Dyspnea and crazy paving on computed tomography: Is it easy to make the diagnosis?

We present the case of a woman aged 76 years, never smoker, with known exposure to mold, presented with worsening dyspnea and mild fatigue over the past six months. Chest imaging was consistent with ‘crazy paving’ pattern, while spirometry revealed a restrictive pattern. The differential diagnosis included lower respiratory tract infection, systemic autoimmune disease with pulmonary involvement, hypersensitivity pneumonitis, and pulmonary alveolar proteinosis (PAP). The patient was initially diagnosed as PAP due to an indicative periodic-acid-Schiff stain from the bronchoalveolar lavage cytology. However, repetition of the test did not reveal the same results. HP was also excluded, as the patient was deteriorating despite avoidance from the suspected antigen (mold). After exclusion of the other diagnoses, the patient started treatment as unclassifiable Interstitial Lung Disease (uILD). The aim of this case presentation is to highlight the interesting differential diagnosis in a patient with crazy paving pattern on chest imaging, which is broad and can be challenging for the clinician.