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Primary Intracranial Brainstem Malignant Melanoma: A Technical Case Report
Margaret McGrath1, Samuel Emerson1, Varadaraya Satyanarayan Shenoy1
1Department of Neurological Surgery, University of Washington, Seattle, Washington, USA.
Background And Importance:
Primary intracranial malignant melanomas (PIMMs) are quite rare, comprising 1% of melanomas and 0.07% of intracranial tumors. PIMMs have been reported in a variety of intracranial locations, but there has only been 1 reported instance of PIMM occurring in the brainstem. In this study, we describe the second reported case of primary pontine malignant melanoma and its treatment.
Clinical Presentation:
A 40-year-old man presented with right hemiparesis, diplopia, and dysarthria. MRI demonstrated a hemorrhagic, expansile, and heterogeneously enhancing lesion in the left pons with edema extending to the left thalamus and posterior limb of the internal capsule. Surgical resection was performed through a transpetrosal approach. Pathology resulted as malignant melanoma immunopositive for BRAF V600E mutation. Complete oncological workup revealed no other lesions; thus, he was diagnosed with PIMM of the brainstem.
Conclusion:
We report a rare case of primary pontine malignant melanoma in which microsurgical resection resulted in dramatic clinical improvement despite the challenging location. This is only the second reported case of brainstem PIMM. More patients with longer-term follow-up will be necessary to determine the best treatment approach.
Insights
Primary pontine malignant melanoma (PIMM) is exceptionally rare. This report details the second case of brainstem PIMM, highlighting successful surgical resection and the need for further research.
Area of Science:
- Neuro-oncology
- Neurosurgery
- Pathology
Background:
- Primary intracranial malignant melanomas (PIMMs) are rare, accounting for 1% of melanomas and 0.07% of intracranial tumors.
- PIMMs can occur in various intracranial locations, with only one prior report of a brainstem PIMM.
- This study presents the second documented case of primary pontine malignant melanoma and its management.
Observation:
- A 40-year-old male presented with hemiparesis, diplopia, and dysarthria.
- MRI revealed a hemorrhagic, enhancing lesion in the left pons with associated edema.
- The lesion was surgically resected via a transpetrosal approach.
Findings:
- Pathology confirmed malignant melanoma, immunopositive for BRAF V600E mutation.
- Comprehensive oncological workup excluded other metastatic sites, confirming a primary brainstem origin.
- The patient was diagnosed with primary pontine malignant melanoma.
Implications:
- Microsurgical resection led to significant clinical improvement in this rare case of brainstem PIMM.
- This case underscores the possibility of successful surgical intervention for PIMM in challenging locations.
- Further studies with larger patient cohorts and extended follow-up are essential to establish optimal treatment strategies for brainstem PIMMs.
