Cutaneous metastasis from lung adenocarcinoma presenting before discovery of the primary malignancy: a case report.

Cutaneous metastasis from lung adenocarcinoma is rarer than liver, adrenal, brain, bone and other distant metastases, and the prognosis is very poor. We report a case of a 42-year-old Asian male lung adenocarcinoma patient with lymph node metastases and cutaneous metastases to the right chest wall that appeared during the comprehensive treatments, without any lesion previously found in the lung. The patient was positive for the EGFR18 exon and had an excellent tumor response to the EGFR tyrosine kinase inhibitor (EGFR-TKI) with a duration of efficacy of up to 22 months. Then, the area of right chest wall lesions expanded with ulceration, and gene detection from peripheral blood indicated that the patient acquired resistance to the administered EGFR-TKI therapy. A bilateral pleural effusion occurred 1 month later upon changing treatment to the third generation of EGFR-TKI. Then, the pleural effusion was controlled, but a change in the chest wall skin lesions was not obvious until after treatment with bevacizumab combined with cisplatin pleural perfusion. Currently, the patient is administered S-1 for maintaining treatment. Current follow-up time is more than 48 months, and the KPS score is 80 points. Through this case and a review of relevant literature, we discuss the clinical manifestations, diagnosis, treatment and prognosis of this disease and intend to provide a reference for the clinical diagnosis and treatment of similar diseases.