An unusual case of sarcomatoid renal cell carcinoma presenting in the skin by direct extension at a laparoscopic port site.

Although renal cell carcinoma (RCC) is known for its propensity to metastasize widely throughout the body, cutaneous metastases are uncommon and seen in less than 3% of RCCs. A 56-year-old man presented with a painful red lesion with satellite nodules on his abdomen at a laparoscopic port site from a partial nephrectomy for a pT1a clear-cell RCC that was performed 28 months prior. The lesion was excised; however, after excision the lesion recurred with continued pain and drainage from the surgical site. This was treated with multiple courses of antibiotics. Because of the persistent nature of the lesion, it was re-biopsied, and an atypical, keratin-positive, spindle-cell proliferation was identified within the dermis. The patient's previous skin excision was reexamined, and the same atypical cells were identified within large areas of necrosis, granulation tissue, and fibrosis. Further workup was performed on the initial excision, and the atypical cells showed expression of CD10, CAIX, PAX8, EMA, and vimentin, consistent with cutaneous involvement by RCC. Because of the rarity of skin metastases in RCC and the location at a previous laparoscopic port site, this lesion is presumed to have resulted from direct extension of tumor at the time of surgery.