Mediastinal Cyst Mimicking Malignancy in a Pipe Smoker

Abstract

INTRODUCTION: Mediastinal masses in both adults and children are concerning for malignancy, especially thymomas and lymphomas. Benign tumors may be present as well. When cystic lesions are found in the mediastinum, they tend to be bronchogenic, thymic, or pericardial. Solitary cystic mediastinal lymphangioma is rare and almost exclusively found in the pediatric population, most commonly in the head and neck region. CASE PRESENTATION: A 62 year-old male pipe smoker with a history of prostate cancer presented to the emergency department with new onset atrial fibrillation. A right paratracheal mass was incidentally found on CT chest and he was referred to pulmonary clinic for further evaluation. EBUS-TBNA was performed showing a 24mm cystic appearing lesion in the 4R region and TBNA drained 29 mL of cystic fluid. Cytology was negative for malignant cells and repeat chest CT showed significant decrease in size of the mass with a presumptive diagnosis of benign bronchogenic cyst. Follow-up CT two months later showed recurrence of the cyst, although he remained asymptomatic. He opted for resection and was taken for VATS. Pathology returned with the diagnosis of lymphangioma. DISCUSSION: Cystic mediastinal lymphangioma (CML) is an extremely rare vascular tumor originating from lymphatic vessels. Less than 1% occur in the mediastinum and greater than 90% discovered before the age of 2. Usually an incidental finding, CML is benign but may compress local structures or become infected. It's appearance on CT often resembles adenopathy or a mass. In our adult pipe smoking patient with a personal history of cancer, malignancy needed to be excluded. EBUS-TBNA has been reported as a treatment for CML however recurrence occurred after 2 months in our patient. Diagnosis was not made until surgical resection as it was initially thought to be a bronchogenic cyst. Although recurrence has been reported following surgery, sclerotherapy is emerging as a promising treatment option. CONCLUSIONS: Lymphangioma is a benign yet rare cause of mediastinal cyst and often mimics malignancy. Surgical resection and sclerotherapy may be curative.