Skull Base Plasmacytomas: Surgical Approach and Review of Management

Introduction: Solitary plasmacytomas of the skull base are a rare entity. Patients with these abnormalities can present with intracranial extension and extensive skull base involvement, often resulting in cranial neuropathies and mass effect. Treatment of these rare lesions is not well defined.

Methods: We retrospectively reviewed the records of patients with calvarial plasmacytomas treated at the University of Michigan. Records were reviewed for symptoms, presentation, treatment, as well as long-term prognosis. Radiographic images were reviewed for extent of involvement and changes over time.

Results: Six patients presented with skull base and calvarial plasmacytomas. Three patients presented with intracranial extension, one of which had significant mass effect with midline shift. Four patients were found to have true skull base lesions, and two were found to have frontal sinus lesions. Overall, four patients were found to have systemic plasma cell disease shortly after presentation. Of the four patients with skull base lesions, three were diagnosed with systemic plasma cell disease shortly after presentation. In terms of location, two patients presented with large clival lesions with extension into the occipital condyle. One of these presented with a large lesion extending from the clivus to the occipital condyle, with involvement of skull base foramina, and underwent an expanded endonasal approach for subtotal resection followed by radiation. The other patient who presented with a clival lesion also extending into the condyle had evidence of occipitocervical instability; this patient underwent debulking with occipitocervical fusion. One patient presented with a sphenoid sinus mass with clival extension. He underwent an endoscopic biopsy. He was found to have extensive systemic disease and died within 6 months of diagnosis. One patient presented with multiple skull base lytic lesions with diffuse systemic disease. This patient had a large intracranial mass with mass effect and midline shift. Given his diffuse systemic disease, the patient opted for nonoperative management. This patient underwent chemotherapy, radiation, and stem cell therapy and has been followed for 3.6 years thus far. He continues to have significant intracranial mass effect. Two patients presented with frontal sinus lesions with intracranial extension, one of which underwent a bifrontal craniotomy with gross total resection. The other patient was recently diagnosed and management is pending. The mean follow-up time of the five patients who have received treatment is 1.92 years with four out of five patients surviving at last follow-up.

Conclusions: Although plasmacytomas are radiosensitive, surgery still has an important role in the treatment of patients with skull base and intracranial disease. As the efficacy and morbidity of skull base approaches improves, surgery may play a greater role in the treatment of these lesions. Patients with skull base plasmacytomas appear to have a high likelihood of developing systemic plasma cell disease.