Vaginal fibrosis (Figure 1 and Figure 2), deposition of fibrous connective tissue or collagen with a few interspersed cells, has been observed in older rats and is often accompanied by some chronic inflammation. Fibrosis needs to be differentiated from neoplasia (fibroma or fibrosarcoma), which is a space-occupying change; in contrast, fibrosis is generally a contracting lesion.
Vagina - Fibrosis should be diagnosed whenever it occurs in the absence of other lesions. Fibrosis present accompanying chronic or chronic active inflammation should be diagnosed only when the degree of inflammation is not commensurate to that of fibrosis (i.e., the fibrosis is more severe than would be expected given the severity of the inflammation). If fibrosis is not diagnosed separately, it should be described in the pathology narrative. Whenever it is diagnosed, fibrosis should be assigned a severity grade.
Greaves P. 2012. Female genital tract. In: Histopathology of Preclinical Toxicity Studies: Interpretation and Relevance in Drug Safety Evaluations, 4th ed. Elsevier, Amsterdam, 667-724.
National Toxicology Program. 1998. NTP TR-477. Toxicology and Carcinogenesis Studies of 1-Chloro-2-propanol (Technical Grade) (CAS No. 127-00-4) in F344/N Rats and B6C3F1 Mice (Drinking Water Studies). NTP, Research Triangle Park, NC.Abstract: https://ntp.niehs.nih.gov/go/9756