Poor prognosis of pulmonary sarcomatoid carcinoma with KRAS mutation and ALK fusion

Pulmonary sarcomatoid carcinoma (PSC) is a rare subtype of poorly differentiated non-small-cell lung cancer (NSCLC), and no effective treatment is available in clinical practice currently. In the present report, a 61-year-old male patient was hospitalized due to cough, dyspnea, and right chest pain. Computed tomography (CT) showed spot- and piece-shaped shadows. The patient became very weak and had breathing difficulty after preliminary anti-pneumonia treatment with cefoperazone-sulbactam. Physical examination revealed dull sound by percussion and decreased breath sounds in the right lateral lung areas by auscultation. A second CT scan revealed a large amount of pleural effusion, and the patient was diagnosed with bloody pleural effusion through pleural space puncture. Multiple nodular lesions were found in the right pleural cavity under thoracoscopy. PSC was confirmed by biopsy and histopathology in combination with immunohistochemistry (IHC). Single-photon emission CT (SPECT) scan indicated multiple bone metastases. KRAS exon 2 mutation and EML4-ALK fusion were identified in carcinoma tissue by IHC and amplification refractory mutation system (ARMS)-PCR. The patient received one cycle of first-line combination chemotherapy of cisplatin and paclitaxel liposomes. However, the patient did not respond to the platinum-based combination chemotherapy within 3 weeks and was thus administered oral crizotinib instead of chemotherapy. Unfortunately, he still had rapid disease progression and died 2 weeks after the initiation of crizotinib treatment. Collectively, our results suggest that a PSC patient with coexistent KRAS mutation and ALK rearrangement would not benefit from chemotherapy and tyrosine kinase inhibitor (TKI) treatment.