Middle Lobe Syndrome Due to Calcified Adenopathy

Can Respir J Vol 21 No 4 July/August 2014 A 43-year-old nonsmoking man presented with a two-year history of recurrent respiratory infections. He had previously been given a clinical diagnosis of asthma. A review of systems was negative for aspiration, constitutional symptoms, occupational exposures and risk factors for tuberculosis and HIV. Spirometry demonstrated reduced forced expiratory volume in 1 s (78% predicted) without airflow limitation, and a methacholine challenge test was negative for asthma. Immunoglobulin levels and complete blood counts were normal. A chest radiograph (Figure 1) was abnormal, prompting a computed tomography (CT) scan of the thorax (Figures 2A and 2B). Bronchoscopic visualization of the right middle lobe bronchus revealed complete obstruction by inflamed bronchial mucosa and external compression. The hilar mass was identified and biopsied under endobronchial ultrasound guidance. A pathological review of biopsy specimens was negative for malignancy and revealed a mixed population of benign lymphocytes with no granulomas (Figures 3A and 3B). No mycobacteria were cultured. The patient was diagnosed with middle lobe syndrome (MLS) secondary to airway compression from an enlarged, partly calcified hilar lymph node, likely secondary to previous Histoplasma exposure given his residence in an endemic area. He was referred to thoracic surgery and scheduled for right middle lobectomy.