Unusual subcutaneous splenosis occurring in a gunshot wound scar: pathology and immunohistochemical identification

Splenosis usually occurs after traumatic rupture of the spleen with autotransplantation of splenic tissue to ectopic sites. Most commonly, it occurs as intraperitoneal nodules, which are found either incidentally or after symptomatic complications. Subcutaneous splenosis is a rare condition mostly observed in abdominal surgical scars. Reported herein is a case of subcutaneous splenosis developed in an exit gunshot wound scar on the left lower chest wall 9 years after splenectomy. The lesion presented as an asymptomatic subcutaneous nodule, which was excised under the impression of a skin tumor. Microscopically, there were multiple subcutaneous nodules resembling splenic tissue with red and white pulp. They were confirmed to be ectopic splenic tissue by immunohistochemical staining of the vascular lining cells (CD8+, CD31+, and CD34-). Only 11 cases of subcutaneous splenosis have been reported before. The present case was the third case occurring in an exit gunshot wound scar, and the diagnosis was confirmed by immunohistochemical study.