Published case study – First case of DLBCL presenting as bilateral internal auditory canal lesions and mimicking bilateral schwannomas

Last month, in a Letter to the Editor of the Canadian Journal of Neurological Sciences, Nevena Markovic from Western University London, Ontario, Canada, and colleagues reported a case of a male patient, 47 years of age, who was referred due to subacute unilateral hearing loss.

Key Highlights:

Clinical History:

• One-week history of disequilibrium and progressive left-sided hearing loss; not associated with headache, tinnitus, or vertigo
• Two days before assessment, patient experienced weakness of the right side of his face
• Vital signs were stable
• Cranial nerve examination revealed normal extraocular movements and visionary fields
• Unremarkable funduscopy, motor and somatosensory, and systemic examinations
• Blood cell count, chemistry, LDH, creatinine, and liver enzymes all within normal limits
• Negative for ESR, CRP, ENA, ANA, c-ANCA, and p-ANCA inflammatory/autoimmune markers
• Finger-to-nose and heel-to-shin tests were normal
• Bilateral mild lower motor neuron facial palsies, more prominent on the right
• Audiometry showed complete sensorineural hearing loss on the left
• Difficulties performing tandem gait
• MRI:
  • Bilateral Internal Auditory Canal (IAC) and cerebellopontine angle masses
  • Right measuring 14mm and left measuring 16mm in length
  • Images reported as bilateral cerebellopontine angle schwannomas
• Lumbar puncture identified elevated nucleated cells at 28×10⁶/L with 81% lymphoid predominance in the Cerebrospinal Fluid (CSF)
• Flow cytometry found monoclonal B-cell population accounting for approx. 3% of total leukocytes
• Cytology showed highly cellular aspirate containing a few atypical lymphocytes
• Bone marrow biopsy was not indicative of a B-cell lymphoproliferative neoplasm
• CT showed a round soft-tissue mass (3.5x3.8cm) abutting the right kidney
• CT-guided biopsy of the mass identified Diffuse Large B-Cell Lymphoma (DLBCL) pathology

Treatment and Outcome:

• Received six cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, methotrexate, and prednisone (R-CHOMP) with intrathecal methotrexate
• At 4-months (midway through chemotherapy):
  • CT identified significant improvement with only focal soft-tissue thickening remaining in the right perirenal space
  • MRI of brain found complete resolution of enhancement of bilateral IAC lesions
• At 6-months (chemotherapy completion), PET showed no evidence of hypermetabolic lesions to suggest ongoing disease
• At 2-years post-diagnosis, the patient continues to show no signs of clinical recurrence
• Hearing in the left ear improved to moderate loss on repeat audiology testing

The group state that, to their knowledge, this is the first published case of a DLBCL presenting as bilateral IAC lesions and mimicking bilateral schwannomas. The authors noted that this case responded well to R-CHOMP chemotherapy, with no evidence of recurrence after 2 years. They hypothesize the quick diagnosis from initiation of symptoms and rapid treatment initiation may have contributed to the excellent response.

Abstract:

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