ISSN: 2578-4625
Authors: Bajaj A*
Thoracic SMARCA4-deficient undifferentiated tumour emerges as a distinct, aggressive neoplasm of thoracic cavity delineating unique morphological, phenotypic and molecular features associated with rapid clinical progression and inferior overall survival. Tumefaction is associated with definitive molecular modifications confined to SMARCA4 gene, especially within ATPase subunits of SWI/SNF chromatin modifying complex. Neoplasm manifests as an enlarged tumefaction compressing adjacent thoracic viscera with frequent pulmonary and mediastina involvement. Cytological smears demonstrate cellular smears comprised of singular cells or clusters and sheets of non-cohesive Tumour cells configuring glandular structures or papillary articulations. Tumefaction is comprised of sheets of non-cohesive, monomorphic, spherical cells pervaded with variegated nuclei and prominent nucleoli. Thoracic SMARCA4-deficient undifferentiated tumour mandates discernment of cogent features as foci of rhomboid or poorly differentiated tumour cells, significant loss of expression of SMARCA4 and SMARCA2 and focal or diffuse immune reactivity to minimally two biomarkers as SOX2, CD34 or SALL4. Tumour cells appear immune reactive to synaptophysin, chromogranin and stem cell markers as CD34, SALL4 and SOX2. Tumefaction is immune non-reactive to cytokeratin, Claudin 4, POU2F3 and exhibits a concurrent loss of expression of BRG1 and BRM. Thoracic SMARCA4-deficient undifferentiated tumour requires demarcation from diverse vascular tumours, epithelioid angiosarcoma, epithelioid sarcoma, liposarcoma, gastrointestinal stromal tumour, malignant melanoma, NUT pulmonary carcinoma, malignant peripheral nerve sheath tumour, large cell lymphoma, germ cell tumours, rhabdomyosarcoma, Ewing’s sarcoma, CIC-DUX4 sarcoma, various undifferentiated sarcomas, mesothelioma and anaplastic or undifferentiated carcinomas devoid of keratin expression. Thoracic SMARCA4- deficient undifferentiated tumour may be challenging to alleviate as therapeutic targets appear difficult to obtain and neoplasm is associated with lymphatic dissemination.
Keywords: Thoracic tumour; deficient SMARCA4; immune reactive SOX2; CD34; SALL4
