What happened, in summary

A 24-year-old man sought emergency care after coughing up blood. He had experienced a dry cough for 6 months and worsening shortness of breath for about 4 weeks. Initial imaging looked like severe interstitial lung disease, and he was treated first with antibiotics and then corticosteroids, but his breathing continued to worsen and he became dependent on supplemental oxygen.

Lung biopsies eventually showed metastatic carcinoma. Gastroscopy then identified an ulcerated gastric tumor, and biopsy confirmed primary gastric adenocarcinoma with focal signet-ring differentiation. Whole-body imaging showed widespread disease involving the lungs, pleura, mediastinal lymph nodes and bones, establishing Stage IV gastric cancer.

He started cisplatin plus 5-fluorouracil chemotherapy. His breathing improved soon after treatment began, and he no longer needed oxygen. After 2 months, repeat imaging showed a partial response, with regression of the gastric tumor as well as the lung, pleural, mediastinal and skeletal metastases. His clinical respiratory symptoms had also resolved.