Cutaneous metastasis of SMARCA4-deficient thoracic sarcoma: A diagnostic dilemma with therapeutic implications

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.

Primary cutaneous SMARCA4-deficient undifferentiated malignant neoplasm: A rare case report and literature review

Primary cutaneous SMARCA4-deficient undifferentiated malignant neoplasm (SD-UMN) is a rare and recently described entity characterized by the loss of expression of the SMARCA4 (BRG1) protein, which is involved in chromatin remodeling. SD-UMN presents a diagnostic challenge due to its rarity and unique histopathological and immunohistochemical features. In this report, we present a case of primary cutaneous SD-UMN in a 67-year-old man who presented with a rapidly growing, ulcerated, and bleeding nodule on his right cheek. Histopathological examination revealed a highly cellular dermal tumor consisting of pleomorphic epithelioid cells with prominent mitotic figures and necrosis, lacking any morphological evidence of differentiation. Immunohistochemical analysis showed a complete loss of SMARCA4 and SMARCA2 expression, while INI-1 expression remained intact. p53 was diffusely expressed, and p16 was completely absent. In addition, a range of markers, including high-molecular-weight cytokeratin, p63, SOX10, INSM1, MCPyV, NKX2.2, CD99, CDX2, CD56, ERG, NUT, desmin, androgen receptor, chromogranin, CD34, and CD43 were all negative. To date, only two cases of primary cutaneous SMARCA4-deficient undifferentiated tumors have been reported in the literature. Therefore, this case report adds to the limited body of knowledge on the clinical and histopathological features of this novel entity. The report highlights the importance of considering SD-UMN in the differential diagnosis of undifferentiated cutaneous tumors.

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.

Primary cutaneous SMARCA4-deficient undifferentiated malignant neoplasm: first two cases with clinicopathologic and molecular comparison to eight visceral counterparts

SMARCA4-deficient undifferentiated malignant neoplasms (SD-UMN) comprise a group of aggressive tumors with epithelioid morphology that are characterized by loss of function of SMARCA4, a component of the SWI/SNF chromatin remodeling complex. SD-UMN was first recognized in the thoracic cavity but is now appreciated to occur at multiple anatomic sites. A notable exception has been skin. Here we report the first two cases of primary cutaneous SD-UMN and compare their features to a cohort of eight visceral cases arising in lung, gastrointestinal tract, and gallbladder. Evidence for a bona fide cutaneous origin included extensive clinical, radiologic, and serologic analyses that failed to identify a metastatic source as well as the molecular identification of a UV-associated mutational pattern. The cutaneous cases showed strikingly similar morphologic, immunohistochemical, and molecular features to the visceral cases, strongly suggesting that they belong to this family of tumors. In addition to biallelic inactivation of SMARCA4, both cutaneous tumors also showed biallelic inactivation of TP53 and CDKN2A, findings which also appear common in visceral cases. One patient died of disease at 18 months after diagnosis, consistent with the aggressive nature of this tumor. Our results expand the anatomic spectrum of SD-UMN, adding this entity to an already challenging differential diagnosis that includes melanoma, squamous cell carcinoma, Merkel cell carcinoma, epithelioid sarcoma, and others. Given the potentially aggressive nature of SD-UMN, the timely and accurate diagnosis of this entity may have implications for prognosis and therapy.

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

SMARCA4-deficient thoracic sarcoma (SMARCA4-DTS) is a recently identified aggressive subtype of sarcoma. We present the case of a 44-year-old man who underwent a surgery for a perforated small intestine. Compued tomography scan revealed a tissular mediastino–pulmonary mass.

Histopathological examination of the intestinal mass shown a malignant tumour with a typical epithelioid and rhabdoid cells, numerous mitoses and large necrosis. A large panel of immunohistochemistry revealed loss of SMARCA4 and SMARCA2 and allowed the diagnosis of SMARCA4-DTS. It is important to consider SMARCA4-deficient thoracic sarcoma in the differential diagnosis of tumours showing suggestive morphologic features in patients of all ages, especially in the case of metastasis associated with thoracic mass.