The clinicopathologic features of cutaneous metastasis were studied in 724 patients. In each instance both the primary tumor and the metastatic lesion in the skin were documented histologically. The most common clinical presentation was that of multiple nodules that had appeared recently in one area of the body. Other forms included inflammatory and sclerodermoid metastatic growths. Metastatic adenocarcinoma usually arose in the large intestine, breast, or lung; squamous cell carcinoma in the oral cavity, lung, or esophagus; and undifferentiated carcinoma in the lung or breast.
Brownstein MH, Helwig EB. Spread of Tumors to the Skin. Arch Dermatol. 1973;107(1):80-86. doi:10.1001/archderm.1973.01620160052015