Clinicopathological significance of androgen receptor expression in extramammary Paget disease: An analysis of 92 patients.

Extramammary Paget disease (EMPD) is a rare cutaneous malignant neoplasm arising in apocrine gland-rich areas. Although - like normal apocrine glands - EMPD frequently expresses androgen receptor (AR), the clinical significance of AR expression remains unclear. The present study investigated the clinicopathological impact of AR expression in EMPD. Immunohistochemistry for AR was performed in a retrospective cohort of 92 EMPD patients with 108 EMPD lesions, including 102 primary lesions, five lymph node [LN] metastases and one local recurrence. The total AR staining score was calculated as staining intensity score (IS 0-3) × positive-cell percentage score (PS 1-4). Expression levels were graded as Grade 1 (scores 0 and 1), Grade 2 (scores 2-4), and Grade 3 (scores 6-12). Higher expression grade was correlated with tumor thickness (P = 0.011), LN metastasis (P = 0.008), and higher EMPD stage (P = 0.023). Grade 1 EMPDs did not invade into the dermis and did not generate metastatic and/or recurrent lesions, whereas only Grade 2 or 3 EMPDs did so. AR expression in invasive components was significantly higher (P = 0.023) than in non-invasive components remaining within the epidermis. AR expression was further elevated in metastatic and/or recurrent lesions relative to locally invasive lesions (P = 0.014). These results clearly indicate that increased AR expression is associated with malignant progression of EMPD and that androgen blockade might be an effective therapy. Furthermore, AR expression assessed by immunohistochemistry may have potential for prediction of LN metastasis and local recurrence in EMPD.