[Clonality of the peripheral papilloma and cancerous cells of breast].

Objective: To study the clonality status of peripheral papilloma (peri-MP), ductal carcinoma in situ (DCIS), and normal tissue of the breast using an assay based on inactivation mosaicism of the length-polymorphic X-chromosomes at the androgen receptor (AR) locus and to explore a reliable way to distinguish the benign and malignant (or pre-malignant) cases judged morphologically.

Methods: Specimens of breast tissues were obtained from 26 cases of peri-PM, 25 cases of peri-PM with atypical ductal hyperplasia (ADH), and 27 cases pf DCIS, 16 cases of developed canceration, and 20 normal women. DNA was extracted and amplified via nested-PCR with or without previous digestion by the methylation-sensitive restriction endonuclease Hha I. The products were resolved on denaturing polyacrylamide gels and visualized through silver staining. The clonality of these samples was analyzed by showing the lanes.

Results: Loss of polymorphism at the AR locus was found in all the cases with DCIS and in 10 cases (10/25, 40.0%) of peri-PM with ADH, indicating the monoclonality of the tumor. Twenty-four cases (92.3%) of the 26 cases with peri-PM and the 20 specimens of normal tissue were shown to be polyclonal. In the 16 cases of developed canceration identical X chromosome inactivation (monoclonal alterations) was observed in the cancer focus, parts of peri-PM with ADH, and the part of DCIS.

Conclusion: Normal breast tissue and peri-PM show polyclonality and the peri-PM with ADH shows monoclonality. Clonality analysis may be a useful modality to screen high-risk cases from precancerous lesions or to distinguish between the benign hyperplasia and early carcinoma.