Rare case of Thoracic Endometriosis reported in NEJM

According to history, a 26-year-old woman presented to the emergency department with an episode of coughing up blood. During the previous 4 years, she had had intermittent episodes of small-volume hemoptysis coinciding with her menstrual cycles. She had no other abdominal or pelvic symptoms. Her oxygen saturation was 100% while she was breathing ambient air. On physical examination, the lungs were clear. Noncontrast computed tomography (CT) of the chest on the third day of her menstrual cycle showed an 11-mm ground-glass, cavitary nodule in the right lower lobe (Panel A, arrow). A video-assisted thoracoscopic wedge resection was performed, and a reddish-brown lesion was identified. Histopathological analysis revealed endometrial glands and stroma (Panel B), which confirmed a diagnosis of thoracic endometriosis. Catamenial hemoptysis is a rare manifestation of thoracic endometriosis, and both CT and histopathological examination are important for diagnosis. At a follow-up visit 2 years after resection, the patient was symptom-free.