Atypia / premalignant / preinvasive lesions
LSIL / CIN I / low grade dysplasia

Author: Marilin Rosa, M.D. (see Authors page)

Revised: 14 April 2017, last major update June 2011

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed search: LSIL / CIN I / low grade dysplasia

Cite this page: LSIL / CIN I / low grade dysplasia. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/cervixcytologyLSIL.html. Accessed August 18th, 2017.
  • Low grade squamous intraepithelial neoplasia (LSIL) encompasses HPV changes and cervical intraepithelial neoplasia I (CINI)
  • Previously called mild dysplasia
Clinical features
  • Cases with few abnormal cells are more likely to be missed (Arch Pathol Lab Med 2005;129:23)
  • HPV negative LSIL is not a distinct biologic entity; often due to false positive LSIL or false negative HPV; HPV tests are designed to detect high risk HPV, not the low risk HPV that cause LSIL (Cancer 2005;105:253)
  • HPV16+ LSIL or ASC have higher risk for HSIL than HPV16 negative LSIL / ASC (J Natl Cancer Inst 2005;97:1066)
  • Most LSIL cases during pregnancy remain stable or regress but most HSIL cases diagnosed antepartum persist postpartum and 11% progress to invasive carcinoma (Cancer 2004;102:228)
  • LSIL diagnostic accuracy is improved by Ki67 staining
Cytology description
  • Enlarged nuclei at least 3 × size of nucleus of intermediate cell but N/C ratio is less than 1/3 Hyperchromasia (nuclei darker than that of intermediate cell), cell may be enlarged (largest atypical cells in gynecologic cytology are LSIL), slight increase in N/C ratio
  • No nucleoli
  • Binucleation is more common than multi nucleation
  • Koilocytes may be present and exhibit nuclear pleomorphism, wrinkled nuclei, hyperchromasia, binucleation, perinuclear halos with distinct clear zone around nucleus and condensation of denser cytoplasm around the periphery
  • Cytology from immature LSIL may be interpreted as metaplasia, ASCUS or HSIL
  • Few / no mitotic figures, particularly in lower half of epithelium; no atypical mitotic figures
Cytology images

Images hosted on other servers:

Various images

Contributed by: Marilin Rosa M.D, University of Florida

Differential diagnosis
  • HSIL
  • Postmenopausal squamous atypia: pseudokoilocytosis with uniform / round halos with central nuclei, slightly hyperchromatic, occasional grooves, occasional binucleation; is associated with urothelial metaplasia and atrophy; is NOT associated with HPV (Mod Pathol 1995;8:408)
  • Reactive epithelial changes: cytoplasmic halos are associated with glycogenated cells, mild atypia is associated with inflammation but no pleomorphism is present; small binucleated cells may be seen in a background of metaplasia; reactive changes usually have regular nuclear spacing, distinct nucleoli, no nuclear atypia in upper layers, superficial maturation