Stepwise examination for differential diagnosis of primary lung cancer and breast cancer relapse presenting as a solitary pulmonary nodule in patients after mastectomy

Abstract

The distinction of primary lung from metastatic breast cancer is crucial in patients presenting with a solitary pulmonary nodule after mastectomy, because treatment strategies are completely different. Definitive diagnosis of these nodules, however, is often difficult. We assessed the feasibility of our diagnostic approach for these nodules and estimated the frequency of primary lung cancer occurrence in patients after mastectomy. We evaluated solitary pulmonary nodules appearing in 48 patients after mastectomy. For histological examination, CT-guided needle aspiration biopsy (CT-NAB) or trans-bronchial lung biopsy (TBLB) was performed. Besides conventional morphopathological examination, differential diagnosis was performed by immunohistochemical examination and evaluation using a molecular marker (mammaglobin 1). Biopsy specimens were obtained using minimally invasive methods, namely CT-NAB and TBLB, in 91.7% of patients. From 48 patients, differential diagnosis was obtained by morphopathological methods alone in 32, and by immunohistochemical and molecular marker examination in the remaining 16. Final diagnosis was metastatic breast and primary lung cancer in 40 (83.3%) and 8 patients (16.7%), respectively. Our results show the clinical feasibility of our stepwise approach to the differential diagnosis of primary lung cancer and breast cancer relapse presenting as a solitary nodule in patients after mastectomy.