Abstract
Pulmonary Langerhans cell histiocytosis (PLCH) in adults is an uncommon disorder that occurs almost exclusively in smokers. PLCH has no known gender predilection, and the current consensus of its true aetiology is unknown. Lungs may the sole organ involved, however other organs in the body may be involved as well. With the introduction of 2 possible diagnostic categories, it makes PLCH easier and possibly quicker to diagnose. In this report, we present a 34-year-old adult male PLCH case that was negative for the typical immunohistochemistry findings necessary for a "definite" diagnosis but was instead diagnosed based on his florid imaging findings - who also had an unexpected histological finding of a non-specific interstitial pneumonia.