Resolution of clonal origins for endometriotic lesions using laser capture microdissection and the human androgen receptor (HUMARA) assay.
OBJECTIVE: To determine the clonal origins of endometriotic lesions using laser capture microdissection and PCR-based HUMARA assay. DESIGN: Molecular genetic study of human tissue. SETTING: Molecular genetics laboratory in an academic setting. PATIENT(S): Twenty patients with endometriosis. Forty specimens of endometriotic lesions from these patients and one specimen of normal endometrium were analyzed. INTERVENTION(S): Laser capture microdissection was used to harvest epithelial cells from single and multifocal endometrial lesions from paraffin-embedded and frozen tissues, and their clonality was determined with the HUMARA assay. MAIN OUTCOME MEASURE(S): Polymerase chain reaction-based HUMARA assay of clonality. RESULT(S): Thirty-eight specimens were polymorphic and thus informative. Most specimens were monoclonal, as determined by the HUMARA assay. In four specimens of multifocal lesions, polyclonality was detected, but upon more refined microdissections and further analyses, we found that each focus was monoclonal individually. CONCLUSION(S): Previously reported polyclonality is very likely to be attributed to the pooling of multifocal lesions or contamination of normal tissues. These results suggest that endometriotic lesions were monoclonal in origin, and in the case of multifocal lesions, each focus originates monoclonally; hence, different foci have independent origins. The monoclonality of endometriotic lesions suggests that they may carry neoplastic potentials, and the apparent independent origins of multifocal lesions suggest that reconstruction of individual lesion histories may help us to understand the initiation and progression of endometriosis.