PMC5165139_01
CT scans of the patient. (a) Sagittal view of head and neck. (b, c) Axial views.
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CT of the head and neck showed that the lesion had a wide base and a diameter of about 3 cm, occupying almost all the oropharynx (Figures 1(a) and 1(b)); foci of calcium deposits were also seen (Figure 1(c)).
Peripheral part of the tumor. (a) Necrotic surface of the polypoid neoformation (40x). (b) Hyperplastic residual squamous epithelium (40x). (c) Atypical spindle and globoid elements beneath the necrotic area (100x). (d) Atypical elements in alveolar aggregation (100x).
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The peripheral area consisted of necrotic inflammatory tissue (Figure 2(a)) on which only short sections of residual squamous surface epithelium were recognizable (Figure 2(b)). Within the necrotic outer layer, a brisk microangiogenesis by granulation tissue is present, which is intermingled groups of plump, spindled, or globoid cells, with hyperchromatic and irregular nuclei, sometimes with atypical mitosis, and aggregates in a pseudoalveolar fashion (Figures 2(c) and 2(d)).
Core of the tumor. (a) Monomorphic proliferation of spindle elements (40x). (b) Myoid morphology (100x). (c) Osteoid trabeculae. (d) Mature trabecular bone.
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The core of the lesion consisted of a proliferation of spindled, myoid-like elements, assembled in interwoven bundles, with voluminous, oval, hyperchromatic nuclei (Figures 3(a) and 3(b)). In the context of the spindled proliferation, we observed trabeculae of osteoid matrix with some areas of calcified cancellous bone (Figures 3(c) and 3(d)).
Immunohistochemistry. (a) Intense positivity for cytokeratin (clone AE1-AE3) of atypical elements in subepithelial site (40x). (b) Total negativity for cytokeratin (clone AE1-AE3) in the spindle elements of the core. (c) Vimentin positivity in the spindle component. (d) alpha-Smooth muscle actin positivity.
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Immunohistochemical analysis (Table 1) highlighted positivity for cytokeratins (Figure 4(a)), epithelial membrane antigen, and P63, with varying intensity and frequency, in the atypical elements present in the superficial necrotic tissue, but not in the spindled core (Figure 4(b)). The spindled core expressed, with varying intensity and frequency, vimentin (Figure 4(c)), smooth muscle actin (Figure 4(d)), calponin, CD99 (Figure 5(a)), and BCL2 (focal).
Immunohistochemistry. (a) Intense and diffuse positivity for CD99 in the spindle elements. (b) Ki-67 positivity in the spindle elements. (c) Positivity for CD34 in the superficial granulation tissue. (d) Positivity for CD34 in the core.
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The spindled core expressed, with varying intensity and frequency, vimentin (Figure 4(c)), smooth muscle actin (Figure 4(d)), calponin, CD99 (Figure 5(a)), and BCL2 (focal). Staining for Ki-67 revealed a rather high proliferation index (35%) in atypical elements expressing cytokeratins (Figure 5(b)). Staining for CD34 indicated rich microangiogenesis in the granulation tissue of the superficial necrotic band, but a paucity of vascular proliferation in the deeper area (Figures 5(c) and 5(d)).