with cholesteatoma and four normal specimens obtained at surgery were examined.

Methods Histological and immunohistochemical methods were employed to evaluate the nature of structure and noncollagenous protein content changes in the mastoid bone affected by cholesteatoma.

Results The bone associated with cholesteatoma had structural changes as a noncontinuous periosteum, empty lacunae, irregular cement lines, and, specifically, the appearance of eosonophilic vesicles at the interface between the bone and cholesteatoma. Immunohistochemistry demonstrated that noncollagenous proteins were apparently absent in the affected mastoid bone. Bone remote from the cholesteatoma seemed normal.

Conclusions These findings demonstrate for the first time the changes in the noncollagenous protein content in the mastoid bone affected directly by cholesteatoma. These changes could be a result of a direct influence of cholesteatoma-derived products on the osteoblast.