PMC5824517_01
Extraoral well-defined swelling on the left mid-face region
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F1
The swelling was initially small in size measuring around 3 cm, which then gradually increased to the present size [Figure 1].
Intraorally, well-defined, sessile swelling on the left side of the palate.
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F2
There was grade II mobility with respect to 27 and 28 [Figure 2].
Computed tomography scan showing three-dimensional view of the extent of the lesion, revealing large destructive lesion involving maxillary sinus and maxilla on the left side
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F3
There was partial destruction of nasal septum and destruction of pterygoid plate on the left side [Figure 3].
Magnetic resonance imaging scans showing the extent of the lesion, involving the floor of the left orbit and maxillary bone
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F4
The left orbital cavity was compromised with normal intraorbital contents [Figure 4].
(a) Microscopic examination of H&E stained lesional tissue (low magnification) lesion devoid of epithelium, showing densely packed cells throughout the tissue with focal areas of hemorrhage. (b) higher magnification showing monotonous sheets of round cells densely packed throughout the lesional tissue
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F5
The lesional connective tissue showed hypo- and hyper-cellular areas, [Figure 5a] intralesional hemorrhage and necrotic areas, with some pleomorphic, hyperchromatic and monomorphous round cells. Perivascular hyalinization along with extensive vascularity with hemangiopericytoma like areas was also seen [Figure 5b].
Periodic acid-Schiff stained section showing intracytoplasmic glycogen positivity
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F6
The present case was also positive for intracytoplasmic glycogen with periodic acid-Schiff (PAS) reagent [Figure 6].
Lesional tissue expressing strong CD99 positivity
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F7
The neoplastic cells were positive for CD99 [Figure 7], FLI-1, Vimentin [Figure 8] and were negative for cytokeratin smooth muscle actin, muscle-specific actin, Desmin, B-Catenin, Calponin, CD31, epithelial membrane antigen (EMA), S100, synaptophysin, chromogranin, glial fibrillary acidic protein (GFAP) and CD56.
Lesional tissue expressing strong positivity for Vimentin
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F8
The neoplastic cells were positive for CD99 [Figure 7], FLI-1, Vimentin [Figure 8] and were negative for cytokeratin smooth muscle actin, muscle-specific actin, Desmin, B-Catenin, Calponin, CD31, epithelial membrane antigen (EMA), S100, synaptophysin, chromogranin, glial fibrillary acidic protein (GFAP) and CD56.