PMC4451648_01
(a) Clinical examination: Small nodule behind the left ear. Cytological smears showing (b) basaloid cells in nests sheets and trabeculae (PAP stain; x100). (c) peripheral palisading of cells (red arrows) and bare nuclei in background (PAP, x400)); (d) basement membrane material around cell clusters (green arrows) (PAP, x400)
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F1
Clinical examination showed a nodule behind the left ear measuring 1.5 x 1.5 cm in size [Figure 1a]. Squamous morules, hyaline globules, stromal elements, inflammatory cells, pleomorphism, mitoses and necrosis were absent [Figure 1b-d].
(a) Gross examination: Tumor with a solid homogenous grey-white lobulated cut surface. (b-d) Histological sections showing basaloid cells with uniform round-oval nuclei, eosinophilic cytoplasm and indistinct cytoplasmic borders arranged in tubulo-trabecular pattern separated by collagenous stroma and peripheral palisading within the nests. (H&E stain, (b) x200, (c) x400, (d) x400)
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F2
The surgical specimen consisted of a nodular, well encapsulated, solid tumor measuring 2 x 1.5 cm with a homogenous lobulated cut surface [Figure 2a]. Peripheral palisading of cuboidal cells was observed in occasional tumor nests [Figure 2b and c].