PT - JOURNAL ARTICLE AU - Pascal Assouline AU - Paula Husleag AU - Marie-Bénédicte Léger-Ravet AU - Raphaël Saffroy AU - Aldjia Benissad AU - Antoinette Lemoine AU - Gérard Oliviéro TI - Breast metastasis from primary EGFR-mutated lung carcinoma or primary tumor? AID - 10.1183/13993003.congress-2016.PA2828 DP - 2016 Sep 01 TA - European Respiratory Journal PG - PA2828 VI - 48 IP - suppl 60 4099 - http://erj.ersjournals.com/content/48/suppl_60/PA2828.short 4100 - http://erj.ersjournals.com/content/48/suppl_60/PA2828.full SO - Eur Respir J2016 Sep 01; 48 AB - Introduction: breast metastasis from primary lung carcinoma is very rare. However, face to a woman presented with both lung and breast tumors, it is difficult to distinguish a second primary breast cancer from a breast metastasis from lung adenocarcinoma.Case report: We report 2 cases of patients with breast metastasis from a positive TTF1+ adenocarcinoma and deletion in exon 19 of the EGFR gene. The first patient is a non-smoking Asian female who presented a breast metastasis (a unique metastatic site) 29 months after the introduction of first-line chemotherapy. The second female patient is a Caucasian active smoker who developed a multiple sites tumor progression, presenting a bilateral breast metastatic lesion 10 months after the initiation of treatment with a tyrosine kinase inhibitor.In both cases, a TTF1+ positive immunostaining profile and PCR analysis of the breast lesion identified the same EGFR-activating mutation (deletion of exon 19) as in the primary lung tumor.Conclusion: the occurrence of breast metastasis could be a feature of TTF1 positive and EGFR-mutated lung adenocarcinomas. Therefore, In women presenting with breast and lung tumors, immunohistochemical screening for TTF1 expression and EGFR genotyping of both tumors are useful for an effective management.