BACKGROUND Carcinomatous lymphangitis of the lung accounts for 6-8% of lung's metastases. There are evidence that it can be a treatable condition with an impact on progression of dyspnea and radiographic lesions, and survival improvement. Two cases are reported, with the aim of increase the clinical suspicion at compatible cases. METHODS Case 1: woman 32 years old. Progressive dyspnea and cough two weeks ago, without antibiotic response. Tachypnea, increase of respiratory work, basal crackles. Respiratory failure. Radiography: basal alveolointerstitial opacities. Treatment for severe community-acquired pneumonia is started. She evolves unfavorably, with need of MRA and fatal outcome. Case 2: woman 46 years old. Progressive dyspnea and cough from one week ago. Tachypnea, diffuse crackles. Respiratory failure. Radiography: diffuse nodular-interstitialradiopacity, with radiopacy lesion in right apex. HRCT: nodular thickening of interlobular septum and peribrochovascular interstitial. Treatment for tuberculosis of the lung is started. She evolves unfavorably, with need of MRA and fatal outcome. In both cases a lung biopsy was performed, diagnosing carcinomatous lymphangitis. CONCLUSIONS Two cases are reported, with acute afebrilepneumopathyin young patients, whose manifestations guided to treatment of respiratory infection, and evolved quickly to refractory hypoxemic respiratory failure with need of MRA and fatal outcome. CONCLUSIONS Carcinomatous lymphangitis of the lung should be included as a differential diagnosis of cases of acute lung pathology, especially when there was an unfavorable evolution under antibiotics or have excluded more common etiologies.