Skull base plasmacytoma: A unique case of POEMS syndrome with a plasmacytoma causing craniocervical instability

Introduction Plasmacytomas, considered to be the solitary counterparts of multiple myeloma, are neoplastic monoclonal plasma cell proliferations within soft tissue or bone. Plasmacytomas often present as a collection of findings known as POEMS-syndrome (Polyneuropathy, Organomegaly, Endocrinopathy, M-Protein spike, and Skin changes). Case description We present a report of a 47 yo male diagnosed with POEMS-syndrome secondary to a skull base plasmacytoma. The mass resulted in marked instability of the cranio-cervical junction due to bony erosion. Following an induction course of chemotherapy, he showed clinical improvement with a marked reduction in tumor size and underwent an autologous peripheral blood stem cell transplant for systemic treatment of his POEMS-syndrome. Following completion of systemic treatment, he then underwent a definitive occipital-cervical fusion without complications. His neurologic exam upon dismissal was stable with subjective improvement in left upper extremity strength. Postoperative radiographs confirmed spinal alignment and pathological examination of a small biopsy from C1 revealed benign fibrous tissue. Conclusion To the best of our knowledge, this is the first report of a skull-base plasmacytoma associated with POEMS-syndrome, causing cranio-cervical instability. The approach of systemic therapy combined with temporary external fixation, followed by definitive occipital cervical fusion resulted in a good outcome for this patient.