Squamous carcinoma of the cervix, cervical intraepithelial neoplasia (CIN) and atypical squamous cells of undetermined significance (ASCUS)
 
A dense three dimensional cluster of undifferentiated tumour cells in a smear from an invasive carcinoma. The hyperchromatic nuclei overlap and mould each other. The abnormal nucleus structure becomes apparent at higher magnification and the squamous nature of the lesion can be ascertained by examining the edge of the cluster where the cytoplasmic structure can be seen.