Distribution of type IV collagen immunoreactivity to assess questionable early stromal invasion

To determine if the immunocytochemical delineation of subepithelial basement membrane can be used in the assessment of questionable early invasive cervical carcinoma.

The distribution of immunoreactive type IV collagen was examined in 15 cervical biopsy specimens in which the reporting pathologist had specifically described difficulty in assessing or excluding early invasion of subepithelial stroma associated with cervical intraepithelial neoplasia (CIN). The results were compared with those from biopsy specimens showing CIN III (N = 8), carcinoma with definite early stromal infiltration (FIGO stage 1a1) (n = 6), and more advanced invasive squamous tumours (FIGO stages 1a2 to 3) (n = 8). In all cases the immunocytochemical findings were assessed in relation to serial sections stained with haematoxylin and eosin.

Six of the 15 diagnostically problematic biopsy specimens were considered, on review, to show early infiltration of subepithelial tissue and putative invasive foci were consistently absent in basement membrane. A similar pattern was observed in the "definite" early invasive cases. Eight problematic biopsy specimens were considered to show only in situ neoplasia; five of these had intact though occasionally attenuated basement membrane, three showed focal type IV collagen defects. In the remaining case biopsy trauma precluded further assessment. Basement membrane defects were identified in five of eight cases of CIN III, while three of eight squamous carcinomas showed partial retention of type IV collagen immunoreactivity around invasive tumour cell nests.

Defects in subepithelial basement membrane occur in in situ and invasive neoplasia in the uterine cervix. Immunocytochemical staining for type IV collagen is of limited diagnostic value in the assessment of biopsy specimens with questionable early stromal invasion.