THREE CASES OF SESSILE SERRATED LESIONS SHOWING PROLIFERATION OF PERINEURIOMA IN THE INTERSTITIUM SURROUNDING THE SERRATED GLANDULAR DUCT

Abstract

Perineurioma (PN), a benign tumor derived from perineurial cells, rarely occurs in the gastrointestinal tract. PN and a sessile serrated lesion (SSL) observed in a single tumor is extremely rare; the lesion that originated first remains unknown. We describe three lesions with SSL and concomitant PN within the same lesion. Histopathological evaluation of all three lesions showed interstitial spindle cell proliferation. Immunohistochemical analysis revealed cells with weak-to-strong immunopositivity for epithelial membrane antigen, glucose transporter-1, and Claudin-1. Therefore, we diagnosed PN in all three lesions. Of the three lesions, two measured 5 mm in size, and it was difficult to determine the lesion that had originated first. However, based on observation of a laterally spreading tumor lesion, PN was detected only in a small bulge. Further accumulation of these lesions is needed to elucidate the origin of PN accompanied by SSL.