BACKGROUND
Cholesteatoma consists of keratinizing squamous epithelium, granulation tissue and keratin plugs. The pathogenesis of cholesteatoma may be related to alterations in the stromal immune cell infiltrate.
OBJECTIVE
To examine the immunophenotypic characteristics of the immune cell infiltrate in invasive cholesteatomas
MATERIALS AND METHODS
This study included 12 patients with invasive cholesteatomas causing wide bone erosion of the mastoid, middle ear structures, and the bony plates of middle ear cleft. Diagnosis of invasiveness was based on the clinical, radiological and intraoperative findings. Canal wall-down surgical approach was done in all cases to control the disease process. We used the cholesteatomatous tissue specimens to perform immunohistochemical stains for B cells (CD20), T cells (CD3), histiocytes (CD68) and Langerhans' cells (CD1a). Mouse monoclonal antibodies and immunoperoxidase staining methods were used. The results of immunohistology were scored as mean values of positively stained immune cells. The data were compared with findings in 10 specimens of external ear skin (control group).
RESULTS
Immunohistochemistry showed highly significant (p<0.00) counts of immune cells in invasive cholesteatomas (CD3: 4.7+/-0.4, CD68:4.6+/-0.5, CD20: 0.8+/-0.1 and CD1a: 0.8 +/-0.1) compared to those in external canal skin (control group: CD3:0.8+/-0.3, CD68: 1.0+/-0.4, CD20: 0.2+/-0.1 and CD1a: 0.1+/-0.1). In cholesteatomas, the predominant of CD3(+) T lymphocytes and CD68(+) cells (histiocytes). Rare CD20(+) cells and CD1a(+) cells (Langerhans' cells) were also observed.
CONCLUSIONS
This preliminary study describes the profile of the immune cell infiltrate in invasive cholesteatomas. The numeric dominance of CD3(+) cells and CD68(+) cells suggests that cell-mediated immunity has important role in the development of cholesteatoma and in its autodestructive properties. Further studies are recommended to categorize the T cell subsets in different stages of cholesteatomas.