CUTANEOUS METASTASES AS THE FIRST PRESENTATION OF POORLY DIFFERENTIATED RENAL CELL CARCINOMA: A CASE REPORT

Renal cell carcinoma (RCC) exhibits a propensity for unusual and widespread metastasis. Cutaneous metastasis from RCC is a rare and poorly recognized clinical entity. We present a case of scalp and abdominal cutaneous metastases initially mimicking benign cutaneous lesions as the first clinical presentation of poorly differentiated RCC in a 74-year-old male patient.
The patient presented with a painless ulceroproliferative scalp mass evolving for six months, associated with a painless left flank abdominal mass evolving for three months. Apart from these lesions, no other significant clinical findings were noted. Because of their isolated cutaneous presentation and the patient’s preserved general condition, the lesions were initially suspected to be benign. An excisional biopsy of the scalp lesion and a biopsy of the abdominal lesion were therefore performed before radiological assessment and before the diagnosis of the renal tumor. Histopathological examination unexpectedly revealed a poorly differentiated carcinomatous process with clear cell features. Subsequent computed tomography showed a large heterogeneous necrotic right renal mass measuring approximately 10.0 × 7.0 × 18.0 cm, associated with pulmonary, lymph nodal, osseous, subcutaneous, and probable peritoneal metastatic disease. Immunohistochemistry showed diffuse CK AE1/AE3 expression and moderate diffuse CD10 expression in about 50% of tumor cells, favoring renal origin when correlated with radiological findings. No treatment had been initiated at the time of writing, and the patient was referred to a multidisciplinary tumor board for therapeutic decision.
Cutaneous metastasis may be the first sign of disseminated RCC and may initially mimic benign skin lesions. Any atypical, progressive, ulcerated, or multiple cutaneous lesions should raise suspicion of metastatic disease.