Chronic Lymphocytic Leukemia Presenting as a Tumor of the Internal Auditory Canal

Background: The differential diagnosis of an enhancing lesion in the internal auditory canal (IAC) is broad. While the great majority of IAC tumors are vestibular schwannomas (VS), other tumors such as meningiomas, metastases, and even hematologic malignancies can occur here. In addition, many non-neoplastic inflammatory pathologies can cause IAC nodular enhancement.

Methods: This study is a case report.

Results: A 64-year-old, right-handed man presented with a vague 4-year history of progressive right-sided hearing loss and a 6- to 8-week history of intermittent hemifacial spasms. His medical history is significant for smoking three-fourths of a pack of cigarettes daily since the age of 50 years and losing 20 pounds unintentionally over the 2 years before his presentation. He also complained of bilateral tinnitus and mild gait imbalance. His hearing loss progressed to near complete right-sided deafness resulting in evaluation by a local physician. An audiogram showed no word recognition and inability to hear above 750 Hz on the right in September 2013.The left side was largely unremarkable. He did not undergo further testing at that time. His hearing continued to worsen and he started having intermittent spams of the right side of his face consistent with hemifacial spasm. An MRI in July 2014 showed linear and nodular enhancement of the nerves in the IAC on the right side. The patient was referred to our institution with the diagnosis of right VS. His neurological examination showed no focal deficits besides his known right-sided hearing loss. It was noted; however, on the sagittal T1 MRI that he had diffused cervical adenopathy. CT imaging of the head and neck was done to further investigate this confirmed diffuse adenopathy worrisome for hematologic malignancy. A complete blood count (CBC) showed a white blood cell count of 187,000/µL. An ultrasound-guided biopsy of a left submandibular lymph node showed a monomorphic population of small lymphocytes. Flow cytometry of the peripheral blood showed a lambda restricted monoclonal protein that coexpressed CD5, CD 19, CD20, CD 23, and CD 38. The cells were ZAP 70 and CD4 positive. A bone marrow biopsy confirmed the diagnosis. The patient underwent further staging and screening for his new diagnosis of chronic lymphocytic leukemia (CLL).

Conclusion: While the great majority of IAC masses represent VS, a judicial work-up of patients with atypical clinical and/or imaging presentations should be undertaken to investigate other possibilities. CLL can very rarely present within the central nervous system causing cranial nerve findings.