MON-331 Pulmonary Carcinoidosis Presenting with Persistent Pneumothorax

Introduction: Lung neuroendocrine (NET) or carcinoid tumors are a rare group of pulmonary neoplasms characterized by insidious clinical behavior. In this report, we present a case of pneumothorax refractory to conservative management with concomitant pulmonary carcinoidosis. We also discuss the diagnostic and management approach followed in such cases. Case: 80 year-old male with history of asthma and Type 2 DM presented to the ER with worsening cough and shortness of breath, and was found to have a left sided spontaneous pneumothorax. Chest tube was inserted. However, due to persistent leak, PleurX catheter was placed, and patient was discharged home afterwards. However, he presented with subcutaneous emphysema on the same day and was subsequently readmitted. Persistent pneumothorax was managed conservatively. PleurX catheter was attached to underwater seal with negative pressure and respiratory status was optimized given evidence of asthma exacerbation. Treatment with Methylprednisolone IV, Montelukast, Tiotropium, Mometasone Furoate/Formoterol inhalers was initiated. However, air leak persisted despite conservative management for 13 days. CT surgery elected to proceed with VATS. Multiple wedge resections were performed along with partial pleurectomy, lysis of adhesions and decortication of left upper lobe. Pathology revealed a sub-pleural 5-mm carcinoid tumor with solid nests of cells along with lung tissue with emphysematous changes, pleural scarring and bullous formation. No nuclear pleomorphism or mitotic figures were noted. Immunoperoxidase stains were positive for TTF-1, synaptophysin, chromogranin and CD56 and negative for CK5/6, calretinin and P-40. Serum Chromogranin A (CgA) was elevated 431 ng/l. Post-op course was uncomplicated and patient was discharged to a rehab facility. Discussion: Lung NETs account for 1-2% of all lung malignancies in adults and 30% of all NETs. Incidence ranges from 0.2-2/100,000 population per year. While some patients may be asymptomatic, others present with obstructive symptoms due to mass effect. Incidence of pneumothorax as a complication of lung neoplasms is rare (0.05-1.4% of all pneumothoraces). Clinical presentation includes carcinoid syndrome, Cushing's syndrome and acromegaly. Diagnosis is confirmed either by bronchoscopic biopsy (for central lesions) or by transthoracic needle biopsy (for peripheral lesions). For patients with localized lung NETs, surgical resection is the treatment of choice. Lung NETs have an excellent prognosis following surgical resection, with 5-year survival rates of 87-100%. Immunohistochemical identification utilizes tissue markers like synaptophysin, neuron-specific enolase, and chromogranin. Serum CgA is usually elevated and is used as a marker to assess disease progression, response to therapy, or recurrence after surgical resection.