Histopathological findings in human choroidal melanomas after transpupillary thermotherapy

Abstract

Aims-The eVect of transpupillary thermotherapy (TTT) on human choroidal melanomas was investigated by means of histopathology. Methods-Before enucleation TTT was performed in 11 eyes with a xenon arc photocoagulator with a red filter or a diode laser at 810 nm. The exposure time was 1 minute; the estimated temperature at the top of the tumour was about 65°C. Results-Seven of 11 tumours developed necrosis to a maximum depth of 3.9 mm with a sharp demarcation between the necrotic and the viable part of the tumour. The depth correlated with penetration of heat into the tumour. Scattered small haemorrhages in the transitional zone between the necrotic and the viable part of the tumour were observed in three eyes but large haemorrhages were absent. Ocular media were not aVected owing to the low rate of absorption of radiation at 810 nm. TTT did not cause significant scleral damage. Intrascleral tumour cells with a viable appearance were observed in one eye, where the tumour was almost totally necrotic. Conclusion-Results show that TTT has potential as a conservative therapeutic treatment for choroidal melanomas. (Br J Ophthalmol 1997;81:234-239) Enucleation as treatment of choroidal melanomas is partly replaced by radiotherapy with charged particles or brachytherapy with ruthenium-106 or iodine-125. Irradiation is associated with failures and complications since approximately 50% of eyes develop late complications after brachytherapy.

Falha a longo prazo no tratamento do melanoma de coróide com termoterapia transpupilar

“…Early studies on TTT reported satisfactory and replicable results, but they had a short follow-up time (1)(2)(3)(4) . More recently, different publications have supported a more cautious approach, and there is disagreement regarding the method's results and complications.…”

“…In its early stages it may be indistinguishable from a melanocytic nevus (1) . It usually grows as a globular mass protruding toward the vitreous cavity (1,2) . Ocular melanocytes are generally concentrated on the pigment epithelium, the uvea, and the conjunctival stroma.…”

“…The method can produce necrosis up to a maximum depth of 3.9 mm without affecting structures outside the treatment field. Its advantages include a limited field of action, the fact that it does not need to be conducted in an operating theatre, the preservation of the organ and its function (patients with extra-macular foci may retain good visual acuity), and good survival rates (1)(2)(3)(4) .…”

“…Transpupillary thermotherapy (TTT) has emerged as a therapeutic option since 1998 (1,2) . In this technique, a laser beam -infrared radiation -is applied through the pupil to raise the temperature and destroy tumour tissue through cytotoxicity (1,3) .…”

“…In this technique, a laser beam -infrared radiation -is applied through the pupil to raise the temperature and destroy tumour tissue through cytotoxicity (1,3) . The method can produce necrosis up to a maximum depth of 3.9 mm without affecting structures outside the treatment field.…”