Solitary bone plasmacytoma of the axis, a rare and challenging case with good outcomes

Abstract

Introduction: Plasmacytoma is a rare hematological malignancy with a more favorable prognosis than multiple myeloma. This case report focuses on a unique solitary bone plasmacytoma (SBP) at the craniovertebral junction (CVJ), managed through surgery and radiotherapy.

Case presentation: A 50-year-old patient presented with four months of worsening neck pain and cervicobrachial neuralgia. Despite treatment and physiotherapy, symptoms persisted. Clinical examination revealed neck stiffness, with no motor or sensory deficits. Radiographs and MRI showed an infiltrating axis lesion without instability signs. A CT-guided biopsy yielded inconclusive results. To address instability and establish a diagnosis, a curettage biopsy of the C2 posterior arch was performed, followed by occipito-C4 fusion using an iliac crest graft. Histological examination confirmed SBP. Adjuvant radiotherapy and chemotherapy were administered. At four-year follow-up, there was no multiple myeloma progression, but limited neck mobility were reported, with stable fusion observed on imaging.

Discussion: Solitary bone plasmacytoma primarily affects the axial skeleton, with rare upper cervical spine involvement. Diagnostic criteria include histological confirmation, normal bone marrow analysis, unremarkable imaging (except for the primary lesion), and absence of end-organ damage related to lymphoplasmacytic proliferative disorders. Clinical presentation is nonspecific, and MRI is valuable for soft tissue assessment. Radiotherapy is the primary treatment, with surgery reserved for specific indications.

Conclusion: Solitary bone plasmacytoma is a rare condition with a favorable prognosis when promptly managed. This case underscores the importance of early diagnosis and treatment to prevent recurrence or multiple myeloma progression. A multidisciplinary approach, including surgery when necessary, is crucial for optimal outcomes.

Keywords: Case report; Cervical spine; Plasmocytoma.

Fig. 1

A lateral cervical spine radiograph with an open mouth view shows osteolysis of the odontoid process of the axis without signs of occipitocervical instability.

Fig. 2

CT scan appearance of a lytic lesion in the axis without detectable instability at the occipitocervical junction.

Fig. 3

MRI images showing an infiltrative process involving the axis vertebral body, as well as the odontoid process, with invasion of the right side of the posterior arch and extension into the soft tissues.

Fig. 4

Intraoperative appearance and postoperative imaging following curettage biopsy of the posterior arch of C2 with instrumented occipito-C4 fusion using a posterior iliac graft.

Fig. 5

Radiological assessment at the latest follow-up demonstrates a solid fusion without signs of tumor recurrence.