Purpose: To determine the frequency of single lung metastasis, primary lung cancer, and benign lesions in patients with a solitary lung nodule and a primary extrapulmonary neoplasm.
Materials and methods: The authors evaluated the electronic charts of 149 patients with an extrapulmonary malignant neoplasm and a solitary pulmonary nodule. The histologic characteristics of the nodule were correlated with those of the extrapulmonary neoplasm and with patient age and smoking history.
Results: Patients with carcinomas of the head and neck, bladder, breast, cervix, bile ducts, esophagus, ovary, prostate, or stomach were more likely to have primary bronchogenic carcinoma than lung metastasis (ratio, 25:3 for patients with head and neck cancers; 26:8 for patients with other types of cancer combined). Patients with carcinomas of the salivary glands, adrenal gland, colon, parotid gland, kidney, thyroid gland, thymus, or uterus had fairly even odds (ratio, 13:16). Patients with melanoma, sarcoma, or testicular carcinoma were more likely to have a solitary metastasis than a bronchogenic carcinoma (ratio, 23:9). Thirty patients had a benign nodule. There was substantial overlap in age distribution among the patients with benign disease, lung cancer, and metastasis, although no patient younger than 44 years had a lung cancer. Smokers had a 3.5-fold higher chance of developing lung cancer compared with nonsmokers.
Conclusion: The likelihood of a primary lung cancer versus a metastasis depends on the histologic characteristics of the extrapulmonary neoplasm and the patient's smoking history.