[Statistical study of metastatic skin cancer--interrelation of the origin of primary tumor, metastatic skin lesions, prognosis and histopathology].

Seventy-five cases of metastatic skin cancers, collected from 15 institutions in West Japan, were included in this study. The most frequently occurring primary tumors were carcinoma of the lung (31%) and carcinoma of the stomach (20%). Metastatic lesions of lung cancer were common on the neck, face and scalp. The anterior part of the abdomen was the most common metastatic site for stomach cancer. The average interval between the appearance of the skin lesion and the detection of the primary cancer was 20 months. Of 23 patients with lung cancer, and of 15 patients with stomach cancer, cutaneous metastasis preceded documentation of the primary tumor in 10 cases of lung cancer and 4 cases of stomach cancer. Three of these 4 cases were signet ring cell carcinoma. The average survival after the development of cutaneous metastasis was 11 months. In 13 cases of lung cancer, it was 4.7 months. The average interval between the appearance of skin lesions and death in 3 patients with squamous cell carcinoma of the lung was 0.8 months.