A 35-year-old woman with a progressive impairment in the vision of the

 

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Doctor's Information

Name : Morteza
Family : Sanei Taheri
Affiliation :Radiology Department,Shohada Tajrish Hospital,SBMU
Academic Degree : Associate Professor of Radiology
Email : This email address is being protected from spambots. You need JavaScript enabled to view it.
Resident : ------------------

 

Case Section

Head & Neck Imaging

 

Patient's Information

Gender : Female
Age : 35

 

Clinical Summary

A 35-year-old woman presented to the ophthalmologist's office with a progressive impairment in the vision of the left eye

 

Imaging Findings

Magnetic resonance (MR) imaging of the orbit demonstrated a single intraocular mass measuring 19 × 11 mm in the superior nasal quadrant and arising from the retina and/or choroid of the left eye. The mass was depicted as mildly hyperintense on T1-weighted MR images and hypointense on T2-weighted MR images. These findings are compatible with a typical malignant melanoma of the choroid

 

Differential Diagnosis

The main differential diagnosis is choroidal metastases (from lung, breast, hypervascular, and hematologic malignancies), which are frequently bilateral (33%) and multiple

 

Final Diagnosis

choroidal melanoma

 

Discussion (Related Text)

Diagnosis of choroidal melanoma is based mainly on the findings from indirect ophthalmoscopy, the clinical history, transillumination, or US and its sequential evaluation. US alone has been reported to have a diagnostic accuracy of greater than 95% (8). At US examination, A-mode US demonstrates a tumor with low-to-medium internal reflectivity spikes on the tumor surface and vascular oscillations. B-mode US demonstrates a domed, lobulated, or mushroom-shaped mass (4). Local invasion can be depicted as choroidal excavation and retinal bowing. At CT, the melanoma is depicted as a nonspecific soft-tissue mass with diffuse moderate enhancement after administration of intravenous contrast material. Calcifications are rare but may appear after therapy. At MR imaging, melanotic melanoma is typically hyperintense on T1-weighted images and hypointense on T2-weighted images and shows diffuse moderate enhancement after injection of gadolinium-based contrast material. This characteristic signal intensity of melanoma is believed to be due to the T1 and T2 shortening effect of paramagnetic stable free radicals with unpaired electrons in the melanin pigment (3,9), which in turn affects the degree of relaxation. Tumors with a higher content of melanin pigment are more hyperintense on T1-weighted images. The enhancement after contrast material administration is associated with an abnormal or absent blood-ocular barrier. Diffusion-weighted MR imaging is routinely used at brain MR imaging examination. Malignant tumors usually show restricted diffusion, with a low apparent diffusion coefficient. Amelanotic melanomas represent 25% of uveal melanomas (11) and are indistinguishable from other amelanotic lesions at MR imaging (T1 hypointense and T2 hyperintense). MR imaging of the orbit is used mainly to detect extraocular extension and to exclude any other disease, rather than to establish the diagnosis.

 

References

http://radiographics.rsna.org/content/31/5/1231.full

 

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