Jugular Foramen Schwannoma Infiltrated by Rich Plasmacytes: Case Report of an Intracranial Tumor with Coexisting IGG4-Related Disease

Immunoglobulin G4-related disease (IgG4-related disease) is a recently described condition characterized by an inflammatory reaction that often presents as a mass lesion and can affect every organ system. We describe a unique case of IgG4-related disease, which was diagnosed in lower cranial nerve schwannoma tissue.

A 65-year-old woman presented with headache and nausea. Two days later, dysphagia and hoarseness developed and her condition rapidly deteriorated. An examination by an otolaryngologist revealed that she had left recurrent laryngeal nerve palsy and depressed activation of the swallowing reflexes. Magnetic resonance imaging (MRI) scans showed a heterogeneously enhancing dumbbell-shaped mass lesion with a maximum diameter of 3 cm in the left posterior fossa. There was no evidence of intratumoral hemorrhage. This tumor was both extra- and intracranial extension through the left enlarged jugular foramen. Two weeks after her initial symptoms, she was referred to our hospital. Her dysphagia and hoarseness had improved without treatment. Five weeks from her initial symptoms, she underwent surgery. However, at this time, she had few symptoms related to her lower cranial nerves, although the MRI findings of the tumor did not change. From the clinical point of view, her symptoms and clinical course, that is, a rapid presentation of relatively severe lower cranial nerve deficits considering the tumor size and spontaneous regression of the symptoms over several weeks, were not typical of those of lower cranial nerve schwannomas. We utilized an endoscopy-assisted retrosigmoid infralabyrinthine approach. First, we resected the intradural tumor via the retrosigmoid space under a microscope. We then drilled and widened the jugular foramen, and subsequently resected the intraforaminal tumor using an endoscope. We achieved subtotal resection of the tumor without any deterioration of the symptoms. The gross appearance of the tumor during surgery was consistent with that of a schwannoma. On rigorous pathologic review, the resected specimens exhibited apparent tumor tissue of the schwannoma accompanied by dense infiltration of plasmacytes. Immunohistochemical studies revealed that the proportion of IgG4-positive plasma cells relative to all IgG-positive cells was 57.5%. Hence, we diagnosed this tumor as a schwannoma accompanied by IgG4-related disease. Her whole-body computed tomography scan revealed no evidence of any other active disease. The serum level of IgG4 after the tumor resection was within normal limits. She was discharged without clinical symptoms.

We report the first case of jugular foramen schwannoma coexistent with histopathologically proven IgG4-related disease in the tumor. Furthermore, there are no similar reports on other intracranial tumors. Her unique clinical course of acute deterioration and subsequent spontaneous remission of dysphagia and hoarseness before surgery may be due to the inflammatory activity of the IgG4-related disease.