Source 1: Subject matter experts
Histology--Lung: Is there a better code for SMARCA4-deficient malignant neoplasms than 8000/3 that could be used especially given its aggressive nature? This term is not included in the Lung Solid Tumor Rules or ICD-O-3.1 and 3.2. See Discussion.
Per Mayo consulting pathologist, the final diagnosis on this right lung biopsy is: SMARCA4-deficient malignant neoplasm (see Comment). Comment: Sections show a poorly-differentiated malignant neoplasm without any apparent glandular, squamous, or stromal differentiation. The tumor near totally replaces the underlying lung tissue without recognizable underlying alveolar parenchyma. Immunohistochemical stains performed at Mayo Clinic (Oscar keratin, INSM1, NUT, S100, desmin and BRG1 protein encoded by SMARCA4 gene) demonstrate that the malignant cells are positive for Oscar keratin (rare cells only), synaptophysin (weak/patchy) and p63 (focal) while negative for the remaining antibodies tested. Of note, SMARCA4 stain is negative in the tumor cells. Thus, this tumor can be categorized as a SMARCA4-deficient malignant neoplasm, which is known to be an aggressive malignancy, likely represent a SMARCA4-deficient thoracic sarcoma, a recently described entity. SMARCA4-deficient carcinomas in the lung have been reported to be mostly adenocarcinomas or squamous cell carcinomas, which would not fit for this case. Please refer to a paper published by our group (Sauter JL et al. Mod Pathol 2017;30:1422-32.
Assign code 8020/3. SMARCA4-deficient malignant neoplasms are newly identified. WHO has not proposed an ICD-O code as of yet. Our pathology experts suggest coding to undifferentiated carcinoma until they are better classified.