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

Figure 1 Imaging findings during initial admission. A and C: Thickening of the left epiglottis; B and D: Arytenoid and aryepiglottic fold; E: Osteolytic lesions of the left hyoid; F: Thyroid cartilage plate; G-I: ¹⁸F-FDG centered around the hyoid body and its left greater horn (SUV_max = 8.8), and left submandibular and submental soft tissue (SUV_max = 4.8) exhibited on positron emission tomography (PET); J-L: Computed tomography (CT); M-O: PET/CT fusion; and P: PET maximum-intensity projection image demonstrated no other sites with abnormal ¹⁸F-FDG uptake.

Figure 2 Histopathological and immunohistochemical analysis. A and B: Hematoxylin and eosin staining revealed angiofollicular lymph node hyperplasia (200 × and 400 ×); C and D: The presence of mature plasma cells (200 × and 400 ×); E-J: Positive immunohistochemical staining for plasma cell markers: CD138, CD38, κ light chains, λ light chains, CD79α, T-cell marker CD43; K: Negative staining for B-cell marker CD20; and L: The Ki-67 positive staining.

Figure 3 Molecular imaging in the evaluation of local recurrence and ectopic metastasis during follow-up. A-C: 99mTc-MDP radioactivity around the hyoid exhibited on single-photon emission computed tomography (SPECT), computed tomography (CT), and SPECT/CT fusion; D: Focal bone destruction and secondary hyperosteogeny exhibited on CT bone window; E and F: No evidence of distant bone metastasis on whole-body SPECT.