Abstract
Purpose: :
Evaluate the expression of cyclooxigenase-2 (COX-2), C-KIT and platelet derived growth factor receptor (PDGFR) alfa and beta in melanocytic lesions of the conjunctiva and their role as new therapeutic targets.
Methods: :
Formalin-fixed, paraffin-embedded sections of 45 melanocytic conjunctival lesions were retrieved from the archives of the Henry C. Witelson Ocular Pathology Laboratory, McGill University. Twenty-two nevi, 17 primary acquired melanosis (PAM) and 6 Conjunctival melanomas (CM) were stained with Hematoxylin and Eosin (H&E) for histopathological assessment. Immunohistochemistry using the antibodies against COX-2, C-KIT and PDGFR alfa and beta was performed using the Ventana BenchMark (Ventana Medical Systems Inc, Tucson, AZ, USA) fully automated machine. Samples were classified as negative, weak and strong by two independent pathologists based on the intensity of the immunostaining. Conflicting results were resolved by mutual agreement.
Results: :
All the markers, especially COX-2, C-KIT and PDGFRa, showed at least in some extent high positivity in the melanocytic lesions. The expression of COX-2 was positive, in all the nevi, PAM and CM studied. C-KIT expression was positive in 95.5 % of nevi, 94.1% of PAM and 100% of CM. Positive expression of PDGFRa was observed in 90.9 % of nevi, 94.1 % of PAM and 100 % of CM. PDGFRb expression was positive in 100 % of nevi, 76.5 % of PAM and 83.3 % of CM. Expression of COX-2 was found to be significantly higher in nevi melanocytes (90.9%) compared with CM melanocytes (33.3%) (P=0.009).
Conclusions: :
In the present study, for the first time, the expression of COX-2, C-KIT, PDGFRa and PDGFRb was evaluated in melanocytic lesions of the conjunctiva. Significant expression of those markers was observed. Thus, treatment options modulating these targets may prove beneficial as an additional modality in the management of pre-malignant and malignant disease.
Keywords: immunohistochemistry • conjunctiva • tumors