Recognition of atypical reserve cell hyperplasia in cervical smears and its diagnostic significance

In this study, the histological, cytological, and electron microscopical features of cervical atypical reserve cell hyperplasia are presented. The most important feature of atypical reserve cells in smears is the absence of cytoplasm. Thus, they must be recognized on the absence and not on the presence of a feature, which makes identifying these cells a controversial issue. These stripped nuclei are erroneously believed to be degenerated cylindrical cells, and accordingly are ignored. The atypical reserve cell nuclei are easily damaged in the smear process; however, the MIB-1 staining shows that these disrupted nuclei are derived from proliferating cells. In a follow-up histological study of cases diagnosed as mild dysplasia in a smear, it was found that the presence of MIB-1 positive staining atypical reserve cells was closely related to the development of carcinoma in situ. Recognizing the atypical reserve cells and observing their proliferating activity in a smear might prove to be more important than focusing on the better-known dysplastic cells.