Atypical Radiologic Presentation of Pneumocystis jiroveci Pneumonia in an HIV Positive Patient

Abstract

INTRODUCTION: Pneumocystis jiroveci pneumonia (PJP) is a common respiratory infection in patients with HIV. On CT it typically presents as bilateral, symmetrical ground-glass attenuation. Interstitial patterns, pulmonary nodules, cavitary lesions and pleural effusions have also been reported. The reverse halo, or Atoll's, sign, which is a radiographic pattern characterized by a focal circular area of ground-glass attenuation surrounded by a crescent or ring of consolidation, has been reported in various diseases including cryptogenic organizing pneumonia. It has rarely been reported in PJP. We present a case of PJP in an HIV-positive patient with atypical radiologic features including the reverse halo sign and pulmonary nodules. CASE PRESENTATION: A 61 year-old woman with AIDS presented with weakness and dyspnea on exertion for 2 weeks. She denied having a cough, sputum, hemoptysis, fever, night sweats and history of tuberculosis. She had an episode of PJP in 2009 and had no subsequent pulmonary illnesses. She was non-compliant with HAART and had restarted HAART 1 month prior to current admission. On admission, her temperature was 100.6°F, pulse 108 bpm, normotensive, respiratory rate 18, and oxygen saturation 96% on room air. On pulmonary exam, there were mild left lower lobe rales without wheezing and good air movement bilaterally. All other physical exam findings were within normal limits. Labs included a WBC count of 3.2, LDH of 499, CD4 was 0. Cryptococcal antigen and QuantiFERON were negative. Chest x-ray showed bilateral interstitial infiltrates. Due to a somewhat atypical appearance on chest x-ray and normal LDH, CT scan of the chest was performed. It showed bilateral interstitial disease, lung nodules, and the reverse halo sign, which were seen in a predominantly peripheral location. Bronchoscopy with BAL and transbronchial biopsies revealed Pneumocystis jirovecii. The patient improved significantly on Sulfamethoxazole/Trimethoprim and corticosteroids. A follow-up CT 4 weeks later revealed marked improvement in the parenchymal changes, though new cystic changes were now seen in the right lung. DISCUSSION: To our knowledge, the reverse halo sign has only been reported in one other case of PJP. Although IRIS could have accounted for the atypical presentation in this patient who was recently started on HAART, the patient's CD4 count was 0 and she was noncompliant with therapy, making IRIS unlikely. CONCLUSIONS: This case illustrates an atypical presentation of PJP with the reverse halo sign and pulmonary nodules seen on chest CT, with the LDH level within the normal limits.