Abstract
Purpose: :
To differentiate pigmented lesions of the conjunctiva using immunohistochemical markers.
Methods: :
Fifty-three conjunctival nevi, 10 primary acquired melanoses (PAM) without atypia, 25 PAM with atypia, and 24 conjunctival melanomas were analyzed by immunohistochemistry using the alkaline-phosphatase anti-alkaline phosphatase method. Antibodies against melanocytic cells (S-100, HMB-45, Melan-A), t-lymphocytes (anti-CD3), macrophages (anti-CD68), and the proliferation marker Ki-67 were applied. Immunohistochemical staining was assessed semi-quantitatively according to intensity and number of positively staining cells using a grading scale from 0 to 3. Fisher’s exact tests and Mann Whitney tests were employed for statistical analysis.
Results: :
PAM with and without atypia showed significantly different staining for S-100 (p=0.027), HMB-45 (p=0.004), Melan-A (p=0.007), CD3 (p=0.019) and CD68 (p=0.015). Ki-67 expression (p=0.015) and the amount of t-lymphocytes (p=0.018) were significantly higher in conjunctival melanomas compared to PAM with atypia.
Conclusions: :
In addition to cytological characteristics, benign, potentially malignant, and malignant pigmented conjunctival tumors can be differentiated according to their immunohistochemical staining pattern for melanocytic and inflammatory markers. Therefore, immunohistochemistry is a valuable tool in the differentiation of histologically questionable lesions.
Keywords: conjunctiva • tumors • immunohistochemistry