Background <p>The crazy-paving pattern on high-resolution computed tomography (HRCT), defined by ground-glass opacities with superimposed inter- and intralobular septal thickening, is classically associated with pulmonary alveolar proteinosis (PAP) but may also occur in several interstitial lung diseases (ILDs). Distinguishing these entities is important because management strategies differ substantially.</p> Case Presentation <p> A 35-year-old non-smoker presented with progressive exertional dyspnea, dry cough, and inflammatory arthralgia. HRCT of the chest demonstrated bilateral ground-glass opacities with peribronchovascular distribution and areas of crazy-paving, predominantly in the lower lobes. Autoimmune evaluation revealed a positive antinuclear antibody with strong anti-U1-ribonucleoprotein positivity, consistent with mixed connective tissue disease. Bronchoalveolar lavage performed during ILD evaluation yielded milky fluid containing abundant periodic acid–Schiff–positive material, mimicking pulmonary alveolar proteinosis. However, anti–granulocyte–macrophage colony-stimulating factor antibodies were negative and secondary causes were excluded. Multidisciplinary discussion favored connective tissue disease–associated interstitial lung disease with an inflammatory nonspecific interstitial pneumonia pattern. The patient improved with corticosteroids and mycophenolate mofetil therapy.</p> Conclusion <p>This case highlights a diagnostic pitfall in which CTD-associated ILD may mimic PAP with crazy-paving on HRCT and PAS-positive milky BAL. Careful integration of clinical, radiologic, serologic, and bronchoscopic findings is essential to avoid misdiagnosis and inappropriate therapy.</p>