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 Table of Contents  
Year : 2018  |  Volume : 20  |  Issue : 2  |  Page : 165-167

A rare case of H1N1 influenza-associated organizing pneumonia

1 Department of Pulmonary Medicine, INHS Asvini, Mumbai, Maharashtra, India
2 Department of Rheumatology, INHS Asvini, Mumbai, Maharashtra, India
3 Department of Radiology, INHS Asvini, Mumbai, Maharashtra, India

Date of Submission11-Mar-2018
Date of Acceptance17-Aug-2018
Date of Web Publication10-Jan-2019

Correspondence Address:
Surg Lt Manjit S Tendolkar
B-3/2, SBI Colony, Sector 13, Nerul, Mumbai - 400 706, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jmms.jmms_15_18

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H1N1 influenza A was responsible for global pandemic in 2009. Since then H1N1 continues to be responsible for epidemics frequently. H1N1 influenza causing organizing pneumonia (OP) is extremely rare, and only 6 cases have been reported till date. Here, we report a case of H1N1 presenting as an OP. The significance of diagnosing OP in appropriate clinical and radiological setting is being highlighted along with its prompt response to treatment.

Keywords: Acute febrile illness, H1N1, organizing pneumonia

How to cite this article:
Tendolkar MS, Tyagi R, Mullick G, Chauhan V. A rare case of H1N1 influenza-associated organizing pneumonia. J Mar Med Soc 2018;20:165-7

How to cite this URL:
Tendolkar MS, Tyagi R, Mullick G, Chauhan V. A rare case of H1N1 influenza-associated organizing pneumonia. J Mar Med Soc [serial online] 2018 [cited 2022 Aug 13];20:165-7. Available from: https://www.marinemedicalsociety.in/text.asp?2018/20/2/165/249754

  Introduction Top

Epidemics of H1N1 are common and cases often present with a viral pneumonia which responds to antivirals and supportive care. Here, we present a rare case of interstitial pneumonia in the form of an organizing pneumonia (OP) associated with H1N1 infection. The uniqueness of this presentation necessitates specific treatment and hence needs to be considered in pneumonias not responding to conventional management. Till date, only six cases have been reported for H1N1 presenting as OP.

  Case Report Top

In September 2017, a 20-year-old serving sailor presented with a history of flu-like illness during an influenza epidemic. The patient was apparently alright 48 h before presenting to the emergency department. He was symptomatic with a high-grade fever which was continuous and associated with chills along with sore throat and body ache. Respiratory system examination was unremarkable. Blood counts revealed leukopenia with lymphocytosis. Liver enzymes, serum creatinine, and urine examinations were within normal limits. He had no complaints of cough, breathlessness, rhinitis, and burning micturition. Based on this clinical history, he was managed conservatively as a flu-like illness. Over 4 days of admission, fever persisted, and the patient started developing breathlessness and left-sided chest pain. Chest X-ray revealed bilateral lower zone consolidation. He was managed with injection Amoxicillin + Clavulanate 1.2 g intravenous 12th hourly and Azithromycin 500 mg OD for 5 days. His throat swab tested positive for H1N1, and he was managed with oseltamivir. Over 5 days course of Oseltamivir 150 mg 12th hourly, his fever showed improving trend and blood counts normalized, but patient continued to deteriorate in the form of progressive breathlessness along with hypoxemia (arterial blood gas: pH 7.50, PaCO2: 32 mmHg, PaO2: 62 mmHg, HCO3: 23.5 mmol/l, and SO2: 92%). The patient underwent an high-resolution computed tomography (HRCT) chest which revealed bilateral lower lobe peripheral consolidation with central areas of ground glass opacities [Figure 1]. To rule out fungal infection, serum galactomannan titers were tested which were negative. Since the patient was immunocompetent with no comorbidities, based on supportive clinical history and radiological findings, he was suspected to have OP and was managed with steroids. There was a dramatic improvement to the treatment as his hypoxemia and breathlessness improved within a day. His general condition improved and he was discharged on steroids. HRCT chest was repeated after 1 month which showed complete resolution of the consolidation [Figure 2]. He continues to follow-up in pulmonology outpatient department where he is watched for a recurrence as the steroids are being tapered.
Figure 1: Reversed halo sign (Atoll Sign)

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Figure 2: Resolution of organizing pneumonia

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  Discussion Top

OP is an interstitial lung disease which is characterized by a disordered inflammatory response. It can be secondary or idiopathic, wherein it is termed as cryptogenic OP. In our case, it was secondary to H1N1 influenza virus.

