Details

Autor(en) / Beteiligte

• Doyle, Arthur Conan

Titel

Cox-2 Immunohistochemical Expression Conjunctival Nevus and Melanoma

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2016

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Introduction:Conjunctival melanomas are extremely rare tumours, representing only 2% of all malignant lesions of the eye. Both classification and correct diagnosis of ocular melanocytic lesions can be a challenge and ambiguity in diagnosis can result in severe misguidance of management and prognosis.Cyclooxygenase-2 is a prostaglandin synthase linked to tumour proliferation and metastization. COX-2 overexpression has been found in many tumours, including uveal melanoma, where it seems to be a marker of poor prognosis. Furthermore, it has also been proposed as a tool in differential diagnosis between cutaneous melanomas and nevi.Objectives: The main goal of this study is to report the results of immunohistochemical COX-2 expression in human conjunctival melanomas and nevi and discuss its potential use for differential diagnosis between benign and malignant conjunctival lesions.Materials and Methods: Twenty specimens of melanocytic nevi and 20 conjunctival melanomas were collected from the archives of the Ophthalmic Pathology Laboratory from Coimbra University Hospital. Immunohistochemistry detection of COX-2 was performed using a monoclonal antibody and 34 samples were classified, in terms of intensity of staining and percentage of cells with positive reactivity, to achieve a COX-2 total score.Results: Comparing the total score values for group, we were able to conclude that a total number of 3 cases presented a score value = 0 (1 melanoma and 2 nevi), 11 cases a score = 1 (6 nevi and 5 melanomas), 12 cases a score = 2 (5 nevi and 7 melanomas) and 8 cases a score = 4 (3 nevi and 5 melanomas). Four nevi and 2 melanoma samples were not evaluated. There was no statistically significant difference for the immunohistochemical expression of COX-2 in the 2 groups. 87.5% of all nevi showed positive expression for COX-2, 62.5% with moderate/intense scores (2 and 4). 94% of all melanomas showed positive expression for COX-2, 67% with moderate/intense scores (2 and 4). Overall, more than 90% of melanocytic conjunctival lesions express COX-2.Discussion: Accordingly to what was expected, our series showed positive expression of COX-2 in 17 out of 18 melanoma specimens (94.4%). However, our study we were not able to establish a significant difference in COX-2 expression between conjunctival nevi and melanomas. Consequently, COX-2 expression is not exclusive of conjunctival melanomas and cannot be used as a differentiating tool for the more challenging melanocytic conjunctival lesions.