DIAGNOSING PULMONARY ALVEOLAR PROTEINOSIS WITH CRYOBIOPSY: A CASE REPORT

SESSION TITLE: Pulmonary SESSION TYPE: Global Case Reports PRESENTED ON: 10/10/2018 01:00 PM - 02:00 PM INTRODUCTION: Pulmonary alveolar proteinosis (PAP) is a rare disease due to surfactant buildup in alveolar spaces. The diagnosis requires pathological proof of tissue, either through bronchoscopy or video-assisted thoracoscopic surgery (VATS) (1). Cryobiopsy is a new technique for obtaining tissue samples and has gained interest in the use of diagnosing lung parenchymal diseases . However to our knowledge, diagnosing PAP with cryobiopsy is rarely reported. CASE PRESENTATION: A 54-year-old male presented with intermittent coughing and dyspnea upon exertion for 6 months. Chest X-ray revealed bilateral increased infiltration. Lab results including autoimmune workup were unremarkable. Sputum culture revealed growth of nontuberculous mycobacteria in 1 set of 3 sets of cultures. Chest computed tomography(CT) showed extensive patchy ground-glass opacities superimposed with thickened interlobular septa compatible with a “crazy paving” pattern. Conventional forceps biopsy through bronchoscopy and cryobiopsy were both performed. Bronchoalveolar lavage and brush cytology were nondiagnostic. Pathological results of the forceps biopsy revealed only chronic inflammation, and that of cryobiopsy revealed granular proteinaceous exudate filling alveolar space, consistent with pulmonary alveolar proteinosis. DISCUSSION: The diagnosis of PAP generally requires radiological imaging and histopathology specimens (1). Transbronchial forceps biopsy was conventionally used to obtain tissue samples and yielded a diagnostic rate of 73%. Combination of BAL, brush cytology, and forceps biopsy improved diagnostic sensitivity to 85.3% but increased procedure time and cost (2). Sensitivity and specificity of VATS was around 90%, but VATS was rarely needed for diagnosis (2).Recently, cryobiopsy has been used for diagnosing parenchymal lung disease and carries several advantages. It can keep the tissue architecture intact while acquiring an adequately sized specimen, but without increasing the risk of associated complication (3). Iftikhar et al. noted that crobiopsy had a diagnostic yield of 83.7% (3). In our case, we did both forceps biopsy and cryobiopsy. Diagnosis of PAP was made from specimens from cryobiopsy but not forceps biopsy. Specimen size from cryobiopsy was 0.5x0.5x0.2 cm, almost twice the volume of the 0.2x0.2x0.1cm size from forceps biopsy. A larger tissue sample may allow better analysis of the lesion. CONCLUSIONS: Diagnosis of PAP by cryobiopsy has been rarely reported in previous literature. Despite the small number of published cases, cryobiopsy appears to be an excellent tool with rising potential for diagnosing PAP and other diffuse lung parenchymal disease. Further large studies are needed to establish the indication for cryobiopsy. Reference #1: Trapnell BC, Whitsett JA, Nakata K. Pulmonary alveolar proteinosis. N Engl J Med 2003;349:2527-39. Reference #2: Govert, Joseph A., et al. "Cost-effectiveness of collecting routine cytologic specimens during fiberoptic bronchoscopy for endoscopically visible lung tumor.” Chest 109.2 (1996): 451-456. Reference #3: Iftikhar, Imran H., et al. "Transbronchial Lung Cryobiopsy and Video-assisted Thoracoscopic Lung Biopsy in the Diagnosis of Diffuse Parenchymal Lung Disease. A Meta-analysis of Diagnostic Test Accuracy.” Annals of the American Thoracic Society 14.7 (2017): 1197-1211 DISCLOSURES: No relevant relationships by Teressa Ju, source=Web Response No relevant relationships by Chi Chan Lee, source=Web Response No relevant relationships by meng fang shen, source=Web Response No relevant relationships by CHIH-YEN TU, source=Web Response