Acute Intratumoral Hemorrhage: A Rare Presentation of Melanotic Schwannoma

Introduction: Melanotic schwannoma (MSc) is a rare melanin-producing variant of nerve sheath tumors that uncommonly occurs in the cerebellopontine angle (CPA). Intratumoral hemorrhage (ITH) as a feature of MSc is often subacute and has not been reported to cause clinically significant hemorrhage. In this study, we report a unique case of CPA MSc presenting with acute neurological deterioration due to clinically significant ITH.

Case History: Our patient was a 71-year-old male who presented with a month of headaches, and two weeks of progressive ataxia, and hearing loss. MRI on admission revealed a 2.5 cm × 2.4 cm well-circumscribed, T1 hyperintense, T2 hypointense, and heterogeneously enhancing left CPA mass with internal cystic changes and hemorrhage. The mass was initially thought to be an IX, X, and XI cranial nerves complex schwannoma.

On admission day 2, the patient acutely deteriorated with left facial droop, numbness, and slurred speech. CT showed increased ITH with hemorrhagic extension into the subarachnoid spaces and ventricles causing mass effect on the brain stem, hydrocephalus, and transtentorial herniation. An emergent left retrosigmoid craniectomy with tumor debulking was performed. The final pathology showed spindled tumor cells with extensive pigments, and the immunostain results were consistent with MSc. The patient developed subsequent complications including brainstem hemorrhages and left cerebellar infarct. He expired after a brief stay in the intensive care unit.

Discussion: MSc is an unencapsulated tumor with spindled Schwann's cells containing melanin that is thought to result from melanomatous transformation of neoplastic Schwann cells. Due to its melanin-producing ability, MSc is often T1-hyperintense and T2-hypointense on MRI as opposed to the typical T1 hypointense and T2 hyperintense patterns of schwannoma. The presence of subacute ITH, however, can cause difficulty in making a prospective diagnosis on imaging.

Complications of intracranial MSc include nerve damage, subacute hemorrhage, and sequelae from metastasis. Resection is often recommended due to symptoms, and its malignant potential which has been reported to be as high as 42%. Acute decompensation due to clinically significant ITH in intracranial MSc has not been previously reported as a potential complication. Within the family of schwannoma, the more prevalent vestibular schwannoma rarely presents with clinically significant ITH, and such occurrence is often linked to rapid growth, high tumor vascularization, and a large size of more than 25 mm. Clinically, significant ITH in MSc is not well recognized but is likely due to similar risk factors and mechanisms.

To the best of our knowledge, this is the only reported case in the literature of intracranial MSc presenting with acute massive ITH leading to rapid neurological deterioration and fatality.

Publication History

Article published online:
12 February 2021