Poroma: A 12-Year Experience in Taipei Veterans General Hospital and A Literatures Review

Background: Poroma is a type of rare, benign skin tumor which originates from the sweat glands and is commonly seen on the distal aspect of the extremities. Grossly, the tumor is similar to other skin tumors, making the correct diagnosis a challenge for clinicians. Since porocarcinoma has been recognized de novo, or 100% transformed from a benign poroma, we have been interested in poromas in our institution for the past 12 years. Aim and Objectives: To understand the etiology, clinicopathological characteristics, and the possibility of malignant changes to this type of skin tumor, we present and discuss the patients in our experience, and review the available literature. Materials and Methods: We performed a retrospective analysis of the patients in the Taipei Veterans General Hospital, Taipei, Taiwan, from January 2004 to May 2015. For this study, 101 patients (106 poromas) were enrolled. Tumors with an uncertain diagnosis, or an incomplete description of tumor size or appearance in the medical records were excluded. Results: The patients had a mean age of 68.4 ± 16.4 years, the majority were in the 8th-9th decade of life, and were predominantly men (M:F = 1.5:1). Although poroma is described more commonly at the distal region of the extremities, in our study, head and neck cases account for the highest incidence per unit area, as we distinguish the total body surface into the head and neck, trunk, and extremities. After a mean follow-up of 4.9 years, no local, recurrent poromas were noted after surgical excision. Poly-chemotherapy of lymphoma (8 patients), and bone marrow transplantation of leukemia (2 patients) are found to associate with the occurrence of poroma. None of our cases had malignant transformations. Conclusion: Poroma, a kind of benign skin tumor, is more commonly found on the lower extremities of mid to old age men. Clinically, poroma has no obvious characteristics, and the exact diagnosis is thus made by histopathological analysis. Some authors suggest that porocarcinoma is transformed from poroma 100%, but there are no cases of this in our analysis.