The prognostic significance of lymphocytic infiltration in malignant melanoma of the choroid.

Lymphocytic and plasmocytic infiltration surrounding a malignant tumor probably represents an immunologic response of the host directed against the neoplasm. It has been documented that lymphocytic infiltration has a favorable effect on prognosis in a number of human tumor systems, including cutaneous melanoma. In the present study, 309 consecutive cases of choroidal melanoma were examined for cellular infiltration, and these data were correlated with other histologic parameters and with prognosis. A intense cellular infiltration was found in 15 tumors (4.9%) and a moderate infiltration in 37 (12.0%). Tumors with cellular infiltration were significantly larger and more vascularized than the remaining tumors, which may be related to the accessibility of the immune system to the tumor. There was a higher percentage of poorly differentiated tumors among the tumors with cellular infiltration. However, it does not appear the cellular infiltration favorably influences the prognosis of choroidal melanoma. The 5-year survival rates of patients with like cell types did not depend upon the degree of cellular infiltration demonstrated by the primary tumor. Although choroidal melanomas are capable of inciting an immune response, this response is apparently ineffective in preventing metastatic spread.