[Adenopathy and mammary carcinoma: It is sometimes in the details that one encounters hypersensitivity pneumonitis!].

Introduction: Hypersensitivity pneumonitis (HP) is an interstitial lung disease due to an immunological reaction to exposure, by inhalation, to a large variety of antigens. The patho-physiological mechanism remains poorly understood. The diagnosis can be challenging and requires a detailed medical history taking especially when the clinical presentation is atypical or when the causal agent remains unknown.