primay melanoma of the cavernous sinus is very rare , and neuroimaging findings have been described in a few reports . we describe the case of a 36-year - old female who presented with left cavernous sinus mass lesion with imaging characteristic of melanin - containing tumor . the differential diagnosis of cavernous mass lesion is reviewed followed by a discussion of particular characteristics of melanin pigment on cross - sectional imaging . a 36-year - old female presented with headache since 3 years , reduced sensation over left half of the face , difficulty in chewing from left side of the mouth , and diplopia for the last six months . . left lateral rectus palsy , mild ptosis , left temporalis , and masseter muscle wasting with reduced sensation over v1 , v2 , v3 by 50% , corneal reflux absent , and grade 2 facial palsy was noted . an unenhanced computed tomography ( ct ) scan of the brain showed a hyperdense mass in and adjacent to the left cavernous sinus and petrous bone [ figure 1 ] . neither calcification within the lesion nor hyperostosis of the adjacent bony structures noted . on magnetic resonance imaging ( mri ) , the mass appears to be predominantly hypointense on t2-weighted axial mri [ figure 2a ] , predominantly hyperintense on t1-weighted coronal image [ figure 2b ] , with no significant enhancement on post - contrast t1-weighted axial images [ figure 2c ] and mild blooming in centre due to hemorrhage [ figure 2d ] as well as some cystic degeneration . unenhanced axial computed tomography scan shows a heterogeneous hyperdense mass in and adjacent to cavernous sinus and petrous bone which appear oval with elongation into the meckel 's cave . ( a ) axial t2-weighted mri shows an extracranial mass which is appearing predominantly hypointense with central areas of hyperintensity due to cystic degeneration and haemorrhage . ( b ) coronal t1-weighted mri shows the mass to be predominantly hyperintense with central areas of hypointensity . ( c ) axial t1-weighted post contrast mri shows the mass to be predominantly hyperintense without any appreciable enhancement . ( d ) axial susceptibility weighted image ( swi ) shows mild blooming in centre suggestive of hemorrhage left frontotemporal craniotomy and biopsy of the lesion revealed extra - axial black - colored mass in the left cavernous sinus region between v2 and v3 division of the 5 cranial nerve . it was firm but friable in consistency and there was xanthochromic fluid within a cyst in the tumor . telephonic follow - up after 1 month showed significant symptomatic improvement without any new symptoms . primary malignant melanoma of the central nervous system comprises approximately 0.1% of the brain tumors . primary malignant melanoma in the vicinity of the sellar turcica is even rare , with only few reports in the literature . the explanation for the histogenesis of primary melanoma in the vicinity of cavernous sinus is that these tumors could arise from melanocytes in the leptomeninges . the differential diagnosis for cavernous sinus mass lesion is wide because it contains vital neurovascular structures that may be affected by vascular , neoplastic , infective , and infiltrative lesions arising in the cavernous sinus proper or via extension from the adjacent intra and or extracranial regions . the clinician needs to know the type of cavernous sinus lesion , its relationship , and its extension so that appropriate treatment can be started . radiologic imaging can narrow the differential diagnosis , however , imaging can not definitely reach single diagnosis if mass lesions present in the atypical form with hemorrage and cystic degeneration . primary meningeal melanocytic tumors include a spectrum of meningeal tumors , benign end of which is represented by melanocytoma whereas the malignant end is represented by primary or secondary meningeal melanomas . the more aggressive meningeal melanoma have the propensity to metastasize , however , in our case , no distant spread or other primary foci of melanoma was identified . an unenhanced ct scan in melanoma shows a hyperdense lesion , as seen in our case . mri and angiography exclude aneurysm and meningioma because the lesion was appearing hyperintense on t1 and hypointense on t2-weighted images with no direct communication with carotid artery . there was medial displacement and narrowing of the cavernous carotid artery , suggesting an intradural lesion . the mr findings narrowed the differential diagnosis to melanomatous neoplasm , cavernous angioma , or dermoid / white epidermoid tumor . the typical mr findings in intracranial melanoma include shortening of t1 and t2 with characteristic hyperintensity to brain parenchyma on t1-weighted images and hypointensity on t2-weighted images , presumably due to the paramagnetic effects of melanin , as in our case . cavernous angiomas appear hyperdense on ct scan and appear t1 isointense and t2 hyperintense on mri with strong progressive post - contrast enhancement and variable hemosiderin deposits . lipid - like material can also produce the same mr signals as melanin , however , they may be distinguishable on ct by attenuation . another useful diagnostic tool for the detection of intracranial melanoma could be the demonstration of an increased uptake of i - iodoamphetamine in single - photon emission computed tomography ( spect ) . once the diagnosis of melanoma is established , the exclusion of a primary melanoma in other organs proves to be the most important issue by thorough clinical examination , paying attention to the dermatologic , ophthalmologic , and sinonasal areas ; in our case , a thorough clinical examination was done to exclude any other organs having melanoma or metastasis . the melanoma may be primary or metastatic and the primary form may arise from the skin or other sites such as the uvea , meningeal , sinonasal mucosa , prostate , urethra , etc . , metastatic melanoma occurs when melanoma cells of any kind ( cutaneous , mucosal , or occular ) have spread through the lymph nodes to distant sites in the body . the liver , lungs , bones , and brain are most often affected by these metastasis . the treatment modalities include surgical excision , stereotactic radiosurgery , and/or boron neurtron caputre therapy . in conclusion , primary melanoma of the cavernous sinus is a very rare tumor and can have atypical characteristic if associated with hemorrhage and cystic degeneration . the differential diagnosis for cavernous sinus lesion is wide ; however , a meticulous radiological approach can narrow the differential diagnosis so that an appropriate treatment can be initiated .
primay melanoma of the cavernous sinus is very rare with only few cases reported in the literature . 
 we present the cross - sectional imaging findings of this rare tumor . 
 the differential diagnosis for cavernous sinus mass lesion is wide as it contains vital neurovascular structures that may be affected by vascular , neoplastic , infective , and infiltrative lesions arising in the cavernous sinus proper or via extension from adjacent intra and/or extracranial regions . 
 radiologic imaging can narrow the differential diagnosis , however , imaging can not definitely reach single diagnosis if they present in atypical form with hemorrage and cystic degeneration . 
 this case report illustrates that primary cavernous sinus melanoma may present as a atypical tumor with diagnostic dilemma .