Related Experiment Video
Updated: Nov 16, 2025
Author Spotlight: Genetically Engineered Mouse Models and Pathological Characterization of Neurofibromatosis Type 1 Associated Tumors
Published on: May 17, 2024
Cytomorphologic Spectrum of SMARCB1-Deficient Soft Tissue Neoplasms
Inga-Marie Schaefer1, Alyaa Al-Ibraheemi2, Xiaohua Qian1
1Department of Pathology, Brigham and Women's Hospital.
Objectives:
The SWI/SNF complex core subunit SMARCB1 is inactivated in a variety of neoplasms that share characteristic "rhabdoid" cytomorphology. The aim of this study was to evaluate SMARCB1-deficient soft tissue neoplasms on cytology to identify diagnostic clues.
Methods:
Eleven SMARCB1-deficient tumors, including six epithelioid sarcomas, three malignant rhabdoid tumors, one epithelioid malignant peripheral nerve sheath tumor (MPNST), and one poorly differentiated chordoma with fine-needle aspiration (FNA), serous effusion, or touch prep (TP) from two institutions, were included. Targeted next-generation sequencing (NGS) was performed in two cases.
Results:
Evaluation of FNA (n = 4), effusion (n = 4), and TP (n = 3) in nine adult and two pediatric patients demonstrated cellular samples (n = 11), epithelioid cells with rhabdoid morphology (n = 9), eccentrically located nuclei with prominent nucleoli (n = 7), and cytoplasmic bodies (n = 4); two patients were diagnosed on FNA with cell block. Immunohistochemistry (IHC) demonstrated SMARCB1 loss in all cases and keratin and/or EMA expression in all but the epithelioid MPNST; NGS identified SMARCB1 inactivation in both cases.
Conclusions:
SMARCB1-deficient soft tissue neoplasms comprise a variety of tumors with epithelioid morphology and frequent expression of keratin and/or EMA. Recognition of characteristic rhabdoid morphology on cytology can prompt IHC and/or NGS testing for SMARCB1 deficiency and help establish the diagnosis.
