Intraepithelially entrapped blood vessels in oral carcinoma in-situ.

It can be difficult to make a certain diagnosis in case of an oral borderline malignant lesion on hematoxylin-eosin-stained sections only. Furthermore, assessment of surgical margins of borderline lesions is difficult with the naked eye. We set out to determine the topographical distribution of capillary blood vessels within the epithelial zone and to assess its use as an aid for histopathological diagnosis and a framework for clinical assessment of lesional margins using optical techniques, such as narrow-band imaging (NBI) endoscopy. Capillary blood vessels entrapped in the epithelial compartment, which we have designated as intraepithelially entrapped blood vessels (IEBVs), were examined for their frequency, location, and shape in normal mucosa, dysplasia, and carcinoma in-situ (CIS) of the tongue using immunohistochemistry for CD31 and type IV collagen. When counted per unit length of epithelial surface, IEBVs increased in number significantly in CIS (5.6 ± 2.8), which was two times more than in normal (1.9 ± 1.6) and dysplastic (2.4 ± 1.5) epithelia. In addition, IEBVs in CIS had compressed shapes with occasional obstruction or collapse with hemorrhage and were arranged perpendicular to and extending up to the epithelial surface. These characteristic IEBVs in CIS were considered to be generated by complex expansion of rete ridges due to carcinoma cell proliferation within the limited epithelial space determined by the basement membrane. The recognition of IEBVs was helpful in the differential diagnosis of oral CIS, and the present data provide a valuable frame of reference for detecting oral CIS areas using such NBI-based optical devices.