PMC6158946_01
CT sinuses (coronal view) for Case 1. There is contiguous opacification of the left maxillary sinus, nasal cavity, ethmoid air cells, and frontal sinus.
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A computed tomography (CT) scan of the sinuses showed abnormal soft tissue causing contiguous opacification of the left nasal cavity, frontal, maxillary and ethmoid sinuses (Figure 1).
Morphologic and immunohistochemical findings in Case 1. The tumor is composed of a mixture of back-to-back glands, anastomosing cords, and solid areas with squamoid morular metaplasia ((a) and (b), H&E, x100). Squamoid morular metaplasia is easily found ((c), H&E, x200). CK7 is positive in areas of glandular differentiation and negative in squamoid morules ((d), x200). CDX2 is positive in squamoid morules and negative in glandular areas ((e), x200). beta-catenin shows diffuse membranous staining throughout the tumor and nuclear staining restricted to squamoid morules ((f), x400).
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Microscopic examination revealed a low-grade sinonasal non-ITAC consisting of a mixture of back-to-back glands, anastomosing cords, and solid areas with squamoid morular metaplasia (Figures 2(a)-2(c), x100). CK7 in the areas of glandular morphology (Figure 2(d)), and they were negative for CK20, SOX10, CK5/6, p40, p63, and DOG1. CDX2 showed focal weak nuclear staining exclusively within the squamoid morules (Figure 2(e)), and beta-catenin likewise showed nuclear staining restricted to squamoid morules with membranous staining throughout the rest of the tumor (Figure 2(f)).
PMC6158946_02
CT sinuses (coronal) for Case 2. There is a 3 cm ovoid opacity in the mid to superior aspect of the right nasal cavity with extension to the roof of the nasal cavity.
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A CT scan of the sinuses revealed a 3.0 cm mass in the right nasal cavity extending to the roof of the nasal cavity, without an obvious cranial base defect (Figure 3).
Morphologic and immunohistochemical findings in Case 2. The tumor is composed of a tubulolobular proliferation of cuboidal cells with minimal cytologic atypia, and interspersed areas of squamoid morular metaplasia ((a), H&E, x100). Other areas of the tumor show more confluent squamoid metaplasia ((b), H&E, x200). CK7 positivity is restricted to glandular areas of the tumor ((c), x200). SOX10 is likewise positive in glandular areas and negative in squamoid areas ((d), x200). CDX2 shows an inverse staining pattern to CK7 and SOX10, with positivity restricted to squamoid areas ((e), x200). Nuclear accumulation of beta catenin is seen in squamoid areas ((f), x400).
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A biopsy was then performed, which revealed a proliferation of cytologically bland cuboidal cells forming crowded glandular structures, together with many squamoid morules as well as more confluent areas of squamoid metaplasia (Figures 4(a) and 4(b)). CK7 and SOX-10 in the glandular but not squamoid areas of the tumor (Figures 4(c) and 4(d)). CK20, CK5/6, and DOG1 were negative. Nuclear beta-catenin and CDX2 were strongly expressed in the areas of squamoid morular metaplasia (Figures 4(e) and 4(f)).