Development of choroidal neovascularization following transpupillary thermotherapy (TTT) for a small malignant melanoma of the choroid at the posterior pole – A case report

Introduction

The malignant melanoma of the choroid is the most common primary malignant intraocular tumor in adults. There are currently several methods available for the treatment of choroidal melanomas. Among others, hyperthermia represents a therapeutic approach in which infrared radiation is delivered through the dilated pupil, called “transpupillary thermotherapy (TTT)”. The method was initially assumed to cause only a few side effects but gradually more and more complications have been observed. The treatment is associated with a number of vascular responses, for example arterial and venous occlusions. However neovascularizations of the choroid have only been detected twice so far and represent an extreme rarity.

Case report

We report on the case of a 70-year-old patient, who developed a choroidal neovascularization (CNV) after we had performed TTT on a subfoveal choroidal melanoma with a prominence of 3.25 mm and a base of 7.95 mm × 7.87 mm. Due to insufficient regression of the tumor, the TTT was repeated twice. An indocyanine green (ICG) angiography, performed 8 months after the last TTT, showed a sea fern-shaped CNV, situated subfoveally in the area of treatment. However, leakages or accompanying hemorrhages (common in CNVs found in age-related macular degeneration) were not observed.

Conclusion

The development of CNV is known after excessive use of photocoagulation causing damage to the Bruch's membrane/retinal pigment epithelium complex which implies a risk for the development of CNV. The appearance after TTT seems to be exceptional because TTT uses heat at a level below that required for photocoagulation. Our observation could be a sign of intraocular heat damage as a long-term consequence of TTT.