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

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.

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.

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.

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.