An unusual case of metastatic choroidal deposits of renal cell carcinoma presenting with loss of vision

V Dave, A Shah, S Menon 
 Department of Pathology, Tata Memorial Hospital, Homi Bhabha National Institute, Mumbai, Maharashtra, India

Correspondence Address:
A Shah
Department of Pathology, Tata Memorial Hospital, Homi Bhabha National Institute, Mumbai, Maharashtra
India

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A 71-year-old man presented in August 2018 with gradual diminution of vision in the left eye followed by complete vision loss for 4 months. The patient, a known diabetic, had undergone right radical nephrectomy in 2013 for renal cell carcinoma (RCC). On examination, there was no perception of light and projection of rays in the left eye in comparison to normal perception in the right eye. Pupillary reaction was also sluggish on the left side. Magnetic resonance imaging (MRI) showed focal thickening in the chorioretinal membrane posteriorly at the level of optic attachment which was hypointense on T2W and iso to hyperintense on T1W. B-scan of left eye showed dome-shaped choroidal lesion suspicious of choroidal melanoma. Positron emission tomography with 18F-labeled fluoro-2-deoxyglucose integrated with computed tomography (18F-FDG-PET/CT) revealed a 14 mm × 14 mm FDG avid well-defined soft-tissue lesion in the left lower lung lobe (SUV max 5.37) with multiple lesions in both lung fields, FDG avid lytic lesion in neck of the left femur (SUV max 3.37) along with multiple FDG avid mediastinal lymph nodes (SUV max 6.61). There was no FDG uptake in the eyes. Patient underwent myo-conjunctival enucleation and the specimen was sent for histopathological examination. Gross evaluation revealed a 1.8 cm × 1.2 cm × 0.6 cm whitish firm tumor in the inferotemporal quadrant of the globe. The tumor had an endophytic growth pattern. On microscopy, the tumor was arranged in an organoid pattern with polygonal cells having clear cytoplasm and prominent nucleolus on the choroid in the posterior segment (PS) of the left eye [Figure 1]a, [Figure 1]b and [Figure 2]a. The morphological diagnosis was of a metastatic conventional/clear RCC. On immunohistochemistry (IHC), the tumor showed sparse weak positivity for Paired box gene 8 (PAX8) [Figure 2]b, strong positivity for Cluster of Differentiation 10 (CD10) [Figure 2]c and was negative for Cytokeratin 7 (CK7), S100 [Figure 2]d, and Human Melanoma Black 45 (HMB45), thus confirming a metastatic RCC and ruling out a malignant melanoma. Patient was later started on multitargeted receptor tyrosine kinase inhibitor, Sunitinib.{Figure 1}{Figure 2}

Choroid, by virtue of its rich vascular supply, has the risk of harboring distant metastases, which constitute the most common intraocular malignancy in adults.[1] It is generally a late manifestation of widespread disease and connotes poor prognosis. It can also represent as the primary manifestation of an unknown malignancy.[1] Choroidal metastasis from breast and lung are relatively more common than from the gastrointestinal tract, prostate, kidney, and skin.[1],[2] Shields et al. performed a retrospective chart review of 950 uveal metastasis in 420 patients for 20 years and found that the mean age at diagnosis of ocular metastasis was 58 years with choroid as the most common site of uveal metastasis.[2] However, in their study, only eight cases of metastasis to the choroid were from a renal primary.[2] In a review of case reports by Sountoulides et al., they studied 19 cases of ocular metastasis of RCC; the interval between nephrectomy and ocular metastases ranged from 1 month to 17 years in 10 cases.[3] The features of choroidal metastasis can be very similar to primary melanoma on MRI and therefore obtaining a correct history is of utmost value.[4] On microscopic examination, uveal melanomas are either spindle cell or epithelioid cell type. Epithelioid cell type of melanomas may mimic metastatic poorly differentiated carcinoma.[4] Lineage-specific markers such as CK7, estrogen receptor (ER), progesterone receptor (PR), GATA3 for breast, thyroid transcription factor-1 (TTF-1), Napsin A for lung, CDX2 for colon, PAX8 for kidney, and thyroglobulin for thyroid are helpful for a conclusive diagnosis.[5] Melanoma, however, is positive for melanocytic markers such as HMB-45 and S-100.[5] Following enucleation, specific targeted therapies are given for metastatic RCC, whereas immunotherapy, chemotherapy, or targeted therapies are the standard lines of management in melanomas.[6] The value of correct diagnosis for an optimum management is crucial. This patient presented with choroidal metastasis from a renal primary which is a very rare and unusual occurrence.

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Conflicts of interest

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