De Novo Extramedullary Plasmacytoma of Thyroid Cartilage.

Myeloma involving the laryngeal cartilage is rare, whereas extramedullary plasmacytoma involving only the thyroid cartilage is even rarer. No case of de novo extramedullary plasmacytoma involving thyroid cartilage has been published so far. Hence, it was a diagnostic challenge for clinicians, radiologists, and pathologists. Here, we presented a case of a 61-year-old man who had fixed right laryngeal swelling. After 18 F-FDG PET/CT, biopsy, and myeloma workup, it was found to be plasmacytoma involving the right thyroid cartilage lamina. This case highlighted the rarity of this presentation and the importance of keeping in mind this differential to lead toward diagnosis.