Intracranial melanocytic meningeal tumours and melanosis oculi: case report and literature review

Abstract

BackgroundMelanocytic meningeal tumours are rare extra-axial neoplasms of the nervous system, with only three reported cases in the cavernous sinus. Herein we describe for the first time the association of ocular melanosis and multiple intracranial melanocytic meningeal tumours, with the presenting lesion being in the cavernous sinus. The importance of this association is discussed together with the diagnostic and therapeutic challenges of the case.Case presentationA 20-year-old man presented with a left sixth cranial nerve deficit; general examination documented only congenital melanosis of the homolateral eye. MRI examination showed a space occupying lesion in the left cavernous sinus, which was followed conservatively for 2 years, until a new space occupying lesion was evident at the level of the right frontal convexity: both lesions presented with neuroradiological characteristics suggestive of melanin content.The frontal convexity lesion was removed: intraoperatively the dura was markedly and diffusely melanotic. Histological examination documented a melanocytic meningeal tumour, with a proliferative index of 3 %. The patient underwent 3D-Conformal Radiation Therapy on the lesion of the cavernous sinus (total dose 5040 cGy), with initial tumour reduction. Three years later, due to a symptomatic growth, he underwent partial removal of the lesion in the cavernous sinus. Histological examination was unchanged. He then received adjuvant Temozolomide with Low Dose Fractionated Radiation Therapy (LD-FRT). Due to further disease progression cisplatin plus fotemustine were administered, concomitant with LD-FRT: after two cycles MRI documented significant disease regression. After a period of apparent disease control, the patient presented with persistent cough and evidence of multiple thoracic metastases, which lead to his death, seven years after presentation.ConclusionsIntracranial melanocytic meningeal tumours are challenging lesions, both from a diagnostic and therapeutic point of view; though rare, the possible association with ocular melanosis should be recognized and might facilitate an early diagnosis. Surgery remains the best possible option when feasible. In the event of partial resection, this “benign” disease might be clinically aggressive.

Usefulness of Neuromelanin Sensitive MRI for En Plaque Meningeal Melanocytoma Involving the Cavernous Sinus: A Case Report

“…Meningeal melanocytoma is frequently found in the upper spinal cord and the posterior fossa, usually forming a mass lesion. 1,3,6) In contrast, meningeal melanocytoma in and around the cavernous sinus is rare, and to the best of our knowledge, only three cases have been reported thus far 7–9) (Table 1). Patients with this subset of the tumor usually become symptomatic in young adulthood.…”

“…In contrast to nodular lesions found in the previous three cases, the lesion in the present case showed an en plaque growth pattern spreading not only along the dura but also into the orbital cavity, making total removal of the lesion without inducing post-operative neurological deficits difficult. Because of the potentially aggressive behavior of this tumor, the residual lesion needs to be followed up closely for regrowth that may occur after several years 9) or for rare malignant transformation. 10)…”

Orbital melanocytoma completely resected with conservative surgery in association with ipsilateral nevus of Ota: Report of a case and review of the literature

“…The lesions are typically isointense to hypointense on T2‐weighted images, with avid contrast‐enhancement . Thus, the classically reported neuroimaging features could not reliably distinguish melanocytic tumors from other most common tumors that may be found in similar locations, most notably meningioma, schwannoma, and malignant melanoma . Melanomas have a similar appearance to melanocytomas, but the tendency of the former to hemorrhage affects imaging characteristics and sometimes helps to distinguish it from melanocytoma …”

Malignant spindle cell tumors of the posterior fossa in children: case series and review of management

“…29 CT imaging reveals an enhancing, isodense to hyperdense extraaxial lesion with dural attachments and no distinct margins. 43,44 Generally, there is no necrosis and minimal to no reactive edema in the surrounding brain tissue. 45 Grossly, tumors are solitary, wellcircumscribed, 2 to 5 cm, moderately firm, and black (or dark brown); histologically, there is a lack of nuclear atypia, mitotic activity, necrosis, and apoptosis.…”

“…48 The GNAQ gene encodes the alpha subunit of G-proteins and is associated with cell surface G-protein coupled receptors. 44 The discovery of mutations in GNAQ in primary leptomeningeal melanocytic neoplasms with constitutively active G-protein subunits in the MAPK pathway provides a rationale for MEK inhibition through the use of trametinib, which is the targeted therapy utilized in our patient.…”