PMC2763065_01
A (Case 1) - A sessile nodule covered by filiform and erythematous fungiform papillae, located on the lingual apex. B (Case 2) - A small pediculadum nodule in the lower lip (black arrow)
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Oral examination revealed a pediculadum nodule measuring 0.5 cm in diameter in the lower lip (Figure 1B).
PMC2763065_02
A (Case 1) - A sessile nodule covered by filiform and erythematous fungiform papillae, located on the lingual apex. B (Case 2) - A small pediculadum nodule in the lower lip (black arrow)
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Oral examination revealed a pediculadum nodule measuring 0.5 cm in diameter in the lower lip (Figure 1B).
(Case 1) - Tortuous and well-circumscribed cellular proliferation of peripheral nerve boundaries (H&E, original magnification x25)
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Hematoxylin and eosin (H&E) sections of both cases showed circumscribed lesions surrounded by fibrous connective tissue composed of layers of spindle-shaped cells around a central axon, forming structures described as onion-bulb-like (Figures 2 and 3A).
A - Onion-bulb-like structures composed of central Schwann cells and axons surrounded by circumferential proliferation of spindle-shaped perineurial neoplastic cells (hematoxylin and eosin, original magnification x200). B - Perineurial cells immunoreactive for epithelial membrane antigen encircle negative Schwann cells and axons (original magnification x200). C - Immunoexpression of S-100 protein in the myelin sheath and Schwann cells, surrounded by perineurial cells that were negative for S-100 protein(original magnification x200)
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Hematoxylin and eosin (H&E) sections of both cases showed circumscribed lesions surrounded by fibrous connective tissue composed of layers of spindle-shaped cells around a central axon, forming structures described as onion-bulb-like (Figures 2 and 3A). The perineurial cells showed strong immunoreactivity for EMA (Figure 3B) (E29 clone; Dakocytomation, Denmark A/S; dilution 1:400), while the Schwann cells were positive for S100 protein (Figure 3C) (Sigma-Aldrich, St Lois, MO; dilution 1:10,000).
(Case 1) - Scanning electron micrograph showing onion-bulb-like structures. (x600)
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The scanning electron micrograph of IP was only illustrative (Figure 4) in case 1, but this technique can also be useful to confirm the diagnosis of perineurioma.