Medical Mystery of the Week

       You are asked to examine a 75-year-old man whose chief complaint is shortness of breath. Four months earlier a CT scan of his chest revealed "Numerous multifocal primary consolidative airspace opacities". He failed to respond to broad-spectrum antibiotics and  is referred to you for diagnosis and treatment.
      On examination he is hyperpneic with a respiratory rate of 14 breaths/minute and a regular pulse of 90 beats/minute. Jugular vein examination reveals a negative Kussmaul sign and cannon A waves. His heart is enlarged 1cm to the left and 2 cm to the right on percussion. His pulmonic closure sound (S2P) is increased at the base and at the apex. Lung examination reveals vesicular breath sounds, bilateral diffuse fine inspiratory crackles, egophony, and vocal pectoriloquy. His chest x-ray is shown below.
      DIAGNOSIS: Cryptogenic organizing pneumonia (COP). Formerly known as bronchiolitis obliterans, COP has no identifiable cause and is classified as a form of idiopathic interstitial fibrosis. This disorder is estimated to account for 5-10% of interstitial lung diseases.

On left: patient's chest x-ray showing patchy areas of consolidation and a diffuse increase in interstitial markings (vis-a-vie interstitial fibrosis). These findings were evident during auscultation - diffuse inspiratory crackles (intersitial fibrosis) and egophony and vocal pectoriloquoy (consolidation). This patient had COP-related pulmonary hypertension as indicated by his loud pulmonic closure sound (S2P). On right: chest x-ray and CT scans of other patients with COP.

On left: Pathophysiology of COP versus progressive (usual) interstitial fibrosis (UIP). On right: causes of secondary organizing pneumonia. 

Reference: King, TE Jr, and Lee, J.S. Cryptogenic organizinf pneumonia. NEJM. 2022. 386;11:1058-1068