Background: We have previously shown that histologically described microcirculation patterns (MCP) can be visualized with indocyanine green (ICG) angiography. We have designed a prospective study to evaluate the prognostic value of these angiographically imaged MCP in small choroidal melanocytic lesions. In this report we describe the design of the study, characterize the patient collective, and present the first results.
Patients and methods: In this prospective nonrandomized observational study, unilateral choroidal melanocytic lesions with 1.5-5.5 mm maximum apical height are observed until growth is determined according to defined criteria. Variables are demographic parameters, subjective symptoms, subretinal fluid, location and dimension of tumor, hemorrhage, color, orange pigment, and MCP determined by ICG angiography: normal, straight, parallel without crosslinking, parallel with crosslinking, arcs without branching, arcs with branching, loop, and network.
Results: Seventy patients (22 males, 48 females; age: 33-88 years, median: 64 years) have been included up to now: 19 tumors showed growth so far (time to growth: 51-946 days, median: 127 days). The following parameters were statistically significantly correlated with time to tumor growth: flashes (p = 0.082), orange pigment (p = 0.012), subretinal fluid (p < 0.001), maximum basal tumor diameter (p = 0.001), maximum apical tumor height (p < 0.001), parallel with crosslinking (p < 0.001), arcs with branching (p = 0.006), loop (p < 0.001), and network (p < 0.001). Of these, complex MCP (parallel with crosslinking, arcs with branching, loop and/or network) showed the strongest correlation with time to tumor growth in a Cox regression model. Based on our data, the positive predictive value of imaging complex MCP (for growth within 12 months) is 78% and the negative predictive value is 98%.
Conclusion: Our patient collective demonstrates comparable prognostic parameters for time to growth as described in the literature. In addition, the ICG angiographic detection of complex MCP is more strongly predictive of the time to growth than other clinically determinable factors. Thus, we recommend this examination for patients with small choroidal melanocytic lesions, if the patient is to be counseled regarding the likely biologic behavior of his tumor.