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L.L. Wayman, K.H. Baratz, L.J. Maguire, D.O. Hodge, D.R. Salomao; Different Patterns of Expression of Cell Cycle/proliferation Markers in Primary Acquired Melanosis With (PAMA) and Without Atypia (PAM) . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2428.
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Purpose: To determine whether the expression of cell cycle/proliferation markers could be useful in distinguishing between PAM and PAMA, using benign conjunctival nevi and malignant melanomas as control groups. Methods: A computer-based search was done to identify consecutive biopsies performed for melanocytic lesions of the conjunctiva in our institution between January 1982 and August 2000. Cases with tissue available in paraffin blocks were tested by immunoperoxidase studies using the following commercial antibodies: HMB45, MIB-1 (antiKi-67), bcl-2, and p27. The percentage of positive biopsies, determined by the presence of any positive cells, was compared among the various groups using Fisher's exact test. The proliferation index with MIB-1 was determined by the percentage of positive nuclei (<10% was considered low and >10% high). The results were adjusted for the 6 possible comparisons among the four groups using a Bonferroni adjustment. Results: 83 biopsies obtained from 70 patients (11 PAM, 12 PAMA, 26 melanomas, and 34 nevi), of those 40 were women and 30 were men, with average age 51 years (+ 23), were included in this study. The results of the immunostains, percentage of positive cases, are shown in the table below: Statistically significant differences were observed between PAM and PAMA for bcl-2, p<0.001; MIB-1, p=0.04 and the melanocytic marker HMB45, p=0.04. The results for PAMA were similar to the results observed in melanoma cases. The proliferation index in PAM was zero, low in PAMA and nevi and high in malignant melanoma. The results for the p27 marker were not significantly different between the groups. Conclusions: There was a distinct pattern of expression of bcl-2 proto-oncogene and MIB-1 (42% positivity versus 0%) in PAMA when compared to PAM. HMB45 reactivity was also different between these two entities. These results may explain the differences in clinical behavior and relative risk to develop malignant melanoma and may be helpful to distinguish cases with equivocal morphology. View OriginalDownload SlideView OriginalDownload Slide
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