Evaluation of proliferative activity in middle ear cholesteatoma using proliferating cell nuclear antigen

Middle ear cholesteatoma has a remarkable invasive activity accompanied by destruction of ossicles and temporal bone. Its aggressive growth and high tendency to recur have impact on the postoperative care of the patients. Proliferating cell nuclear antigen (PCNA) is a 36 KDa DNA-delta-polymerase-associated protein whose level of synthesis has been found to correlate directly with rates of cellular proliferation. In this present study, we used ABC (avidin-biotin complex) technique and monoclonal antibody to PCNA to evaluate the expression of PCNA in 37 cases of cholesteatoma epithelium and 21 cases of normal postauricular skin. The rate of PCNA-positive cells in basal, parabasal, and upper layer of cholesteatoma epithelium tissue is 78% (29 cases), 68% (25 cases), and 41% (15 cases). In each layer of the postauricular skin tissue is 71% (15 cases), 67% (14 cases) and 34% (7 cases). No statistical difference of expression of PCNA-positive cells exists between each layer of cholesteatoma epithelium and normal postauricular skin; however, a tendency of higher PCNA-positive cells in cholesteatoma epithelium was observed. Immunohistochemical method of PCNA has the advantages of spatial architecture preservation, the relative simplicity of the methodology and the rapid acquisition of results. Although the etiology and histopathology of the growth pattern and osteolytic activity of cholesteatoma are unclear, information on cell kinetics may assist in cholesteatoma classification and may help predict the risk of recurrence and bone destruction. The results of this report indicate that cholesteatoma has a similar proliferative activity to the normal postauricular skin, and cholesteatoma itself is not a real tumor, despite its clinical behavior, which is similar to neoplastic cells. It is necessary to further study whether the cell kinetic information we obtained from the PCNA immunohistochemical analysis provides a valuable tool in accessing the prognosis of the cholesteatoma.