SMARCA4-deficient thoracic sarcoma revealed by metastasis to the small intestine: a diagnostic dilemma

Small Intestine Metastasis Leads to the Diagnosis of Thoracic SMARCA4-Deficient Undifferentiated Tumor: A Case Report

SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is a rare and aggressive malignancy characterized by the loss of SMARCA4 protein expression. It typically affects middle-aged male smokers and has a poor prognosis due to its rapid progression and metastatic potential. This case report presents a 73-year-old male diagnosed with a thoracic SMARCA4-UT. Initially diagnosed with stage IVA non-small cell lung cancer, the patient underwent brain tumor resection, radiation, and chemo-immunotherapy. Treatment was halted due to immune-related adverse events. During treatment, a progressing small intestine tumor was discovered, resected, and identified as SMARCA4-UT metastasis through immunohistochemistry, leading to a revised diagnosis of SMARCA4-UT with brain and small intestine metastases. The patient received multimodal treatment, including surgery, radiation, and chemo-immunotherapy. The small intestine metastasis showed resistance to systemic therapy, necessitating surgical intervention. This case highlights the diagnostic challenges and treatment complexities of SMARCA4-UT, emphasizing the importance of comprehensive diagnostic workup and personalized treatment strategies. It demonstrates the potential efficacy of combining systemic therapy with targeted interventions for oligoprogressive disease. The patient's progression-free survival at approximately two years post-diagnosis underscores the need for further research into optimal management strategies for this rare tumor.

Delayed Diagnosis of SMARCA4-Deficient Undifferentiated Tumor in a Heavy Smoker Male Patient: Discovered Through Bone Sampling, with Extensive Distant Metastases and Concurrent Granulomatous Disease, Leading to Patient Fatality

Background. SMARCA4-deficient undifferentiated tumors are rare and pose a diagnostic challenge. This study delves into the intricate diagnostic terrain of SMARCA4-deficient undifferentiated tumors, providing insights into their diverse clinical presentations and diagnostic approaches. Case Presentation. A 69-year-old heavy-smoker man with adalimumab-treated rheumatoid arthritis presented with multiple lesions. A CT scan revealed a spiculated lung mass, enlarged mediastinal lymph nodes, and hepatic lesions. A whole-body FDG-PET/CT scan revealed heterogeneous hypermetabolic lesions in the lung, liver, and bone. Initial two core needle liver biopsies and a left upper lobe lung wedge resection initially indicated steatohepatitis and granulomatous formation with no evidence of malignancy. Several months later, the patient returned with left-sided flank pain and significant weight loss. CT scan identified a thigh mass, adrenal lesion, and extensive multiple skeletal lesions. A biopsy of the thigh mass revealed an extensively necrotic, epithelioid-to-spindled cell neoplasm with positive staining for pan keratin, focal staining for CD56, and a loss of nuclear expression of SMARCA4. A final diagnosis of SMARCA4-deficient undifferentiated tumor was rendered. Unfortunately, the patient's condition deteriorated, and he died a few weeks after receiving the final diagnosis. Conclusion. SMARCA4-deficient undifferentiated tumors have emerged as recent subjects of medical study, distinguished by their unique morphology and SMARCA4-deficient immunohistochemistry. These tumors present diverse clinical manifestations, affecting multiple organ systems. This report underscores the diagnostic complexities associated with complex clinical presentation and highlights the importance of multidisciplinary collaboration in addressing challenging clinical scenarios, particularly among heavy smoker male patients and intricate radiological presentations.

A Case Report of SMARCA4-Deficient Thoracic Sarcoma: A Rare and Aggressive Disease With a Grim Prognosis

SMARCA4-deficient thoracic sarcoma (DTS) is a rare malignancy defined by inactivating SMARCA4 mutations leading to protein loss. It was recently described as an aggressive disease with a dismal prognosis, mostly affecting young men with a history of heavy smoking. Histologically, SMARCA4-DTS is a poorly differentiated tumor with rhabdoid or epithelioid features that can be distinguished from other soft tissue, and thoracic sarcomas by a higher tumor mutation burden (TMB) and the presence of smoking signatures, including KRAS, STK11, and KEAP1 mutations. Currently, there is no approved treatment for SMARCA4-DTS, which is known to be chemo-resistant, but more recent studies have shown some effectiveness with immune checkpoint inhibitors. We report the case of a 42-year-old man with a family history of cancer who was admitted to the hospital with acute respiratory distress and superior vena cava syndrome. He had been experiencing thoracic pain, dry cough, dyspnea, fatigue, and unintentional weight loss for a month. Imaging revealed multiple masses and lymph nodes in the chest, as well as pleural effusion. PET scan showed widespread metastases. A cervical lymph node biopsy confirmed the diagnosis of SMARCA4-deficient thoracic sarcoma. Unfortunately, his general condition did not allow an aggressive treatment. He was started on Pazopanib 800mg per day, but deteriorated rapidly and passed away. This report highlights the aggressive nature and unfavorable prognosis associated with SMARCA4-deficient thoracic sarcoma. Accurate diagnosis of this entity can be challenging due to its unique marker expression and unfamiliar histological features. Currently, there are no established treatment strategies for this condition; however, recent studies have shown promising results with immune checkpoint inhibitors and targeted therapies. Further research is necessary to identify the most effective treatment approaches for SMARCA4-DTS.

Thoracic SMARCA4-deficient undifferentiated tumor

Thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is a recently described smoking-related malignancy. The pathogenesis of SMARCA4-UT is the mutational inactivation and loss of expression of a subunit encoding the mammalian switch/sucrose nonfermenting ATPase-dependent chromatin remodeling complex (which can be mobilized using adenosine triphosphate hydrolysis nucleosomes and regulate other cellular processes including development, differentiation, proliferation, and apoptosis), in particular SMARCA4 and SMARCA2. The dynamic activity of this complex plays an important role in regulating the activation and repression of gene expression programs. SMARCA4-UT exhibits morphological features similar to the malignant rhabdoid tumor (MRT), small cell carcinoma of the ovary of the hypercalcemic type (SCCOHT), and INI1-deficient tumor, but SMARCA4-UT differs from SCCOHT and MRT from a genomic perspective. SMARCA4-UT mainly involves the mediastinum and lung parenchyma, and appears as a large infiltrative mass that easily compresses surrounding tissues. At present, chemotherapy is a common treatment, but its efficacy is not clear. Moreover, the inhibitor of the enhancer of zeste homolog 2 showed promising efficacy in some patients with SMARCA4-UT. This study aimed to review the clinical characteristics, diagnosis, treatment, and prognosis of SMARCA4-UT.