PMC4663298_01
CT orbits: coronal section showing a well-defined heterogeneous lesion protruding into the middle meatus and right orbit.
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CT sinuses: axial section showing the lesion within the right nasolacrimal duct with evidence of bony remodelling.
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Endoscopic view demonstrating a pale, polypoid-like mass, covered by a papillary surface, protruding from the middle meatus.
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Resonance Imaging (MRI) of the head confirmed a mass arising from the proximal NLD, mildly hypointense on T2 weighted images, isointense on T1 weighted images, and avidly enhancing on postcontrast images eroding the anterior lamina papyracea and bulging into the medial aspect of the right orbit. Right nasal bones were eroded with the mass extending into the nasal cavity to lie in the middle meatus anteriorly (Figure 3).
(a) Hyperplastic squamous epithelium growing endophytically. The inverted papilloma is seen to arise from nasolacrimal duct epithelium (arrow). Haematoxylin and Eosin, 20x. (b) Foci of atypia amounting to moderate dysplasia. No invasive malignancy is seen. Haematoxylin and Eosin, 40x. (c) Inverted pattern of growth. Haematoxylin and Eosin, 20x. (d) Immunohistochemistry for P16 showing block positivity. P16 IHC Syntech antibody, 20x.
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Histological examination revealed hyperplastic ribbons of basement membrane-enclosed epithelium growing endophytically into the underlying stroma (Figures 4(a) and 4(c)). Multiple foci of atypia, interpreted as moderate dysplasia, were reported with no overall evidence of invasive malignancy (Figure 4(b)). Immunohistochemistry was positive for p16 (Figure 4(d)).