Overexpression of epidermal growth factor receptor restricted to macrophages in uveal melanoma

Objective: To determine whether expression of the epidermal growth factor r eceptor (EGFR) is of prognostic Value in uveal melanoma. Methods: Thirty consecutive patients treated for primary posterior uveal me lanoma by enucleation or local resection were studied. Tumors were examined for EGFR and CD68 expression by immunohistochemistry on formalin-fixed, pa raffin-embedded sections. Extracted DNA from paired frozen tumor and blood samples was examined for loss of heterozygosity on chromosome 3 using polym erase chain reaction-based microsatellite analysis. Immunoreactivity for EG FR was correlated with clinicopathological, chromosome 3, and follow-up dat a. Results: Immunoreactivity for EGFR was observed in 7 (23%) of 30 uveal mela nomas, but was restricted to solitary or small groups of cells with macroph age-like morphology. Immunoreactive cells were confirmed as macrophages usi ng an antibody to the macrophage marker CD68. Chromosome 3 loss, epithelioi d cells, and microvascular loops were detected in 17 (57%), 22 (73%) and 19 (63%) of the 30 tumors, respectively. Metastatic disease was detected in 5 patients (17%). No correlation was found between any of these variables an d EGFR positivity. Conclusions: The absence of EGFR immunoreactivity in tumor cells does not s upport the use of EGFR expression as a prognostic indicator in patients wit h uveal melanoma. Future EGFR studies in uveal melanoma should be interpret ed with caution in view of our findings that tumor-associated macrophages c an express this receptor.