Abstract

Background:

Sarcomatoid renal cell carcinoma (SRCC) is a rare and aggressive form of kidney tumor with a worse prognosis than conventional renal cell carcinoma. Skin metastasis is rare. Early recognition and prompt treatment are crucial.

Case Presentation:

A 66-year-old male with a PMH of SRCC presented with a large friable hemorrhagic nodule on the right chin six months after SRCC diagnosis. The skin biopsy confirmed metastatic SRCC. A superficial biopsy revealed an initial diagnosis of pyogenic granuloma. Further examination was recommended for a deeper section due to the lesion’s double-size expansion over 10 days. The second biopsy revealed atypical, keratin-positive, spindle-cell proliferation within the dermis. CD10 and PAX8 showed positive expression in the atypical spindle cell proliferation, consistent with cutaneous SRCC. A similar lesion was identified on the back. Brain metastasis was noted. The patient passed away six months after being diagnosed with SRCC.

Discussion:

Sarcomatoid renal cell carcinoma (SRCC) is a rare and aggressive subtype of RCC accounting for less than 5% of all cases of kidney tumors. Its unique histologic appearance sets it apart from conventional RCC. When this tumor metastasizes to the skin, it usually presents with nodules or masses which can be mistaken for other benign or malignant skin lesions.

Conclusion:

It is important to maintain a high index of suspicion of skin involvement by SRCC. This case highlights the importance of continuous monitoring of patients with SRCC for any signs of metastatic spread, particularly to atypical locations such as the skin, for timely intervention.