ECCRINE POROCARCINOMA: A SERIES OF 11 CASES AND A LITERATURE REVIEW OF RARE CUTANEOUS NEOPLASIA

Introduction: Eccrine porocarcinoma (EP) is rare, accounting for up to 0.01% of all cutaneous tumors. However, it is the most frequent malignant tumor in the eccrine gland, originating from the terminal cells of the intraepithelial portion of the eccrine duct, acrosyringium. In 18 to 50% of cases, it arises from preexisting poroma (benign tumor of the sweat gland derived from the acrosyringe). Malignancies may be induced by immunosuppression or ionizing radiation. It occurs more frequently in the lower limbs (LLM), trunk or head and neck (CCP), 44%, 24% and 24% respectively. It affects adults between 50 and 80 years of age, with a peak incidence in the seventh decade of life. They can be confused with squamous, clear, Paget cells or melanocytes. The diagnosis should be confirmed using immunohistochemistry (IHC), including: carcinoembryonic antigen (CEA), cytokeratin (CK), epithelial membrane antigen (EMA), p53 and p63. CD117 has been reported as highly effective, especially in distinguishing with squamous cell carcinoma. It is related to a high risk of recurrence and up to 20% of cases progress to metastatic disease. Objective The objective of this study is to describe the cases of EP, this rare cutaneous neoplasia, attended at a Federal University Hospital in the last 20 years. Method The cases were selected from an institutional database, based on the pathological characteristics compatible with the neoplasia studied, during a period of 1999 to 2019, with a total of 11 cases. After the selection, a medical review of the data was performed. Results The mean age at diagnosis was 73.5 years (48-93), with a similar prevalence between the sexes. 50% located in upper limbs, 27% lower limbs and the other locations varied between trunk and CCP. The IHC profile was: positives mainly 75% CEA, 100% EMA, 100% P63, 100% Ki67 (50-80%), 100% 34BE12, 100% AE1AE3. All patients were treated with surgery and 36.3% needed margin expansion. No adjuvant treatment was performed and we did not observe relapses or metastases. Three patients died (all due to infectious cause without correlation with the disease), 4 were alive and had no evidence of disease and 4 lost follow-up. Conclusion Eccrine porocarcinoma is a rare malignant cutaneous tumor with high potential for morbidity and mortality. Given its rarity, there are currently no guidelines for diagnosis, treatment and follow-up. Literature is scarce and the vast majority are case reports.