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Cytopathologic and histopathologic characteristics of SMARCB1 deficient neoplasm and correlation with molecular and
Sandra Ixchel Sanchez1, Christina Adams1, Peter Illei1
1Department of Pathology, The Johns Hopkins University School of Medicine and the Johns Hopkins Hospital, Baltimore, MD, United States.
Introduction:
SMARCB1 deficient neoplasm is an aggressive and heterogeneous group of neoplasms. The morphology of the neoplasm is highly variable. Recent clinical trials show that targeted therapy with EZH2 inhibitor tazemetostat can improve patients' survival. Thus, it is important to recognize the entity for appropriate clinical management.
Material And Methods:
The pathology archive was searched over 10-year period for cases with diagnosis of SMARCB1 deficient neoplasm and aberrant expression of SMARCB1 (INI-1). Cyto- and histomorphology, immunohistochemistry (IHC) and molecular findings were characterized.
Results:
54 cases with complete loss of SMARCB1 (INI-1) on IHC staining were identified, including 5 serous fluids, 10 fine needle aspirations (FNA), 18 biopsy cores and 21 surgical resections. The median age of patients was 35.8 years, ranging from 14 days to 87 years. The female to male ratio was 1.07:1.00. The most involved anatomic sites in descending order were: head and neck (n = 14), CNS (n = 11), lymph node (n = 8), thorax/lung (n = 6), liver (n = 5) and others (n = 10). In addition to published morphology patterns, characteristic cytomorphology included phenotypic features of poorly differentiated carcinoma with pleomorphic tumor cells, basaloid, rhabdoid or epithelioid sarcomas. These tumors had frequently positive cytokeratin stains. Complex genetic abnormalities were identified, including aberrant SMARCB1/INI-1, PIK3C2B, RAF, MAP3K14, FBXO11 and others. 10 cases of partial loss of SMARCB1 (/INI-1) were also included.
Conclusions:
The ancillary testing of SMARCB1 (INI-1) should be considered in a subset of patients whose tumor demonstrates bizarre cytomorphology, especially in poorly differentiated or markedly pleomorphic tumors. The cytological recognition is critical for appropriate management.
Insights
SMARCB1 deficient neoplasms are aggressive tumors with variable morphology. Recognizing these tumors is crucial for effective management, especially with emerging targeted therapies like EZH2 inhibitors.
Area of Science:
- Oncology
- Pathology
Background:
- SMARCB1 deficient neoplasms represent an aggressive and heterogeneous group of tumors with highly variable morphology.
- Recent advancements in targeted therapy, such as EZH2 inhibitors like tazemetostat, have shown potential to improve patient survival.
- Accurate identification of SMARCB1 deficient neoplasms is critical for timely and appropriate clinical management.
Purpose of the Study:
- To characterize the clinicopathological features of SMARCB1 deficient neoplasms.
- To evaluate the diagnostic utility of immunohistochemistry (IHC) for SMARCB1 (INI-1) expression in neoplasm diagnosis.
- To correlate morphological and molecular findings in SMARCB1 deficient neoplasms.
Main Methods:
- A retrospective search of the pathology archive over a 10-year period identified cases with SMARCB1 deficient neoplasm and aberrant SMARCB1 (INI-1) expression.
- Cyto- and histomorphology, immunohistochemistry (IHC), and molecular findings were analyzed.
- 54 cases with complete loss of SMARCB1 (INI-1) and 10 cases with partial loss were included.
Main Results:
- The study identified 54 cases with complete SMARCB1 (INI-1) loss across various sample types (fluids, FNA, biopsies, resections) and age groups (14 days to 87 years).
- Common anatomic sites included head and neck, CNS, lymph nodes, thorax/lung, and liver.
- Morphological findings included poorly differentiated carcinoma, basaloid, rhabdoid, or epithelioid sarcomas, often with positive cytokeratin stains and complex genetic abnormalities.
Conclusions:
- Ancillary testing for SMARCB1 (INI-1) is recommended for tumors exhibiting bizarre cytomorphology, particularly poorly differentiated or pleomorphic tumors.
- Cytological recognition of SMARCB1 deficient neoplasms is essential for guiding appropriate patient management.
- The findings underscore the importance of identifying SMARCB1 deficiency for therapeutic decisions.
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