Abstract
Thoracic SMARCA4 -deficient undifferentiated tumors are rare, with poor prognosis. A 73-year-old man presented to our hospital with dyspnea. Computed tomography-guided biopsy revealed aSMARCA4 -deficient undifferentiated tumor. The patient was treated with combination ipilimumab-nivolumab. The tumor reduced in size after two courses.
Keywords: SMARCA4 , undifferentiated tumors, case report
Introduction
Thoracic SMARCA4 -deficient undifferentiated tumors are high-grade tumors of the thoracic region in adults, characterized by an anaplastic or rhabdoid phenotype and defective SMARCA4 expression. These tumors occur more commonly in young to middle-aged men with a history of heavy smoking and are often centered in the mediastinum or hilar regions. The prognosis is poor, with a median survival of 4–7 months due to poor response to treatment and high-grade malignancy.1,2 In general, cytotoxic chemotherapy is not effective; however, case reports of significant response to immune checkpoint inhibitors have been published.3–6Combination ipilimumab-nivolumab reportedly significantly prolongs overall survival (OS) compared with chemotherapy in patients wtih non-small cell lung cancer,7 although no cases ofSMARCA4 -deficient undifferentiated tumors treated with combination ipilimumab-nivolumab have been reported.
Case presentation
A 73-year-old man with a 10-year history of diabetes and heart failure and a 50 pack-year smoking history underwent computed tomography (CT) in November of year X-1 and was suspected to have lung cancer. Subsequently, the patient’s respiratory distress worsened on approximately January X and he visited our hospital on January 18th the same year, and the following vital signs were documented: oxygen saturation (SpO2, 95%); respiratory rate, 16 breaths/min; blood pressure, 110/83 mmHg; and heart rate, 122 beats/min. Endobronchial ultrasound-guided transbronchial needle aspiration was performed on lymph nodes #7 and #4R with a 21-gauge puncture needle, although the cytology results were inconclusive. CT-guided biopsy was performed for metastatic lesions in the right adrenal gland with an 18-gauge puncture needle. Histopathological examination revealed diffuse sheets of proliferating and highly atypical epithelioid cells with coagulation necrosis.
The tumor cells were relatively monotonous, with eosinophilic cytoplasm, vesicular chromatin, 1–2 prominent nucleoli, and a partial rhabdoid appearance (Figure 1).