SMILE-like lesion in the anal canal

ABSTRACT

Stratified mucin-producing intraepithelial lesion (SMILE) is an intraepithelial lesion with overlapping features of the high-grade squamous intraepithelial lesion (HSIL) and adenocarcinoma in situ (AIS). Currently, it is well described in the cervix. We present a case showing similar SMILE-like lesions in the polypectomy specimen from the anal canal along with invasive adenocarcinoma components. This lesion showed an immuno-profile characteristic of a SMILE lesion described in the cervix, such as p63 negativity, high ki67 index, and nuclear positivity for p16. It might be arising from the Human papillomavirus prone transitional region of the anal canal as described in the cervix. However, we could not assure this association and etiological link due to insufficient material in the formalin-fixed paraffin-embedded block. Notwithstanding, we strongly suggest that the HPV is the main driver for this SMILE-like lesion similar to what is described in the cervix. To our knowledge, this is the first case report of a SMILE lesion in the anal canal. Further studies will be required to elucidate the underlying pathogenetic mechanism of SMILE-like lesions described in the anal canal.

Keywords
Anal canal; Adenocarcinoma; Polyp; Carcinoma in Situ