Till date, only six cases of H1N1 influenza leading to OP have been reported [Table 1].[1],[2],[3],[4],[5]
Table 1: Cases of H1N1 associated Organizing Pneumonia documented in literature till 2017

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OP is confirmed by a lung biopsy. An open lung biopsy remains the preferred modality for diagnosis. However, in our case, a presumptive diagnosis of OP was made based on clinical history and radiological findings. Our patient was an immune competent host, and fungal infection was ruled out by testing beta-galactomannan. While the diagnosis could be confirmed by biopsy, the patient was started on steroids. The prompt clinical improvement of the patient to steroids subsequently confirmed the diagnosis of OP. Furthermore, the clinical status of the patient did not permit a biopsy as he was too tachypneic to tolerate the procedure.

HRCT finding of a “reverse halo” sign (atoll sign) has been shown to be highly specific for diagnosing OP in the relevant clinical setting.[6] Infective differential diagnoses of “reverse halo” sign include invasive fungal infection, bacterial pneumonia, and tuberculosis. Noninfective differential diagnoses include OP, sarcoidosis, nonspecific interstitial pneumonia, lipoid pneumonia, granulomatosis polyangiitis, and pulmonary embolism. Other documented causes are malignancies and radiotherapy. Since our patient was an immunocompetent host with a short clinical history, our differentials were narrowed down to bacterial pneumonia and OP. Bacterial pneumonia was unlikely since his serum procalcitonin was normal and the patient had completed a course of broad-spectrum antibiotics. His underlying infectious etiology was confirmed by H1N1 polymerase chain reaction test and treated with oseltamivir. The infection was improving as was suggested by subsiding fever and improving blood counts. However, progressive breathlessness and hypoxemia along with the characteristic radiological picture were accounted for by OP. Moreover, this was further confirmed by the immediate response to steroids.[7]

The patient is being monitored for relapse of OP since it is frequently described.[8]

  Conclusion Top

We wish to highlight the significance of clinico-radiological diagnosing OP, wherein a biopsy may be spared if the clinical condition precludes to the procedure. OP remains a potential squeal to H1N1 and must be considered in refractory cases as the appropriate treatment can be lifesaving.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Staud R, Ramos LG. Influenza A-associated bronchiolitis obliterans organizing pneumonia mimicking Wegener's granulomatosis. Rheumatol Int 2001;20:125-8.  Back to cited text no. 1
Dolin R, Mark EJ. Case 36-2001. Massachusetts Medical Society. N Engl J Med 2001;345:1558-65.   Back to cited text no. 2
Torrego A, Pajares V, Mola A, Lerma E, Franquet T. Influenza A (H1N1) organising pneumonia. BMJ Case Rep 2010;2010. pii: bcr1220092531.  Back to cited text no. 3
Cornejo R, Llanos O, Fernández C, Carlos Díaz J, Cardemil G, Salguero J, et al. Organizing pneumonia in patients with severe respiratory failure due to novel A (H1N1) influenza. BMJ Case Rep 2010;2010. pii: bcr0220102708.  Back to cited text no. 4
Otto C, Huzly D, Kemna L, Hüttel A, Benk C, Rieg S, et al. Acute fibrinous and organizing pneumonia associated with influenza A/H1N1 pneumonia after lung transplantation. BMC Pulm Med 2013;13:30.  Back to cited text no. 5
Kim SJ, Lee KS, Ryu YH, Yoon YC, Choe KO, Kim TS, et al. Reversed halo sign on high-resolution CT of cryptogenic organizing pneumonia: Diagnostic implications. AJR Am J Roentgenol 2003;180:1251-4.  Back to cited text no. 6
Cordier JF. Rare diseases bullet 8: Organising pneumonia. Thorax 2000;55:318-28.  Back to cited text no. 7
Lazor R, Vandevenne A, Pelletier A, Leclerc P, Court-Fortune I, Cordier JF, et al. Cryptogenic organizing pneumonia. Characteristics of relapses in a series of 48 patients. The groupe d'etudes et de recherche sur les maladles “Orphelines” pulmonaires (GERM“O”P). Am J Respir Crit Care Med 2000;162:571-7.  Back to cited text no. 8


  [Figure 1], [Figure 2]

  [Table 1]


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