The role of L1-CAM immunohistochemial staining in the diagnosis of abdominal-pelvic cancer of uncertain primary site in women.

The L1 adhesion molecule (L1-CAM,CD171) is over expressed in ovarian and endometrial carcinomas and other tumors derived from the Mullerian tract. Here we evaluated whether L1-CAM could serve as a novel tumor marker for the diagnosis of metastatic abdominal-pelvic cancers of uncertain origin in women.During a 6-year period we investigated 28 patients with metastatic abdominal or pelvic cancer with uncertain primary-origin. In all these cases a thorough clinical, surgical, pathologic and immunohistochemistry evaluation was performed and correlated to the L1-CAM expression as determined by immunohistochemical staining.In 20 patients where the differential diagnosis was primary ovarian or endometrial cancer and primary or recurrent colon cancer, L1 immunohistochemistry staining allowed or supported the correct diagnosis. In four cases L1 staining allowed the correct diagnosis between breast and ovarian cancer. In two cases vaginal metastases of unknown origin were positive to L1 immunohistochemistry staining implying their mullerian origin and one case each of inguinal lymph node metastases and abdominal wall cancer that were positive for L1-CAM, allowed the correct diagnosis of primary ovarian cancer. In a whole, L1-CAM was of crucial role of delinating the final diagnosis in 17 of the 28 cases described.L1-CAM, a new tumor marker, was found to be specific for metastatic cancer originating from mullerian origin. Its incorporation into the conventional immunohistochemistry analysis in cases of cancer of unknown primary in women, allows a correct diagnosis and subsequent treatment in the majority of cases with abdominal-pelvic carcinomatosis.