Anal papillary immature metaplasia: the LSIL which mimics HSIL

Jennifer M. Roberts, Deborah Ekman, Alyssa M. Cornall, Carmella Law, Sepehr N. Tabrizi, Suzanne M. Garland, Fengyi Jin, Isobel Mary Poynten, Richard Hillman, David Templeton, Christopher Fairley, Julia Thurloe, Andrew Grulich, Annabelle Farnsworth

Research output: Contribution to journalMeeting abstractpeer-review


Background: Papillary immature metaplasia (PIM) has been well-described in the cervix, as a form of low-grade intraepithelial lesion (LSIL), which can cause diagnostic confusion with high-grade intraepithelial lesion (HSIL), both cytologically and histologically. However, PIM has not previously been specifically described in the anal canal.

Methods: In the Study of the Prevention of Anal Cancer (SPANC), a natural history study of human papillomavirus (HPV) infection and related lesions of the anal canal in homosexual men, we identifi ed examples of PIM in high-resolution anoscopy-guided biopsies. Clinical, morphological and molecular features are described.

Results: Of 482 men recruited to end 2014, 11 examples of PIM were identified in biopsies from 9 men (4 HIV positive), aged 40–61 years. Each PIM lesion had characteristic histological features of slender papillae covered by a multilayer of immature squamous cells. Variable degrees of nuclear atypia were present and the differential diagnosis included HSIL in 4 cases. Immunostaining for p16 was negative in each PIM lesion, thus excluding HSIL. In each biopsy, there was adjacent or admixed typical exophytic LSIL. Histologic HSIL was found in the same octant of the anal canal in 1 case and in a different octant in 5. HPV typing on 9 tissue samples following laser capture microdissection revealed the PIM-associated genotype to be HPV 6 in 5 cases and HPV 11 in 4.

Conclusions: Like its cervical counterpart, anal PIM is a form of LSIL, associated with low-risk HPV types. Increased awareness of this entity may prevent misdiagnosis as HSIL.
Original languageEnglish
Article number26
Pages (from-to)88-89
Number of pages2
JournalSexual Health
Issue number1
Publication statusPublished - 2015
Externally publishedYes
EventInternational Anal Neoplasia Society Scientific Meeting: The Second Interdisciplinary Forum on Anal Neoplasia - Atlanta, United States
Duration: 13 Mar 201515 Mar 2015


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