Case Presentation: A 59-year-old female with prior pulmonary embolus and breast cancer presented for outpatient retinal detachment repair. In PACU, O2 saturations were 80%, and she was admitted for further workup. She reported 2 weeks of dyspnea on exertion with productive cough, but denied fever, congestion, chest pain, hemoptysis, dyspnea at rest, weight changes, lower extremity edema, orthopnea, and paroxysmal nocturnal dyspnea. Her rivaroxaban was held pre-operatively, but otherwise she had missed no doses. Additional medications included prior paclitaxel, carboplatin, pembrolizumab, doxorubicin, and cyclophosphamide. She was a never smoker. Family history was noncontributory. Admission vitals were T 36.5°C, HR 71, BP 111/60, RR 18, SpO2 94% on 3L NC. Exam showed bibasilar crackles. CBC and BMP were within normal limits and respiratory pathogen panel was negative. Chest x-ray showed diffuse coarse, hazy ground glass opacities. CTA chest showed diffuse centrilobular ground glass attenuation, most pronounced in mid/upper zones, with traction bronchiectasis at both bases. Pulmonary was consulted and additional history revealed that last chemotherapy was 2 months prior, she worked in an automotive factory with chemicals, and her daughter had adopted a parrot 6 months prior. Bronchoscopy showed 375 nucleated cells, 77% neutrophils, 12% lymphocytes, CD4/CD8 ratio 0.3. Bronchoalveolar acid fast bacilli culture, bacterial culture, respiratory pathogen panel, Pneumocystis jirovecii PCR, lymphocyte markers, hypersensitivity pneumonitis panel, and cytology were negative. Bird Fancier’s Preciptin Panel returned positive for IgG antibodies to parakeet and parrot serum, and she was diagnosed with subacute hypersensitivity pneumonitis secondary to bird exposure. She was started on a prednisone taper with rapid improvement in her oxygenation.
Discussion: Hypersensitivity pneumonitis (HP) is a lung disease that occurs from repeated inhalation of antigens leading to an immune response, presenting with symptoms of dyspnea, cough, fatigue, and fever [1-3]. HP has been linked to a wide set of exposures; however, it is ultimately under-diagnosed given non-specific symptoms and uncertain inciting antigens. Bird Fancier’s Lung is one of the most common types of HP and is primarily related to certain species of birds kept as pets, though there have been reports of association of feather-filled items in the house [3,4]. Work up can present with non-specific findings, however high-resolution CT chest often provides supportive evidence. Bronchoalveolar lavage is the most sensitive tool and often will demonstrate lymphocytosis (>20-25%), elevated mast cells (>1%), and CD4/CD8 ratio < 1. HP is progressive with ongoing antigen exposure, ultimately leading to irreversible lung disease. Thus, it is imperative to diagnose in timely manner to initiate steroids and, more importantly, remove the causative antigen.
Conclusions: Hypersensitivity pneumonitis can present with non-specific respiratory symptoms and can be difficult to diagnose especially in medically complex patients with co-morbid conditions. Bird Fancier’s Lung is one of the most common types of HP. Hospitalists should recognize the importance of obtaining thorough environmental exposure history in patients with respiratory symptoms with unclear history or work up and maintain an acute clinical awareness to prevent progression of disease.
