【摘要】 我们报道罕见的脉络膜黑色素细胞瘤1例，以视网膜母细胞瘤之诊断行眼球内容物剜除术。患儿14mo，以左眼外斜视约10mo主诉就诊。眼科检查及影像学检查显示视网膜脱离并钙化病灶。患儿诊断为视网膜母细胞瘤，患眼行眼球内容物剜除术。组织病理学检查显示肿瘤细胞体积大，多面体型，核小，胞浆含大量黑色素颗粒，提示脉络膜及睫状体黑素细胞瘤之诊断。以往有脉络膜及睫状体黑色素细胞瘤表现类似与恶性黑素瘤的报道，但是，黑色素细胞瘤表现为钙化病灶及视网膜脱离，被误诊为视网膜母细胞瘤，此病例罕见，以往未见报道。
【关键词】 脉络膜；黑色素细胞瘤；视网膜母细胞瘤
INTRODUCTION
The term Masquerade syndrome (MS) first appeared in ophthalmic literature in 1967 by Theodore to describe a conjunctival carcinoma that presented as chronic conjunctivitis[1]. Since then, MS label has been applied to a group of disorders that mimic ocular inflammatory disease. Although some benign conditions can be considered as MS, frequently the term refers to malignant situations. Moreover, Tsai et al[2] reported that ocular oncology, a subspecialty focus on ocular and orbital malignancies, basicly is a field of uncommon disorders. Subsequently, many reports from MS included case studies on uncommon presentations of uncommon diseases. Although MS like ocular diseases are rare conditions, but they could be potentially fatal.. Special consideration including early diagnosis and good management of MS could reduce the burden of disease with better prognosis of the affected patients. Optic nerve melanocytoma is a benign, none or low progressive lesion. Its self limited and no specific treatment is recommended so far[3]. Just, it is important to clinically differentiate melanocytoma from malignant melanoma. Melanocytic intraocular tumors can grow and exceed their vascular supply, become necrotic, and induce inflammation. They could have atypical presentations including atypical signs which make the diagnosis process very difficult[4].
In rare cases with progressive growth and severe visual loss, transformation into malignant melanoma should be suspected and enucleation of the affected eye must be considered[4]. Here we report a patient with malanocytoma and lesions with calcification and retinal detachment who was diagnosed after enucleation.
CASE REPORT
A 14monthold boy was presented with leukocoria and exodeviation, which for the first time was detected at 4 months of age. There was no history of ocular trauma and no family history of ocular neoplastic disease. Examination under anesthesia revealed an iris mass at 1 oclock, a calcified mass at nasal border of the optic nerve head, and inferior retinal detachment. The right eye was normal. Systemic work up was normal. Orbital CTscan showed calcification of the mass. The patient underwent enucleation of the left eye with diagnosis of retinoblastoma. Histopathologic evaluation revealed involvement of choroid, ciliary body, optic nerve head, and some portions of sclera by neoplastic highly pigmented nevi cells (Figure 1). Bleached preparation showed round to oval cells with abundant cytoplasm, oval nuclei and no obvious nucleoli, consistent with choroidal and ciliary body melanocytoma (Figure 1F). Ultrasonography revealed a mass adjacent to optic nerve head and retinal detachment (Figure 2). The patient was healthy and showed no signs of metastasis at 3 years followup.
DISCUSSION
Melanocytoma is a peculiar variant of nevus that classically occurs in optic nerve head and may have contagious involvement of choroid and sensory retina[5]. It seems to be more frequently encountered in black population[6]. Histologically the melanocytoma is composed of deeply pigmented round to oval nevus cells with benign features. Although optic disc melanocytoma is generally believed to have few local complications, it can grow as to exceed their vascular supply, become necrotic and induce inflammation. A recent study showed that there is some degree of disc edema (25%), intraretinal edema (16%), subretinal fluid (14%), retinal exudation (12%), focal hemorrhage (5%), vitreous seeds (4%), and retinal vein obstruction (3%) in patients with melanocytoma.
Melanocytoma of optic disc was traditionally recognized to be stable lesion with no tendency to grow. However, serial fundus photographs have documented subtle enlargement in 1115% of cases after several years. This mild growth should not be misinstructed as malignant transformation[7]. In rare instance, it can induce severe visual loss due to spontaneous necrosis of the lesion or compressive optic neuropathy. More importantly, it can exhibit malignant transformation into melanoma in 1%2% of cases. Gupta et al[8] reported enlargement of optic disc melanocytoma after 6 year followup that according to Bscan, Ascan, and fluorscein angiography and optic nerve CTscan diagnosed to be benign melanocytoma of optic disc with progressive enlargement. Agarwal et al[9] reported profound visual loss due to necrotic optic disc melanocytoma and associated central retinal vascular obstruction mimicking transformation of melanocytoma. Melanocytoma in white European and those of European derivation are rarely symptomatic, have only moderate effect on visual function and show a few rate of progression over long observation[10]. Kurli et al[11] reported a challenging case presented with painful blind eye and vitreous hemorrhage, total retinal detachment, and large choroidal mass that in fine needle aspiration biopsy (FNAB) was consistent with melanocytoma. After enucleation there were cells with large nuclei and prominent nucleoli, and rare atypical mitosis in small clusters compatible with malignant transformation. Demirci et al[12] reported bilateral melanocytoma of the optic disc in a healthy infant and without other systemic problems that was stable for one year followup. Some association between bilateral optic disc melanocytoma, optic disc hypoplasia, and central nervous system abnormalities such as meningioma and hypopitoitorism have been reported[13]. Systemic evaluation for central nervous system abnormalities is warranted in such cases.
Although many cases of the simulation of the malignant melanoma of the choroids and ciliary body with melanocytoma has been reported in the literatures[14] but as we know melanocytoma mimicking as a calcified lesion and retinal detachment with diagnosis of retinoblastoma has not been reported anywhere.
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