Mucoepidermoid carcinoma of lung masquerading as urothelial carcinoma of bladder

Background Mucoepidermoid carcinoma (MEC) of the lung is a rare subtype of non-small cell lung cancer. There is no consensus regarding optimal management for this disease. Case report We present a case of MEC of the lung in a 75 year-old female with a history of superficial urothelial carcinoma of the bladder. The patient was found to have an asymptomatic lung mass. Initial biopsy suggested metastatic recurrence of urothelial carcinoma and therefore, cisplatin and gemcitabine chemotherapy was administered prior to surgical resection. Pathological analysis of the resected specimen confirmed a diagnosis of stage IIIA MEC with focal high-grade features including transitional cell-like areas. Adjuvant radiotherapy was administered due to a positive microscopic resection margin. No chemotherapy was given due to lack of supporting data. The patient developed widespread metastatic disease 3 months following completion of radiotherapy and died 1 month later. Conclusion This case demonstrates the possibility of dual pathology in cases where metastatic disease is suspected. The use of small tissue samples may complicate diagnosis due to the heterogeneity of malignant tumours.