SMARCA4 (BRG1)-deficient carcinoma invading the skull base: report of two cases and literature review

Abstract

Introduction and importance: SMARCA4 (BRG1)-deficient carcinomas in the head and neck are a rare and highly aggressive group of malignant tumors. They lack typical clinical and imaging features and are often misdiagnosed. Case presentation: The authors report two male patients with a history of smoking. Case 1 presented with nose bleeding as the first symptom, whereas case 2 presented with headache with blurred vision. Preoperative computed tomography (CT) and MRI suggested a highly aggressive malignant tumor of the head and neck with invasion of the skull base. Case 1 could not be operated on because of the large size of the punctured tumor. Case 2 underwent the surgery. The final pathological diagnosis was SMARCA4 (BRG1)-deficient carcinoma. At the 6-month follow-up, case 1 died. After completing the full course of chemotherapy, case 2 reported progressively worsening headaches and hearing loss. Discussion and conclusion: SMARCA4 (BRG1)-deficient carcinoma in the head and neck is a rare and highly aggressive malignant tumor that is advanced at diagnosis, prone to invasion of adjacent structures, difficult to operate on, and has a poor prognosis. CT and MRI play a vital role in evaluating the size and extent of the tumor, invasion of adjacent structures, and distant metastasis. It provides a significant reference for clinical diagnosis and therapeutic decision-making. Different patients of SMARCA4 (BRG1)-deficient carcinoma in the head and neck respond differently to radiotherapy and chemotherapy. Early use of next-generation sequencing (NGS) or immunohistochemistry(IHC) techniques is helpful in guiding treatment planning.