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).