Abstract
Purpose :
Uveal melanoma (UM) is a rare but deadly disease with a high tendency of hematogenous spread, preferentially to the liver. Many prognostic factors have been described such as size, histopathologic type, vascular loops, mitotic figures, scleral invasion, and the presence of inflammatory cells. Dual nature cells (DNC), which may correspond to circulating hybrid cells (CHC) encountered in the blood, have combined tumor and leukocytic cell features. These cells have been seen in peripheral blood in UM patients and were found to predict the development of metastasis. The purpose of this study is to determine if DNCs are present in primary UM tumors.
Methods :
A histopathological study of 38 patients with UM was performed and the tumors were examined for high-risk factors such as size, histopathologic type, presence of vascular loops, scleral invasion, as well as inflammatory cells (lymphocytes and/or macrophages). Comparison between the presence of these cells and other high-risk factors was conducted. Tumors were categorized as small when size was 10 mm or less in their maximum dimension, and large when greater than 10 mm. An immunohistochemical panel (IHC) was performed, including HMB-45, Melan-A, CD45, and CD68. In addition, a double labelling IHC stain with HMB-45 and CD45 was performed. To the best of our knowledge, this is the first double labelling stain performed in the primary ocular melanoma.
Results :
From the 38 cases examined, DNCs were present in 63% of the cases. Out of the 24 cases with DNCs, no high-risk factors were found in 4% of the tumors, which were small, at least spindle predominant rather than epithelioid, had no vascular loops, no inflammation, and no scleral invasion. From the rest of the positive cases, 17% had one high-risk factor, 29% had 2 or 3, 13% had 4 and 8% had 5 of the 6 possible high-risk factors. Moreover, no cases had all 6 high-risk factors.
Conclusions :
The pathogenesis of systemic disease and liver metastasis in Uveal Melanoma patients remains unclear. Inflammation, in particular lymphocytic inflammation, is a well-known poor prognostic factor. The presence of inflammation could be indicative of the DNC formation seen within the tumors representing a worse patient prognosis. Ultimately using immunohistochemical methods, the type of infiltrating inflammatory cells should be further investigated for their role in DNC formation.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.