PMC7150700_01
(a) The tumor is hemorrhagic and composed of ramifying and intercommunicating vascular spaces with infiltration into adjacent thyroid tissue (Mag.100x). (b) Those tumor cells have large epithelioid and pleomorphic nuclei with clumped chromatin and prominent basophilic nucleoli, and abundant eosinophilic cytoplasm exhibiting occasional intracytoplasmic lumina with identifiable erythrocytes (Mag.400x). (c) Diffuse membranous and cytoplasmic immunoreactivity for CD31 (Mag.200x). (d) Faint and focal expression of CD34 (Mag.200x). (e) Diffuse nuclear staining for ERG (Mag.200x). (f) Faint and focal cytoplasmic immunoreactivity for Factor VIII-associated antigen (Mag.200x). (g) Negative staining for pancytokeratin in lesional cells (Mag.200x). (h) No expression for thyroglobulin (Mag.200x).
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fig1
Microscopically, the tumor was located beside blood clots and cell debris with infiltration into non-neoplastic thyroid tissue (Figure 1(a)) and fibrous pseudocapsule. Those tumor cells were large, harboring abundant eosinophilic cytoplasm and round, irregular and pleomorphic nuclei with clumped chromatin and prominent basophilic nucleoli (Figure 1(b)). Some cells exhibited intracytoplasmic lumina containing identifiable red blood cells (Figure 1(b)). Immunohistochemically, the tumor cells strongly and diffusely expressed CD31 (Figure 1(c)) and ERG (Figure 1(e)), but only faintly and focally stained by CD34 (Figure 1(d)) and Factor VIII-associated antigen (Figure 1(f)). All the epithelial markers, including CK (Figure 1(g)), EMA, and CAM5.2, and thyroglobulin (Figure 1(h)) were negative.