squamous cell carcinoma of lung with unusual site of metastasis

background: lung cancer ranks among the most common and most lethal malignancies worldwide. once vascular or lymphatic invasions occur, metastatic dissemination to distant sites is common. bone, liver, adrenals, and brain are the most frequent sites of the distant disease. in this study we present a case of squamous cell carcinoma of lung with metastasis of the left knee bursa.case presentation: a smoker man presented with cough and hemoptysis and squamous cell carcinoma of lung was diagnosed. fourteen months later he developed pain and swelling of left knee. the biopsy and pathologic examination of the left knee bursa showed involvement of the bursa.conclusion: squamous cell carcinoma of lung can metastasize in the unusual sites of the body.