The cervical epithelium is replaced by bland cells with vertically oriented nuclei. The superficial layer consists of horizontally oriented cells with abundant pink cytoplasm, resembling umbrella cells seen in urothelium. Note the absence of cytologic atypia and mitotic activity.
The nuclei are ovoid with a fine chromatin pattern and inconspicuous nucleoli. Longitudinal grooves may be seen in a few cells (lower center image).
Transitional metaplasia of the cervix is often associated with atrophy. This change usually occurs on the ectocervix and may sometimes extend down into endocervical glands. The epithelium is replaced by multiple layers of cells with vertically aligned ovoid nuclei and an overlying superficial layer of horizontally oriented 'umbrella' cells. Thus, the overall picture is virtually identical to that of urothelium found in the bladder.
At first glance, the overall impression may be that of a high-grade squamous intraepithelial lesion, as the cells may be disoriented and tightly packed. However, a closer inspection will reveal that unlike HGSIL, there is neither cytologic atypia nor high mitotic activity.1
An interesting study conducted by Ng (2001) on seven cases of transitional metaplasia of the cervix revealed the presence of HPV in all seven cases, with HPV type 58 as the most common subtype. The clinical implications of this is not yet clear, as transitional metaplasia has always been considered a benign reactive process commonly associated with mucosal atrophy. Further studies will need to be conducted to confirm and examine the significance of HPV infection in transitional metaplasia of the cervix.2
→The disorientation of cells seen in transitional cell metaplasia may mimc HGSIL, but the cytology is bland.
1 Kurman RJ, Norris HJ, Wilkinson E. Tumors of the Cervix, Vagina and Vulva: Atlas of Tumor Pathology. Third Series Fascicle 4. Washington DC; AFIP: 1990: Section 5.1.4.
2 Ng WK, Cheung LK, Li AS et al. Transitional cell metaplasia of the uterine cervix is related to human papillomavirus: molecular analysis in seven patients with cytohistologic correlation. Cancer. 2002 Aug 25;96(4):250-8.