Skin metastases from lung cancer.

Cutaneous metastases from the lung are rare but must be ruled out in patients with suspicious skin lesions and history of smoking or lung cancer. All histological types of lung cancer may metastasize to the skin and clinical lesions are variable. The percentage of patients with lung cancer that develop cutaneous metastases ranges from 1 to 12 percent. In 20-60 percent of cases the skin lesions present before or synchronously with the diagnosis of the primary tumor. Skin lesions are often described as nodular, mobile or fixed, hard or flexible, single or multiple, and painless. Histologically, cutaneous metastases from the lung are frequently moderately or poorly differentiated. IHC markers that may be useful in these cases are anti-thyroid transcription factor (TTF) and CK7/20. Treatment of solitary cutaneous metastases usually includes surgery alone or combined with chemotherapy, and/or radiation. If multiple cutaneous lesions or internal metastases exist, chemotherapy is the primary option. Cutaneous metastases and their primaries in the lung are usually incurable and suggest an unfortunate prognosis. Poor prognostic indicators include non-resectable or small-cell primary tumors, multiple cutaneous metastases, or other distant metastases. Mean survival is usually about 5-6 months.