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Program

Internal Medicine

Training Level

Resident PGY 1

Institution

Henry Ford Hospital

Abstract

Introduction: Pneumocystis pneumonia (PCP) is an opportunistic infection caused by Pneumocystis jirovecii (previously Pneumocystis carinii), a yeast-like fungus colonizing up to 20% of immunocompetent adults. Progression from colonization to infection can occur in immunocompromised settings, however differentiating the two can be difficult. Diagnosis traditionally involves three core measures: diffuse bilateral infiltrates on chest x-ray, respiratory symptoms, and identification of Pneumocystis in sputum or bronchoalveolar lavage (BAL). Novel diagnostic modalities including Pneumocystisqualitative PCR and serum B-D-glucan assay (Fungitell) have emerged in clinical practice to assist in diagnosis, however alone cannot truly differentiate colonization from infection. We present an atypical case of PCP, in which the above-mentioned diagnostic tests were used in both diagnosis and management of an HIV uninfected patient with history of prolonged immunosuppressant use for rheumatologic disease.Case:A 50 year-old woman presented to the emergency department with non-productive cough of 10 day duration, associated with subjective fevers and headaches. Past medical history was significant for mixed connective tissue disorder and seronegative SLE, on methotrexate 25 mg weekly, Plaquenil 400 mg daily, Mycophenolate mofetil 1500 mg twice daily, and prednisone 10 mg daily.On admission, she endorsed fevers, fatigue, joint pains, dry cough, headaches, and shortness of breath with minimal exertion. On objective assessment she was febrile to 103 F (39.4 C), tachycardic to 125, and tachypneic to 22 with SpO2 86-88% on room air, improved with 3.0 liters oxygen by nasal cannula. Physical examination revealed acutely distressed woman, with oral thrush, a malar rash, photophobia, bilateral crackles with mild inspiratory rhonchi at lung bases, and regular rhythm tachycardia without murmurs. Laboratory evaluation demonstrated no leukocytosis, and no electrolyte abnormalities; ESR was elevated to 23 mm/Hr, and CRP was elevated to 5.3 mg/dL. Arterial blood gas testing on room air revealed PO2 61.4, PCO2 41.9, pH 7.45, and SpO2 90.9%, with an A-a gradient 36. Blood cultures remained negative. Sputum culture and gram stain was unremarkable, and respiratory virus PCR was negative. Qualitative Pneumocystis jirovecii PCR on sputum sampling was positive, with a normal Fungitell (serum B-D-glucan) level of 31 pg/mL. HIV-testing was negative. Additional infectious workup, including lumbar puncture and 2-D echocardiogram, was unremarkable.Radiographic evaluation included chest x-ray which revealed mild non-specific perihilar and bibasilar opacifications questionable for atelectasis, and follow-up non-contrast chest CT again demonstrated bibasilar band-like opacities concerning for atelectasis.Given her history of immunosuppressive therapy, most notably prolonged use of prednisone, with development of acute exertional dyspnea and hypoxemia and positivePneumocystisqualitative PCR, and otherwise negative infectious work-up, she was diagnosed with PCP and treated with clindamycin, primaquine, and adjuvant prednisone therapy. She demonstrated dramatic improvement and was discharged on hospital day 8, without recurrence of symptoms at one week follow-up.Discussion:Diagnosis of PCP in HIV uninfected patients is based on a combination of clinical, laboratory, and radiographic findings. However, assessing progression of Pneumocystis colonization to infection in HIV uninfected patients is difficult, especially in cases where typical radiographic findings are absent and adjuvant diagnostic modalities, including Fungitell, are normal. History of immunosuppressant use along with evidence of unremitting respiratory distress raises clinical suspicion for PCP in this case, along with positivePneumocystisPCR testing. This case highlights the importance of high clinical suspicion and use of multiple diagnostic modalities in proper diagnosis and management of PCP.

Publication Date

5-2019

An Atypical Case of PCP Pneumonia in a Patient on Chronic Immunosuppression

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