Atypical immature metaplasia (AIM). A subset of human papilloma virus infection of the cervix.

170 cases of cervical condylomata and 60 cases of high-grade cervical intraepithelial neoplasia (CIN II/LLL) were reviewed for evidence of atypical immature squamous metaplasia (AIM). AIM was detected in association with 34% of condylomata cases and 16% of high-grade CIN cases. 37 cases of AIM alone were reviewed and almost all presented with a cytologic diagnosis of CIN I or condyloma and a colposcopic appearance of white epithelium with or without punctation and mosaic structure. The mean age of patients was 27 years for AIM 27 years for condylomata 32 years for CIN II and 37 years for CIN III. 75% of condylomata 16% of AIM and 0% of CIN lesions were positive by immunoperoxidase techniques. Although AIM shares similar epidemiologic morphologic and biologic characteristics with condylomata it is a distinct histologic entity. When AIM is found alone in biopsy material careful correlation of cytology colposcopy and biopsy results should be performed and therapy should be based on the size and distribution of the lesion. Finally it is suggested that the high prevalence of so-called dysplasia in populations exposed to diethylstilbestrol (DES) may reflect human papilloma virus infection rather than intraepithelial neoplasia.