MAC CALLING THE COP: ORGANIZING PNEUMONIA SECONDARY TO MYCOBACTERIUM AVIUM COMPLEX INFECTION

Abstract

TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: Organizing pneumonia (OP) is an inflammatory lung disease involving the distal bronchioles, respiratory bronchioles, bronchiolar ducts & alveoli. OP may be cryptogenic (COP) or secondary to several factors such as drugs, infections, radiation therapy, malignancy or CTD.Mycobacterium Avium Complex (MAC) pulmonary infection is a challenging entity & diagnosis relies on the integration of clinical, radiological, microbiological & pathological results. The clinical course is heterogenous, ranging from asymptomatic cases to patients with refractory disease associated with considerable morbidity and mortality. CASE PRESENTATION: A 44-year-old female with history of COPD, DM 2, alcoholic cirrhosis, tobacco & opioid use disorder presented with worsening SOB & dry cough for a week. She was treated a year ago with 3 months of steroid therapy for COP with complete clinical and physiologic improvement and normalization of the chest film.She endorsed subjective fever & myalgias but denied hemoptysis, night sweats, weight loss, rashes, joint swelling or pain, sick contacts, recent travel & occupational exposure. Vitals were significant for fever, hypoxia, tachypnea & tachycardia. Physical exam revealed crackles in bilateral mid to lower lung fields. Laboratory results showed leukocytosis & thrombocytopenia. Serum chemistry was notable for elevated lactate but normal procalcitonin, cardiac enzymes & BNP. COVID19 PCR nasal swabs x 2 were negative. CTA showed patchy bilateral consolidations with surrounding ground glass opacities throughout lung fields & no evidence of PE. Patient was started on broad spectrum antibiotics. Infectious & Rheumatological work up turned out to be negative. Given negligible improvement & previous history of COP, she underwent VATS with wedge biopsy & histopathology confirmed florid organizing pneumonia. Glucocorticoid therapy was initiated. At 8 weeks, her tissue culture revealed the presence of MAC. Due to unfavorable clinical response to steroid therapy alone, it was decided to start Rifabutin, Ethambutol & Azithromycin to treat MAC pulmonary infection causing secondary OP. Patient showed clinical improvement & glucocorticoids were gradually tapered. Patient was referred to respiratory rehabilitation & scheduled for follow up at outpatient clinic. DISCUSSION: MAC pulmonary infection & secondary OP association has been rarely reported in the literature. OP is believed to be a consequence of alveolar epithelial injury. Both MAC pulmonary infection & OP have increased cytokine production leading to the inflammation suggesting a common pathway. Therefore, it may be possible for MAC to trigger an OP reaction. CONCLUSIONS: We recommend a systematic assessment of potential etiological agents triggering, what is considered to be COP. Further studies are warranted to establish a causal relationship between MAC & OP thus representing another manifestation of NTM-PD. REFERENCE #1: Cordier J-F. Cryptogenic organising pneumonia. Eur Respir J 2006;28:422–46 REFERENCE #2: Griffith DE, Aksamit T, Brown-Elliott BA, et al. An official ATS/IDSA statement: diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases. Am J Respir Crit Care Med 2007;175:367–416 REFERENCE #3: Carre PC, King TE, Mortensen R, et al. Cryptogenic organizing pneumonia: increased expression of interleukin-8 and fibronectin genes by alveolar macrophages. Am J Respir Cell Mol Biol 1994;10:100–5 DISCLOSURES: No relevant relationships by Muhammad Ahsan, source=Web Response No relevant relationships by Kristin Fless, source=Web Response No relevant relationships by Thomas Ng, source=Web Response No relevant relationships by ARCHANA SREEKANTAN NAIR, source=Web Response