Case Of the Week (COW) 05 May 2013
Answer:
PRIMARY MENINGEAL MELANOMA/MELANOCYTOMA
Findings:
Lobulated relatively well circumscribed lesion noted in the left Meckel`s cave . It appears Hyperintense in T1WI and hypointense in T2WI with gradient blooming, consistent with probable melanin content. Relative enhancement (predominantly in the periphery) in the dynamic contrast enhanced subtracted images The lesion is Hyperdense in CT with few calcific specks.
Discussion:
The possible differential diagnoses for this lesion could be either a vascular lesions like cavernous angioma or thrombosed aneurysm OR calcified menigioma. However a cavernoma was not considered due to the homogenous low signal of lesion in T2W1 with minimal contrast enhancement. A DSA was done which was normal and thus ruled out an aneurysm. The T2 signal intensities and the contrast enhancement patterns did not favour a menigioma. The signal intensities were more consistent with Melanin and Diagnosis of Melanocytoma was made. Primary melanocytomas originate from the leptomeninges. Melanocytomas -relatively benign cannot be distinguished radiographically from more aggressive meningeal melanoma. Signal Changes reflect the paramagnetic effects of stable free radicals in melanin with shortening of both T1 and T2 relaxation times. CT finding is that of a hyperdense mass
Ref: Melanocytoma of the Cavernous Sinus: CT and MR Findings: AJNR: 17, June 1
Contributed By:
Dr. Babu Peter MD, DNB
Associate Professor, Barnard Institute of Radiology, Chennai
Senior Consultant Radiologist, Aarthi Scans, Chennai
Answer:
PRIMARY MENINGEAL MELANOMA/MELANOCYTOMA
Findings:
Lobulated relatively well circumscribed lesion noted in the left Meckel`s cave . It appears Hyperintense in T1WI and hypointense in T2WI with gradient blooming, consistent with probable melanin content. Relative enhancement (predominantly in the periphery) in the dynamic contrast enhanced subtracted images The lesion is Hyperdense in CT with few calcific specks.
Discussion:
The possible differential diagnoses for this lesion could be either a vascular lesions like cavernous angioma or thrombosed aneurysm OR calcified menigioma. However a cavernoma was not considered due to the homogenous low signal of lesion in T2W1 with minimal contrast enhancement. A DSA was done which was normal and thus ruled out an aneurysm. The T2 signal intensities and the contrast enhancement patterns did not favour a menigioma. The signal intensities were more consistent with Melanin and Diagnosis of Melanocytoma was made. Primary melanocytomas originate from the leptomeninges. Melanocytomas -relatively benign cannot be distinguished radiographically from more aggressive meningeal melanoma. Signal Changes reflect the paramagnetic effects of stable free radicals in melanin with shortening of both T1 and T2 relaxation times. CT finding is that of a hyperdense mass
Ref: Melanocytoma of the Cavernous Sinus: CT and MR Findings: AJNR: 17, June 1
Contributed By:
Dr. Babu Peter MD, DNB
Associate Professor, Barnard Institute of Radiology, Chennai
Senior Consultant Radiologist, Aarthi Scans, Chennai