Solitary hyoid plasmacytoma with unicentric Castleman disease: A case report and review of literature

BACKGROUND: Solitary plasmacytoma and unicentric Castleman disease (UCD) are rare lymphoproliferative disorders characterized by monoclonal plasma cells and a single set of locally enlarged lymph nodes, respectively. CASE SUMMARY: A 48-year-old Han Chinese man presented to our department with a neck mass and progressive foreign body sensation in his throat. (18)F-FDG positron emission tomography revealed focally increased radioactivity centered around the hyoid, and computed tomography (CT) revealed osteolytic lesions. Histopathology revealed Castleman-like features and CD138/CD38-positive mature plasma cells. Systemic work-up ruled out the possibility of POEMS syndrome, lymphoma, and multiple myeloma, leading to a final diagnosis of solitary hyoid plasmacytoma with UCD. The patient underwent partial hyoid resection and selective neck dissection, followed by intensity-modulated radiotherapy. 99mTc-MDP single-photon emission computed tomography/CT reevaluation showed neither local recurrence nor distant bone metastasis at the 40-mo follow-up. CONCLUSION: The diagnostic process and differential diagnosis of this rare case provided valuable educational information to clinicians.