CRYPTOGENIC ORGANIZING PNEUMONIA DISGUISING AS A LUNG MASS

Abstract

SESSION TITLE: Diffuse Lung Disease 2 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 pm - 02:15 pm INTRODUCTION: The most characteristic presentation of Cryptogenic organizing pneumonia(COP) is multifocal,migratory,relapsing,highly corticosensitive pneumonic opacities.Here we report the case of COP presenting as a solitary lung mass. CASE PRESENTATION: A 76 years old male,smoker with a 40 pack years history of smoking,presented with a 2 month history of breathlessness with fever and productive cough 2 weeks back.The patient reported a 5 kg weight loss.Examination revealed bilateral wheeze.Lab tests were normal.Chest X-ray showed a prominent left hilum.CT chest revealed a soft tissue density mass with irregular margins, measuring 28 x 29 mm in the lingular segment of the left upper lobe, abutting the anterior chest wall.Core biopsy of the left lung mass on pathological examination revealed nodules and plugs containing spindle fibroblasts arranged in myxoid matrix within the alveolar spaces and bronchioles. Lung parenchyma showed evidence of acute on chronic inflammation with mild interstitial widening of the alveolar walls. There was no evidence of granuloma formation or malignancy.Findings were suggestive of COP.The patient was started on oral prednisolone(1 mg/kg/day) which was tapered and stopped.Follow-up chest X-ray and CT scan showed resolution of the soft tissue density previously noted. COP results from incomplete resolution of inflammation in the alveoli, alveolar ducts and terminal and respiratory bronchioles.The diagnosis requires a combination of clinical, radiologic and histopathological(1)expertise. DISCUSSION: COP can at times simulate lung cancer(2)or even coexist with lung cancer(1)due to its sub-acute course and a wide range of clinical presentation.A bilateral non-segmental and patchy sub-pleural distribution is the most common radiologic finding (3).On the contrary lung cancer presents as irregular nodules and masses with evidence of lobulation, speculation, pleural invasion and lymph node metastasis(3).Multiple large(>1 cm)nodules or masses are an uncommon manifestation of COP and are rarely reported.COP with multiple large nodules must be differentiated from other conditions,e.g metastatic lung tumors. This distinction is all the more important as cases of OP due to the direct influence of the tumor on the surrounding lung parenchyma or as direct consequence of chemotherapy and radiotherapy have been well reported in literature. Radiologic similarity at times makes distinction a dilemma based upon radiologic findings alone. Lung biopsy is often required to make a definitive diagnosis.At present the most common treatment options for COP are systemic corticosteroids or surgical resection followed by a period of observation to ensure a sustained treatment response. CONCLUSIONS: COP can present with a variety of radiologic appearance’s making distinction from lung tumors difficult. Clinicians must be aware of this possibility to avoid traumatic and unnecessary procedures. Reference #1: Nakahara Y,Oonishi Y,Takiguchi J,Morimoto A,Matsuokak,Imanishi N,Higashino T,Mimura R, Kamamura T,Mochiduki Y. Nontuberculous mycobacterial lung disease accompanied by organizing pneumonia.Internal Medicine. 2015;54(8):945-51. Reference #2: Zhao F,Yan SX,Wang GF,Wang J,Lu PX,Chen B,Yuan J,Zhang SZ,Wang YX.CT features of focal organizing pneumonia: an analysis of consecutive histopathologically confirmed 45 cases.European journal of radiology. 2014 Jan 1; 83 (1) : 73-8. Reference #3: Lee KS,Kullnig P,Hartman TE,Muller NL.Cryptogenic organizing pneumonia: CT findings in 43 patients AJR.American journal of roentgenology.1994 mar; 162(3): 543-6. DISCLOSURES: No relevant relationships by Yasmin Rahim, source=Web Response