Blood supply is known to be required for tumor growth and metastasis, and the formation of the tumor’s own vasculature plays a critical role in the development of solid neoplasms. The method of optical coherence tomography angiography (OCTA) is considered promising for the study of angioarchitectonics.

PURPOSE

To evaluate the OCTA signs of choroidal melanoma (CM) depending on its sizes.

MATERIAL AND METHODS

The study included 24 patients with CM (24 eyes, of them with small CM — 22 eyes) aged 55.0±12.08 years (37 to 80 years old) with mean prominence of 2.35±0.87 mm (1.0 to 4.7 mm).

RESULTS AND DISCUSSION

Retinal vascular attenuation in the tumor area was observed in 21 eyes. Changes in angioarchitectonics in the area of CM localization can be detected at a thickness of 1 mm, and the tumor’s own vasculature — starting with a thickness of 1.4 mm. The development of vascular changes in CM can be represented as follows: initially, with CM prominence of up to 1.4 mm, indirect signs of increased blood flow in the overlaying choriocapillaris layer are visualized, most likely due to its compression; as the tumor grows and its thickness increases in its most dominant part, the choriocapillaris layer is completely destroyed, which leads to reactive expansion of the choroidal capillaries along the layer’s edges. This is manifested as attenuation of the vascular signal in the central part of the tumor and its intensification along its edges. In the meantime, collaterals begin to form in the deep vascular plexus of the retina. Later on, chaotic vascular arches begin to form in the inner layers of the choroid along the tumor edge; as the tumor grows, they anastomose with the retinal vessels. Identification of the tumor’s own vessels in the deeper-lying layers is possible with tumor prominence of at least 1.4 mm. At the level of the deep choroidal layers, the tumor’s vascular pattern is more consistent with the angiographic data and patterns of vasculogenic mimicry described in literature.

CONCLUSION

Changes in angioarchitectonics in the area of CM localization can be detected at a thickness of 1 mm, and the tumor’s own vasculature — starting with a thickness of 1.4 mm. The vascular pattern at the level of the deep choroidal layers best corresponds to the reported angiographic picture and patterns of vasculogenic mimicry.