[Controversial categories in cytopathology of the uterine cervix. I. ASCUS: atypical squamous cells of undetermined significance].

ASCUS (Atypical Squamous Cells of Undetermined Significance) is a class for reporting cervical cytopathologic diagnoses. The Bethesda System (TBS) introduced ASCUS in 1988 and then defined this cytologic class further. Since the initial subclassification in probably reactive or probably neoplastic , TBS proposed different subgroups for a correct clinical management. At present, the subgroups are the following: ASCUS a) due to compromised specimen (poor processing or obscuring material); b) with mature intermediate-type cytoplasm; c) in postmenopausal women; d) atypical metaplasia; and e) with orangeophilic cytoplasm. Generally, clinical management of ASCUS presents 3 options: 1) cytologic follow-up (colposcopy only in a persistent diagnosis of ASCUS); 2) colposcopy; and 3) both Human papillomavirus testing and Pap-test. These options may be adopted in the ASCUS type b) and e) whereas in the type c) only in postmenopausal women receiving hormone replacement therapy. In the ASCUS type a), Pap-test should be immediately repeated (processing defects) or after therapy (excessive inflammation). In postmenopausal women not receiving hormone replacement therapy, the Pap-test has to be repeated after topical estrogen therapy. In ASCUS type d), a more aggressive follow-up is needed, such as colposcopy and eventual biopsy. Therefore, in the ASCUS diagnosis an effective communication between cytopathologist and clinician is needed for a correct clinical management.