Sex-dependent expression of prostatic markers and hormone receptors in cystic tumor of the atrioventricular node: A histopathological study of three cases.

We pathologically investigated three autopsy cases of cystic tumor of the atrioventricular node (CTAVN) with sudden death. Case 1 was a 36-year-old woman without any clinical history. Case 2 was a 76-year-old man with an implanted pacemaker for complete atrioventricular block. Case 3 was a 45-year-old man with a history of first-degree AV block and sinus bradycardia. Microscopically, all three cases showed the bilayered structure of tumor glands and corpora amylacea in the glandular lumens. Immunohistochemically, the inner cells of the tumor glands were positive for cytokeratin CAM5.2, CEA, EMA, olfactomedin-4 and alpha-methylacyl-coenzyme A racemase; the outer cells were positive for p63 and cytokeratin high molecular weight. In Case 1, androgen receptor and estrogen receptor were negative; progesterone receptor was focally positive in both the inner and outer cells. In Case 2, androgen receptor showed intermediate positivity in the inner cells; estrogen receptor and progesterone receptor were positive in the outer cells. Positive expression of both prostate-specific antigen and prostate-specific acid phosphate were found in the inner cells of both male cases. Because CTAVN cells exhibit different degrees of the prostatic phenotype depending on the patient's sex, we believe that CTAVN may originate from urogenital sinus tissue in some cases.