Diagnostic challenge: A case of extramedullary plasmacytoma of thyroid primary associated with literature review

Abstract

Background

Plasmacytoma comprises diseases originating from B lymphocytes and characterized by the neoplastic proliferation of monoclonal plasma cells. Among these, extramedullary plasmacytoma is a rare tumor of plasma cell primary to bone marrow hematopoietic tissue, accounting for approximately 4 % of all plasmacytomas, and exceptionally rare in the thyroid gland. Due to its rarity, early diagnosis and treatment are critical for patients, making current diagnosis and treatment approaches extremely challenging.

Case introduction

A 75-year-old female was hospitalized after “finding a thyroid nodule in January.” Cervical color ultrasound revealed a 4a-sized tumor in the right thyroid. The preliminary diagnosis by clinicians revealed a thyroid undifferentiated carcinoma. Following admission, a thyroid puncture biopsy of the right lobe, combined with characteristic morphology and immunohistochemistry, confirmed the final pathological diagnosis was thyroid plasmacytoma. The patient was discharged with regular chemoradiation and underwent 15 months of follow-up without recurrence.

Conclusion

Thyroid primary plasma fine tumor presents without characteristic clinical manifestations. Clinicians may face challenges in diagnosing it due to nonspecific symptoms and imaging findings. This paper reports a rare case of primary thyroid plasmacytoma, offering valuable insights for clinicians in diagnosing and treating this condition.