TY - JOUR
T1 - Papillary immature metaplasia of the anal canal
T2 - A low-grade lesion that can mimic a high-grade lesion
AU - Roberts, Jennifer M.
AU - Cornall, Alyssa M.
AU - Ekman, Deborah
AU - Law, Carmella
AU - Poynten, I. Mary
AU - Jin, Fengyi
AU - Hillman, Richard J.
AU - Templeton, David J.
AU - Tabrizi, Sepehr N.
AU - Garland, Suzanne M.
AU - Thurloe, Julia K.
AU - Grulich, Andrew E.
AU - Farnsworth, Annabelle
PY - 2016
Y1 - 2016
N2 - In a natural history study of anal human papillomavirus (HPV) infection and HPV-related lesions among homosexual men in Sydney, Australia, we identified 15 examples of papillary immature metaplasia (PIM) in anal biopsy samples. PIM has previously been described in the cervix, but not in the anal canal. PIM is a form of exophytic low-grade squamous intraepithelial lesion (eLSIL) also known as condyloma. In contrast to the maturing keratinocytes and koilocytosis seen in conventional eLSIL, the slender papillary structures of PIM have a surface population of immature squamous cells. In our anal samples PIM was characterized by close proximity to conventional eLSIL, was negative for p16INK4A (p16) expression, and revealed the presence of a single low-risk HPV genotype (either 6 or 11) in laser capture microdissected lesions. The clinical significance of recognizing PIM lies in preventing misdiagnosis as high-grade squamous intraepithelial lesion, (the presumed precursor to anal cancer), due to the morphologic immaturity of the cell population. In routine practice, awareness of anal canal PIM and p16 immunostaining will prevent this. Further study of the natural history of anal canal PIM is needed.
AB - In a natural history study of anal human papillomavirus (HPV) infection and HPV-related lesions among homosexual men in Sydney, Australia, we identified 15 examples of papillary immature metaplasia (PIM) in anal biopsy samples. PIM has previously been described in the cervix, but not in the anal canal. PIM is a form of exophytic low-grade squamous intraepithelial lesion (eLSIL) also known as condyloma. In contrast to the maturing keratinocytes and koilocytosis seen in conventional eLSIL, the slender papillary structures of PIM have a surface population of immature squamous cells. In our anal samples PIM was characterized by close proximity to conventional eLSIL, was negative for p16INK4A (p16) expression, and revealed the presence of a single low-risk HPV genotype (either 6 or 11) in laser capture microdissected lesions. The clinical significance of recognizing PIM lies in preventing misdiagnosis as high-grade squamous intraepithelial lesion, (the presumed precursor to anal cancer), due to the morphologic immaturity of the cell population. In routine practice, awareness of anal canal PIM and p16 immunostaining will prevent this. Further study of the natural history of anal canal PIM is needed.
KW - Anal canal
KW - High-grade squamous intraepithelial lesion (HSIL)
KW - Human papillomavirus (HPV)
KW - Lowgrade squamous intraepithelial lesion (LSIL)
KW - Papillary immature metaplasia
UR - http://www.scopus.com/inward/record.url?scp=84959162770&partnerID=8YFLogxK
U2 - 10.1097/PAS.0000000000000549
DO - 10.1097/PAS.0000000000000549
M3 - Article
C2 - 26551619
AN - SCOPUS:84959162770
SN - 0147-5185
VL - 40
SP - 348
EP - 353
JO - American Journal of Surgical Pathology
JF - American Journal of Surgical Pathology
IS - 3
ER -