Dysplasia of the Anus
Differential Diagnosis
| Anus high grade squamous intraepithelial lesion (HSIL) | Anus reactive atypia |
| Strong band-like staining for p16 | At most patchy or weak staining for p16 |
| Pagetoid Squamous Cell Carcinoma In Situ / HSIL | Extramammary Paget Disease |
| Atypical cells usually merge with surrounding keratinocytes | Discrete population of atypical cells |
| Atypical cells may keratinize | Atypical cells may form lumens or be mucin positive |
| Desmosomes and keratohyaline granules may be visible in atypical cells | Desmosomes and keratohyaline granules not present |
| HMWCK+, p63+, CK7 neg, BerEp4 neg | CK7 >90%+, p63 & HMWCK neg (positive if underlying urothelial carcinoma), BerEp4+ |
| GCDFP15 neg | GCDFP15 positive if primary, variable if secondary |
| Anus high grade squamous intraepithelial lesion (HSIL) | Bowenoid Papulosis |
| Usually a solitary enlarging plaque or found within a condyloma acuminatum | Multiple small (2-10 mm) plaques |
| Does not spontaneously regress | Lesions come and go spontaneously |
| Frequently develops invasive carcinoma | Infrequent development of invasive carcinoma (may be increased in HIV patients) |
Both associated with HPV 16
Distinction is made on clinical grounds
- Condyloma with podophyllin effect should be distinguished from HSIL
- Podophyllin does not produce:
- Cytologic dysplasia
- Disturbance of maturation
- Dyskeratosis
- Early podophyllin effects (≤48 hours post application)
- Intra- and intercellular edema
- Necrotic keratinocytes in lower half of epithelium
- Numerous mitotic figures in lower half of epithelium
- Changes resolving by 72 hours
- Necrotic keratinocytes now in upper half of epithelium
- Fewer mitotic figures
- Changes entirely resolved by one week
