Introduction {#sec1-1}
============

Uveal malignant melanoma is the most common primary intraocular malignant tumor in Caucasians though it is relatively rare in Asian Indian eyes.\[[@ref1]\] It can affect any part of the uveal tract, but posterior choroidal melanoma are most common (86.3%), followed by iris and ciliary body melanomas.\[[@ref2]\] In the last few years, fluorodeoxyglucose (FDG) positron emission tomography- computed tomography (PET-CT) scan has emerged as a new imaging modality for the detection and staging of cancer affecting any organ of the body.\[[@ref3]\] It has been also tested in choroidal melanoma with equivocal results. We report three cases of choroidal malignant melanoma in Asian Indian eyes, where FDG PET-CT scan was not very reliable in giving a clear diagnosis.

Case Reports {#sec1-2}
============

Three eyes of three patients, who presented with a pigmented intraocular mass lesion, were included in the study. All patients were males with a mean age of 54 years. Clinically, all eyes had a macula sparing choroidal mass lesion with a mean largest basal diameter of 14.1 mm and mean apical diameter of 9.4 mm. Complete ocular examination was done including best-corrected visual acuity assessment, slit lamp examination, indirect ophthalmoscopy and B-scan ultrasonography before doing the FDG PET-CT scan. The baseline characteristics of the cases are given in [Table 1](#T1){ref-type="table"}. All the lesions were classified according to Collaborative Ocular Melanoma Study group classification.\[[@ref4]\] Whole body PET scan for all three cases showed a low to moderately activity with minimal to moderate FDG uptake for the intraocular tumors \[Figures [1](#F1){ref-type="fig"} and [2](#F2){ref-type="fig"}\]. The mean standardized uptake value (SUV) was 2.3 (range 1.3--3.4). None had any systemic metastasis.

###### 

Baseline characteristics of the cases with PET scan values

![](WJNM-15-53-g001)

![(a) Transaxial computed tomography scan image of case 3 showing the intraocular mass in right eye (black arrow). (b) Fused transaxial image and (c) positron emission tomography transaxial images showing poor fluorodeoxyglucose uptake with maximum standardized uptake value 1.3](WJNM-15-53-g002){#F1}

![Fused positron emission tomography-computed tomography image of case 1 showing moderate fluorodeoxyglucose uptake in the intraocular mass in left eye (black arrow) with maximum standardized uptake value 3.4](WJNM-15-53-g003){#F2}

Treatment given was enucleation for case 1 while other two cases underwent ophthalmic brachytherapy using I-125 seeds with good regression. Histopathological examination of the enucleated eye showed mixed cell type of choroidal melanoma. The mean followup was 14 months (range 12--18) and none developed any systemic metastasis.

Discussion {#sec1-3}
==========

Like many intraocular tumors, diagnosis of choroidal melanoma can be made clinically with an accuracy of 99.5%\[[@ref4]\] and seldom biopsy is required for confirmation. FDG PET-CT scan is fast becoming the standard of care for diagnosis and staging any form of malignancy.\[[@ref3]\] In choroidal melanomas, though it has shown to be quite accurate in picking distant metastasis,\[[@ref5]\] it is not very accurate in diagnosing the primary intraocular mass especially the small and medium sized ones.\[[@ref6]\] In our series one tumor was medium sized while the other two were large tumors and none showed good FDG uptake. In another study the authors concluded that FDG PET-CT scan is a good tool in diagnosing nodular melanomas but not the diffuse infiltrating types.\[[@ref7]\] In our series, all three were nodular, and all showed poor activity on PET-CT scan. Some authors\[[@ref8]\] have kept SUV ≥ 4 as a risk factor for metastasis for choroidal melanomas while others have kept the cut off as 2.5.\[[@ref9]\] However none is universally accepted. The mean SUV for our study was 2.3 and none developed any systemic metastasis till the mean final follow-up of 14 months. Loss of chromosome 3 in the tumor has been associated with high risk of metastasis and positive FDG uptake.\[[@ref10]\] Lack of chromosome 3 analysis and small sample size are the drawbacks of our study. In summary, although FDG PET-CT is fast becoming the gold standard for diagnosis and staging any form of malignancy, caution is advised in interpreting the results of a low uptake of FDG in setting of clinically suspected intraocular choroidal melanomas, especially in Asian Indian eyes.

**Source of Support:** Nil

**Conflict of Interest:** None declared.
