Comparative immunohistochemical studies of endometriosis lesions and endometriotic cysts

Objective: To compare immunohistochemical staining patterns in noncystic and cystic endometriosis lesions. Design: Experimental. Setting: Archived pathology material in an academic research environment. Patient(s): Endometriosis tissues from the pathology archives including slide tissue sections and blocks. Intervention(s): None; this was a retrospective study. Main Outcome Measure(s): Immunohistochemical staining of the tissues was performed using anti-bcl-2, anti-p53, anti-matrix metalloproteinase IX, and anti-collagen VI antibodies. Staining was qualitatively assessed in terms of extent and intensity. Result(s): p53 showed no staining in both groups. Anti-bcl-2 stained 100% (30/30) of endometriosis lesions compared with only 23% (7/30) of endometriotic cysts (P<.0001), and anti-matrix metalloproteinase IX stained 85% (23/27) of endometriosis lesions and only 39% (14/36) of endometriotic cysts (P=.0003). Anti-collagen VI, however, stained only 6% (2/35) of endometriosis lesions and 75% (21/28) of endometriotic cysts (P<.0001). Conclusion(s): Compared with endometriosis lesions, endometriotic cysts display different expression of proteins with relative overexpression of collagen VI and underexpression of bcl-2 and metalloproteinase IX. This report is the first comparative immunohistochemical study showing these differences.