INTRODUCTION:Idiopathic pleuroparenchymal fibroelastosis is a newly described interstitial lung disease. Clinical presentation is similar to other described chronic idiopathic interstitial lung diseases. Characteristic radiographic findings include pleural thickening, fibrosis, upper lobe predominance, volume loss, architectural destruction, traction bronchiectasis, and honeycombing. Pathologic findings include visceral pleura fibrosis, homogenous subpleural fibroelastosis, sparing of the distal parenchyma, patchy lymphoplasmacytic infiltrates, and fibroblastic foci at the leading edge of fibrosis. The rarity of this disease affords limited experience as related to patient management. This case describes a unique complication developing after single right lung transplantation in a 68 year-old male with idiopathic pleuroparenchymal fibroelastosis.
CASE PRESENTATION:A 68 year-old male presented with dyspnea on exertion and chronic non-productive cough in 2001. Past medical history was significant for allergies and medications included omalizamab and azelastine. He was a life long non-smoker with no significant exposure history. Initial evaluation revealed normal pulmonary function test (PFT’s) and cardiopulmonary exercise testing. Thorax CT scan showed patchy nonspecific infiltrates. He was followed expectantly. In 2004 he noted worsening cough and dyspnea. PFT’s revealed decreased total lung capacity (TLC), forced vital capacity (FVC), and diffusing capacity for carbon monoxide (DLCO) (60%, 63%, and 65% predicted). High resolution CT thorax showed predominantly upper lobe, pleural based abnormalities, bronchiectasis, and extensive interstitial opacities. Therapy with colchicine, N-acetyl cysteine, and azathioprine was initiated. Open lung biopsy was obtained. Pathological findings were consistent with a diagnosis of idiopathic pleuroparenchymal fibroelastosis. Despite medical therapy, the patient experienced clinical worsening and progressive decline in PFT’s (TLC 48%, FVC 29%, and DLCO 38% predicted). He did not however require supplemental oxygen. Referral for lung transplantation was made and the patient underwent single right lung transplantation in December 2005. Post-transplant course was uncomplicated without any significant rejection episodes. However, in January 2007 the patient noted worsening dyspnea on exertion. Sedentary room air saturation was normal, however exertion resulted in desaturation to 82%. Spirometry values remained stable, transbronchial biopsy did not suggest rejection, and chest CT angiogram was negative for pulmonary emboli or infiltrates. Ventilation/perfusion scan was normal in the transplanted lung with differential functioning showing 89% of perfusion to the transplanted lung. Matched ventilation/perfusion defects were noted in the native lung. Exercise echocardiography with contrast was notable for preserved cardiac function and evidence of an intrapulmonary shunt. Pulmonary angiogram showed normal pulmonary artery pressures, no evidence of thrombus, and no evidence of arteriovenous malformation. Selective pulmonary angiograms during exercise noted increased perfusion to the native lung during exercise associated with arterial desaturation. These findings supported exercise induced perfusion to the native lung as the cause of the patients dyspnea and hypoxia. Treatment options explored included left pneumonectomy and left lung transplantation. In March 2007, the patient underwent a singe left lung transplant. The post-transplant course has remained unremarkable and the patient is active without oxygen requirement.
DISCUSSIONS:Single lung transplantation for idiopathic interstitial lung diseases is well described. Recently quantitative lung perfusion was evaluated in patients with emphysema and idiopathic pulmonary fibrosis, after single lung transplantation. Exercise was notable for small but significant increased perfusion to the native lung. A similar physiological response to exercise was noted in this patient with idiopathic pleuroparenchymal fibroelastosis. However, the resulting shunt was substantial and resulted in exercise induced hypoxemia.
CONCLUSION:This is the first reported outcome for single lung transplantation in a patient with idiopathic pleuroparenchymal fibroelastosis. Given the severity of intrapulmonary shunting developing post transplant, consideration for bilateral lung transplantation in this patient population may be warranted.
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