Double-mutant invasive mucinous adenocarcinoma of the lung in a 32-year-old male patient: A case report

Abstract

BACKGROUND

Invasive mucinous adenocarcinoma of the lung, formerly known as mucinous bronchioloalveolar carcinoma, is a rare category of lung tumors and radiologically characterized by dense pneumonic consolidation, ground-glass opacity, crazy paving, and nodules. However, early pleural effusion is uncommon in this malignancy.

CASE SUMMARY

The case of a 32-year-old male patient who visited our facility with symptoms of cough and gradually aggravated shortness of breath was reported. X-ray examination revealed a massive left hydrothorax. The patient underwent thoracocentesis, and pleural fluid tumor markers, including carcinoembryonic antigen, carbohydrate antigen 19-9, neuron-specific enolase, and cytokeratin 21-1 fragment, were significantly elevated. A similar tendency was observed among the serum tumor markers. After draining the pleural effusion, the patient underwent chest computed tomography, and no obvious mass was found in the lung. Thoracoscopy revealed that the left visceral pleura was covered with nodular, cauliflower-like protrusions of various sizes. These histopathological results suggested cancerous cells, and the immunohistochemical findings were consistent with mucinous adenocarcinoma of pulmonary origin. It tested positive for cytokeratin, cytokeratin 5/6, carcinoembryonic antigen, and thyroid transcription factor-1.

CONCLUSION

The patient was diagnosed with a rare case of lung mucinous adenocarcinoma. Subsequent genetic testing was positive for epidermal growth factor receptor-21 mutations and echinoderm microtubule-associated protein-like 4-lymphoma anaplastic kinase fusion. This prompted treatment with alfatinib and crizotinib.

Keywords: Lung mucinous adenocarcinoma; Hydrothorax; Double mutant; Case report

Core tip: Invasive mucinous adenocarcinoma of the lung is a rare category of lung tumors, radiologically characterized by dense pneumonic consolidation, ground-glass opacity, crazy paving, and nodules. Early pleural effusion is uncommon in this malignancy. Molecularly, invasive mucinous adenocarcinoma has frequent Kirsten rat sarcoma viral oncogene mutations and a lower prevalence of epidermal growth factor receptor and anaplastic lymphoma kinase rearrangements. Here, a rare case of double-mutant invasive mucinous lung adenocarcinoma presenting as a massive malignant pleural effusion in a 32-year-old male patient was reported.