Metastatic pulmonary melanoma of 15 months' duration.

The lung is a common site for metastatic foci from extrapulmonary malignancies. Abrams’ found the lung involved, metastatically, in 46.5 per cent of 1,000 autopsied cases of carcinoma. On the basis of radiographic evaluation, Pendergrass’ estimated the incidence of pulmonary metastases from all carcinomas to be 30 per cent and as high as 75 per cent from renal cancer. In general, the secondary deposits in the lung appear on the roentgen film as bilateral, multiple, rounded shadows of varying size and are the result of hematogenous embolic spread. The primary tumors usually associated with this type of lesion arise from the thyroid, genitourinary tract, intestinal tract and bones.