A rare case of primary malignant melanoma of clivus with extensive skeletal metastasis demonstrated on 18F-FDG PET/CT
A 55-year-old woman, presented to the hospital with chief complaints of headache, decreased vision in the left eye, and occasional episodes of vomiting since 3 months. MRI brain revealed altered signal intensity lesion with solid, hemorrhagic, and few cystic components in basiocciput, basisphenoid, clivus, sella, and right petrous apex; displacing optic chiasma superiorly. There was associated soft tissue component extending into cavernous sinus with partial encasement of cavernous segment of right internal carotid artery. CEMR study revealed a large moderately enhancing mass lesion involving the clivus with sellar-suprasellar extension with encasement of bilateral internal carotid arteries suggestive of plasmacytoma/chordoma or metastasis []. She underwent endonasal transsphenoidal excision of clival tumor and the black colored, relatively avascular tumor was confirmed to be melanocytic melanoma of clivus on histopathological examination. The patient was thoroughly examined to rule out any lesion on the skin and mucosa with other investigations including chest X-ray. A week after the surgery, this patient was referred to our department for a whole body 18F-FDG PET/CT scan for restaging. Whole body PET-CT scan was performed after intravenous (IV) administration of 10 mCi of 18F-FDG. PET and contrast-enhanced CT images were acquired and reconstructed to obtain transaxial, coronal, and sagittal views. Fused PET-CT images were then generated. The study revealed residual hypermetabolic well-defined lobulated soft tissue lesion in the basisphenoid and sella turcica region extending into the extraaxial space of right middle cranial fossa causing destruction of the sella turcica, sphenoid sinus, dorsal sella, and clivus; suggestive of residual disease. Also multiple metabolically active skeletal lesions were noted suggestive of skeletal metastasis []. Thereafter, the patient was planned for palliative chemotherapy and brain irradiation.