Cancer Cytology: Descriptions
Negative for Intraepithelial Lesion or Malignancy (NILM)
No epithelial abnormality is found
Atypical Squamous Cells of Undetermined Significance (ASC-US)
Atypical epithelial cells that have changes not definitive of a low grade squamous intraepithelial lesion.
Criteria
- Nuclei are approximately 2.5 to 3 times the area of the nucleus of a normal intermediate cell.
- Slightly increased ratio of nuclear to cytoplasmic area (N/C ratio).
- Minimal nuclear hyperchromasia and irregularity in chromatin distribution.
- Nuclear abnormalities associated with dense orangeophilic cytoplasm (atypical parakeratosis).
Atypical squamous cells of undetermined significance
Atypical Squamous Cells, which can’t exclude a High-grade Lesion (ASC-H)
ASC-US cells which are suggestive of but not definitive for a higher grade SIL (HSIL).
Criteria
- Small cells with a high N/C ratio representing atypical metaplasia.
- Nuclei are 1.5 to 2.5 times larger than normal metaplastic cells.
- N/C ratio may approximate that of HSIL.
Atypical squamous cells that can't exclude a high-grade lesion
Low-grade Squamous Intraepithelial Lesion (LSIL)
Abnormal epithelial cells with changes encompassing human papillomavirus (HPV) and/or mild dysplasia.
Criteria
- Large cells with mature cytoplasm
- Nuclei 3 times normal intermediate nuclei with a slightly increased N/C ratio—may be bi- or multi-nucleated.
- Coarsely granular chromatin which is uniformly distributed (may also be smudged)
- Distinct cytoplasmic borders
Perinuclear cavitation (“Koilocytosis”) may indicate HPV infection or in the presence of atypical changes may be interpreted as LSIL.
Low-grade squamous intraepithelial lesion
High-grade Squamous Intraepithelial Lesion (HSIL)
Abnormal epithelial cells with changes representing high-grade precursors to invasive squamous cancer. This category encompasses moderate dysplasia, severe dysplasia, and carcinoma in situ.
Criteria
- Smaller and less mature cells
- Nuclear hyperchromasia is accompanied by variations in nuclear size and shape
- Chromatin may be fine or coarsely granular and evenly distributed
- Irregular nuclear membrane and may have prominent indentations
High-grade squamous intraepithelial lesion
Squamous Cell Carcinoma
A malignant invasive tumor showing differentiation towards squamous cells.
Criteria
- Marked variation in cellular size and shape.
- Nuclei vary markedly in size and nuclear membranes may be irregular
- and irregularly distributed.
Tumor diathesis may be present.
Descriptions and criteria are taken from The Bethesda System for Reporting Cervical Cytology. Definitions, Criteria by Diane Solomon and Ritu Naya, 2004.
Photos: Cancer Cytology Unit; May 2014
SLPH Cancer Cytology Information
