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Primary meningeal melanoma masquerading as neurofibromatosis type 2: illustrative case
Melanie Lang-Orsini1, Julian Wu2, Carl B Heilman2
1Departments of Pathology and Laboratory Medicine.
Background:
Primary meningeal melanocytic neoplasms are exceedingly rare tumors, representing only 0.06% to 0.1% of all primary brain tumors and ranging in spectrum from benign localized tumors to highly aggressive malignant lesions. The diagnosis of these tumors is often challenging from clinical, radiological, and pathologic standpoints. Equally challenging is the distinction between primary meningeal melanocytic neoplasm and metastatic melanoma.
Observations:
The authors reported the case of a 41-year-old man with imaging findings diagnostic of neurofibromatosis type 2: bilateral internal auditory canal lesions (most consistent with bilateral vestibular schwannomas), two dura-based lesions presumed to be meningiomas, multiple spinal lesions consistent with peripheral nerve sheath tumors, and one intramedullary spinal lesion consistent with an ependymoma. Biopsy of these lesions revealed melanocytic neoplasms with mild to moderate atypia and a mildly elevated proliferation index, which made the distinction between benign and malignant challenging. In addition, the disseminated nature of these tumors made it difficult to determinate whether they arose from the meninges or represented metastases from an occult primary melanoma.
Lessons:
This case illustrated the challenges presented by the diagnosis of meningeal melanocytic neoplasms and highlighted the importance of integrating the clinical and radiographic findings with histologic appearance and molecular studies.
Insights
Diagnosing rare primary meningeal melanocytic neoplasms is challenging. This case highlights the need to combine clinical, radiographic, and molecular data for accurate diagnosis and to differentiate from metastatic melanoma.
Area of Science:
- Neuro-oncology
- Dermatology
- Pathology
Background:
- Primary meningeal melanocytic neoplasms are rare brain tumors (0.06%-0.1%).
- These tumors present a diagnostic challenge, spanning benign to malignant lesions.
- Distinguishing them from metastatic melanoma is particularly difficult.
Observation:
- A 41-year-old man with neurofibromatosis type 2 presented with multiple lesions.
- Lesions included vestibular schwannomas, dura-based tumors, spinal nerve sheath tumors, and an ependymoma.
- Biopsies revealed melanocytic neoplasms with uncertain malignancy potential.
Findings:
- The case presented diagnostic challenges in classifying meningeal melanocytic neoplasms.
- Distinguishing between primary meningeal tumors and metastatic melanoma was complex.
- The disseminated nature of the tumors complicated the diagnostic pathway.
Implications:
- Accurate diagnosis requires integrating clinical, radiographic, and histological findings.
- Molecular studies are crucial for definitive classification.
- This case underscores the complexity of diagnosing and managing rare melanocytic neoplasms of the meninges.
