Histopathologic and MR Imaging Appearance of Spontaneous and Radiation-Induced Necrosis in Uveal Melanomas: Initial Results

Abstract

Necrosis in uveal melanomas can be spontaneous or induced by radiotherapy. The purpose of our study was to compare the histopathologic and MRI findings of radiation-induced necrosis of a group of proton beam-irradiated uveal melanomas with those of spontaneous necrosis of a control group of patients undergoing primary enucleation. 11 uveal melanomas who had undergone proton beam radiotherapy, MRI and secondary enucleation, and a control group of 15 untreated uveal melanomas who had undergone MRI and primary enucleation were retrospectively identified. Within the irradiated and nonirradiated group, 7 and 6 eyes with histological evidence of necrosis respectively, were furtherly selected for the final analysis; the appearance of necrosis was assessed at histopathologic examination and MRI. Irradiated melanomas showed a higher degree of necrosis as compared with nonirradiated tumors. Irradiated and nonirradiated lesions differed based on the appearance and distribution of necrosis. Irradiated tumors showed large necrotic foci, sharply demarcated from the viable neoplastic tissue; nonirradiated tumors demonstrated small, distinct foci of necrosis. Radiation-induced necrosis, more pigmented than surrounding viable tumor, displayed high signal intensity on T1-weighted and low signal intensity on T2-weighted images. The hemorrhagic/coagulative necrosis, more prevalent in nonirradiated tumors (4 out of 6 vs. 1 out of 7 cases), appeared hyperintense on T2-weighted and hypointense on T1-weighted images. Our study boosts the capability to recognize radiation-induced alterations in uveal melanomas at MRI and may improve the accuracy of radiologists in the evaluation of follow-up MR examination after radiotherapy.

Quantitative Diffusion-Weighted MR Imaging: Is There a Prognostic Role in Noninvasively Predicting the Histopathologic Type of Uveal Melanomas?

“…Briefly, on the DW sequence, the radiologists selected the image in which the tumor showed the greatest extent and placed an oval region of interest (ROI), including almost the maximum surface area of the lesion, while at the same time excluding distortion artifacts and the edge of the lesion with the aim of avoiding partial volume effects; the ROI was mechanically copied on the corresponding ADC map. T1-and T2-weighted images were synchronized with DW images and were thoroughly taken into account to identify tumor morphology and boundaries and to exclude macroscopically detectable necrotic or cystic components [47]. The measurement was repeated three times, resulting in a total of three subreadings for each lesion; the values of the three subreadings were averaged and the mean ADC value was obtained for each tumor and then used in the final analysis.…”

Mixed-Cell Type Choroidal Melanoma in a Middle-Aged Woman

“…It is noteworthy that uveal melanomas generally occur in individuals with light-colored eyes 8 and are possibly associated with long-lasting exposure to ultraviolet (UV-B and UV-A) and visible radiation 9,10 . It has been mentioned that uveal melanoma was more incident in men 11 .…”

“…Most patients develop blurred vision and loss of visual acuity without pain 13 . Pain may be the only symptom observed in patients with uveal melanoma and is possibly related to glaucoma, inflammation, or necrosis 8 . Furthermore, uveal melanoma should be considered as a differential diagnosis in patients with unexplained headaches with or without ocular pain.…”

Magnetic Resonance Imaging in the Clinical Care for Uveal Melanoma Patients—A Systematic Review from an Ophthalmic Perspective

“…In MRI, multiple images with different contrasts are generally jointly evaluated. These different contrasts provide the complementary information needed to distinguish different pathologies such as intraocular masses, associated retinal detachment, necrosis and other treatment related effects [21,22,28,[56][57][58]. For the eye, these contrasts should at least include T2-weighted scans and T1-weighted scans, the latter before and after administration of an intravenous gadolinium-based contrast agent (Figure 2A-C).…”