Figure 1. A) Hybridization of the TERC gene (yellow) to previously stained routine Papanicolaou (Pap) smears from a patient who later showed regression to normal cytology. This Pap smear was assessed as Pap IIID (cervical intraepithelial neoplasia [CIN1]). Note that the morphologically suspicious cells do not carry extra copies of the TERC genes (two copies per cell only). Two distinct areas of the slide are presented. B) Hybridization of the TERC gene (yellow) to previously stained routine Pap smears from a patient who showed progression. This sample was assessed as Pap IIID (CIN2). Multiple nuclei that appeared aberrant during the cytological screening throughout the slide reveal extra copies of TERC. Note that both larger nuclei and cells with small nuclei reveal increased copy numbers for this gene (lower right area). C) Hybridization of the TERC gene (yellow) to previously stained routine Pap smears from a patient who eventually experienced disease progression. This patient was initially diagnosed with Pap IIID (CIN1, October 2000), but the patient’s disease was considered to have regressed because subsequent Pap smears were normal (2001). However, in 2002 the follow-up Pap smear was assessed as CIN2, and in 2003 as CIN3. Note multiple 3q-positive cells in the sample. D) Hybridization of the TERC gene (yellow) to previously stained routine Pap smears from another patient who eventually experienced disease progression. The patient’s samples were repeatedly judged as morphologically normal, yet she presented with a CIN3 lesion 28 months after her last normal Pap smear. This case revealed four, occasionally five, copies of 3q on a diploid background. Interestingly, the subsequent CIN3 lesion showed the same main signal distribution pattern, supporting the hypothesis of clonal expansion.