Benign iris tumors

Up to 84% of iris tumors are benign, more than half of them (54-62%) are myogenic in nature.

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Leiomyoma of the iris

Iris leiomyoma develops from the pupillary muscle elements, is characterized by extremely slow growth, and can be pigmented or non-pigmented. The variety of tumor colors can be explained by the morphogenesis of the iris. The fact is that the pupillary muscles of the iris are formed from the outer layer of the pigment epithelium of the iridociliary rudiment. During embryogenesis, the sphincter cells of the iris produce melanin and myofibrils, while in the postnatal period the ability to produce melanin disappears, while the dilator retains it. This can explain the appearance of non-pigmented leiomyomas developing from the sphincter and pigmented leiomyomas formed from the dilator elements. The tumor is diagnosed mainly in the third to fourth decades of life.

A non-pigmented iris leiomyoma grows locally as a yellowish-pink translucent protruding node. The tumor is localized along the edge of the pupil or, less commonly, in the root zone (in the area of the ciliary crypts). The tumor borders are clear, the consistency is loose, gelatinous. Translucent growths are visible on its surface, in the center of which are vascular loops. Leiomyoma located at the edge of the pupil leads to eversion of the pigment border and a change in its shape. When the tumor is localized in the ciliary crypt zone, one of the first symptoms is an increase in intraocular pressure, so such patients are often diagnosed with unilateral primary glaucoma.

Pigmented leiomyoma of the iris has a color from light to dark brown. The shape of the tumor can be nodular, planar or mixed. It is most often localized in the ciliary belt of the iris. A change in the shape of the pupil is characteristic, its elongation due to the eversion of the pigment border directed towards the tumor. The consistency of the pigmented leiomyoma is denser than that of the non-pigmented one, the surface is bumpy, newly formed vessels are not visible. Tumor growth into the angle of the anterior chamber by more than 1/3 of its circumference leads to the development of secondary intraocular hypertension. Signs of tumor progression are considered to be changes around the tumor: smoothing of the iris relief and the appearance of a zone of pigment spraying, pigment tracks directed to the sides of the tumor, a vascular halo in the iris; the shape of the pupil also changes. Growing into the structures of the anterior chamber angle and the ciliary body, the tumor enters the posterior chamber, causing displacement and clouding of the lens. The diagnosis can be established based on the results of biomicro-, gonio-, diaphanoscopy and iridoangiography. Treatment is surgical: the tumor is removed together with the surrounding healthy tissues (block excision). When removing no more than 1/3 of the iris circumference, its integrity can be restored by applying microsutures. As a result of restoring the integrity of the iris as a diaphragm, the degree of expression and frequency of crystalline lens astigmatism are significantly reduced, and light aberrations are reduced. The prognosis for life is favorable, for vision it depends on the initial size of the tumor: the smaller the tumor, the greater the probability of maintaining normal vision.

Nevus of the iris

The color of the iris and the pattern of the crypts are genetically programmed in each person. Its color is almost uneven in everyone: areas of hyperpigmentation in the form of small spots - "freckles" can be scattered over the surface of the iris. True nevi are classified as melanocytic tumors derived from the neural crest. They are detected in both children and adults. Clinically, a nevus of the iris has the appearance of a more intensely pigmented area of the iris. Its color varies from yellow to intense brown. The surface of the tumor is velvety, slightly uneven. Sometimes the nevus slightly protrudes above the surface of the iris. Its borders are clear, the pattern of the iris on the surface of the nevus is smoothed out, in the central part, where the tumor is denser, the pattern is absent. The size of the nevus varies from a pigmented area of 2-3 mm to large foci occupying one quadrant of the iris surface or more. As the tumor progresses, it darkens and increases in size, a spray of previously unobserved pigment and a ring of dilated vessels appear around it, and the boundaries of the formation become less distinct. Stationary nevi should be monitored. As the nevus progresses, its excision is indicated. The prognosis for life and vision is good.