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Published on: May 23, 2015
A Rare Case of CIC-DUX4 Sarcoma in a Mediastinal Lymph Node Diagnosed by Fine Needle Aspiration Cytology
Fnu Mahjabin1, Tara J Hajarat1, Alexandra De Leo2
1Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA.
Abstract:
CIC-rearranged sarcomas (CDS) are rare, aggressive undifferentiated small round cell tumors recently classified as a distinct entity by the World Health Organization. These tumors are defined by CIC gene fusions, most commonly CIC::DUX4, and are associated with poor prognoses and diagnostic challenges, particularly in limited cytological samples. We report the case of a 37-year-old male who presented with respiratory symptoms and was found to have mediastinal lymphadenopathy. Fine-needle aspiration (FNA) of a right paratracheal lymph node revealed hypercellular smears of dyscohesive tumor cells with high nuclear-to-cytoplasmic ratios, prominent nucleoli, and cytoplasmic vacuoles. Immunohistochemistry showed positivity for WT1, CD99, and vimentin, while RNA sequencing confirmed a CIC::DUX4 fusion, establishing the diagnosis of CDS. This case highlights the critical role of integrating cytopathology, immunohistochemistry, and molecular diagnostics in identifying CDS, particularly in atypical anatomical sites. Early and accurate diagnosis is essential for guiding clinical management in this rare and aggressive sarcoma subtype.
Insights
CIC-rearranged sarcomas (CDS) are rare, aggressive tumors. This case report details diagnosing CDS using cytopathology, immunohistochemistry, and molecular testing in a patient with mediastinal lymphadenopathy.
Area of Science:
- Oncology
- Pathology
- Genetics
Background:
- CIC-rearranged sarcomas (CDS) are a recently classified, rare, and aggressive group of undifferentiated small round cell tumors.
- These tumors are characterized by CIC gene fusions, primarily CIC::DUX4, and present diagnostic challenges, especially in small samples.
- CDS are associated with poor prognoses and require accurate identification for effective management.
Purpose of the Study:
- To report a case of CIC-rearranged sarcoma diagnosed in mediastinal lymphadenopathy.
- To emphasize the importance of integrating diagnostic modalities for CDS.
- To highlight the diagnostic utility of cytopathology, immunohistochemistry, and molecular analysis in rare sarcoma subtypes.
Main Methods:
- Case presentation of a 37-year-old male with respiratory symptoms and mediastinal lymphadenopathy.
- Fine-needle aspiration (FNA) cytology analysis of a paratracheal lymph node.
- Immunohistochemistry (IHC) for WT1, CD99, and vimentin.
- RNA sequencing to detect CIC gene fusions.
Main Results:
- FNA smears showed hypercellularity with dyscohesive tumor cells exhibiting high nuclear-to-cytoplasmic ratios, prominent nucleoli, and vacuoles.
- Immunohistochemistry was positive for WT1, CD99, and vimentin.
- RNA sequencing confirmed the presence of a CIC::DUX4 fusion, establishing the diagnosis of CDS.
Conclusions:
- The integration of cytopathology, immunohistochemistry, and molecular diagnostics is crucial for diagnosing CIC-rearranged sarcomas.
- Accurate and early diagnosis of CDS, even in unusual locations like mediastinal lymph nodes, is vital for patient management.
- This case underscores the diagnostic approach for this rare and aggressive sarcoma.
