Cervical FISH testing for triage and support of challenging diagnoses: A case study of 2 patients

Abstract

Patient 1: In June 2014, this patient was diagnosedwithatypicalsquamous cells of uncertain significance(ASCUS) aftera routinescreening cervical Papanicolaou (Pap)test. Reflexhigh riskhuman papillomavirus (HPV) testing was performed; the results werepositive(genotyping was not performed). Subsequentendocervicalcurettageshowed asmall focusof immature, atypical squamous cells with abnormallypositivep16staining and an abnormallyincreased proliferativeindexstaining pattern (evaluated with Ki67)(Images1A-1C). These findings strongly suggesteda high-grade lesion; nevertheless, due totheminuteand focal nature ofthesefindings, a diagnosis was rendered ofsquamous dysplasia, cannotexclude high grade dysplasia. Additional follow-upwasrecommended,andthe option ofa fluorescentinsituhybridization (FISH) assay(HPV-4C, using reagent manufacturedbyCancer Genetics Italia S.r.l.) was also suggested as a method of triageto be performed using thesameThinprep collection media usedto createthe Pap test. The results ofthe FISH assaywere positive,with 6.6%of cells showing gain ofthe 3q26 region(Image1D). With this knowledge, the gynecologistperformeda cervical loopelectrosurgical excision procedure(LEEP), which revealed moderate squamous dysplasia (cervical intraepithelial neoplasiagrade2 [CIN 2]) supported by strongandabnormal p16/Ki-67 co-expression (Images1E-1G). Patient 2: In June 2013, this patient was diagnosed with atypical glandular cells (AGUS) and was shown to have high-risk human papillomavirus (HPV) positivity. (Again, genotyping was not performed.) The subsequent biopsy showed mild reactive atypia of the glandular cells, which did not completely correlate with the atypical cells revealed by the Papanicolaou (Pap) test. Therefore, further follow-up was recommended. A fluorescent in situ hybridization (FISH) assay was performed on the specimen assayed via the AGUS Pap test; the FISH assay yielded positive results, showing many cells with a gain of 3q26 and 5p15 regions above the established cutoff values. A repeat Pap test was performed, which also was interpreted as indicating AGUS. Results of a second HPV-4C FISH assay showed numerous (14.6%) cells with a gain of 3q26 and 5p15 regions (Image 2A). Repeat cervical and endocervical biopsies showed scant atypical glands in otherwisegenerous biopsies (Image 2B). Supported by abnormal p16 and Ki-67 immunohistochemical staining results (Image 2C and 2D) and the knowledge of the abnormal FISH assay results, the pathologist diagnosed the patient with endocervical adenocarcinoma in situ (AIS). The results of a subsequent LEEP confirmed the diagnosis of endocervical adenocarcinoma in situ with negative resection margins. Laboratory Findings: Abnormal Papanicolaou (Pap) test results with high risk of human papilloma virus (HPV) positivity and scant lesional tissue, as revealed by cervical/endocervical biopsies.