Clinicopathological features of five cases of CIC::DUX4 positive sarcomas, including literature review

CIC-rearranged sarcoma in the breast: A series of 3 rare cases with literature review

Capticua transcriptional repressor (CIC)-rearranged sarcoma represents a distinct highly aggressive, undifferentiated round cell sarcomas, which most commonly affects young adults. The tumor typically arises in the deep soft tissues of the limbs and trunk, followed by the head and neck region, and is rarely found in visceral organs. CIC-rearranged sarcoma originating in the breast is extremely rare with only one case having been reported in the literature. We report three cases of CIC-rearranged sarcoma in the breast, all occurring in young females and exhibiting aggressive clinical behavior. Microscopically, all three cases showed diffuse or lobular growth of small round blue tumor cells with vesicular nuclei, prominent nucleoli, and clear cytoplasm. Focal reticular growth pattern and myxoid stroma were also observed. The diagnosis of CIC-rearranged sarcoma was confirmed through either fluorescence in situ hybridization (FISH) or RNA sequencing; two of the three cases were confirmed to harbor CIC::DUX4 fusion. This case series, to the best of our knowledge, represents the largest report of CIC-rearranged sarcoma in the breast. It highlights the importance of recognizing this rare entity in the breast due to its aggressive clinical course, poor response to chemotherapy, and high tendency for metastasis. It also emphasizes the utility of molecular studies in distinguishing CIC-rearranged sarcoma from poorly differentiated carcinoma, as CIC-rearranged sarcoma has significantly worse prognosis than poorly differentiated carcinoma of breast.

Mesenchymal Nonmeningothelial Tumors of the CNS: Evolving Molecular Landscape and Implications for Neuroradiologists

The World Health Organization Classification of Tumors of the Central Nervous System, 5th edition (WHO CNS5) significantly revised the terminology and diagnostic criteria of "mesenchymal nonmeningothelial" tumors of CNS to better align with the classification of these soft tissue tumors outside the CNS. The CNS chapter only covers the entities with distinct histologic or molecular characteristics that occur exclusively or primarily in the CNS. These tumors usually arise from the meninges and are rarely intraparenchymal in origin, mainly in the supratentorial compartment. These tumors are grouped into 3 main categories: soft tissue, chondro-osseous, and notochordal. Soft tissue tumors, the largest group, are further divided into fibroblastic, vascular, and skeletal muscle subtypes. Notably, a new subcategory for "tumors of uncertain differentiation" has been introduced, encompassing 3 new histomolecular entities: FET::cAMP response element-binding protein (CREB) fusion-positive, Capicua transcriptional receptor (CIC)-rearranged sarcoma, and primary intracranial sarcoma, DICER1-mutant. Emerging entities like dural angioleiomyomas and spindle cell neoplasms with neurotrophic receptor kinase (NTRK) rearrangements have been reviewed, although not introduced in WHO CNS5. Given the often nonspecific histology and immunophenotype of mesenchymal nonmeningothelial tumors of uncertain differentiation, molecular techniques have become indispensable for accurate diagnosis. This review provides a comprehensive overview of primary mesenchymal nonmeningothelial CNS tumors, including their clinical, radiologic, histopathologic, and molecular characteristics and treatment strategies.

Cerebral CIC-NUTM1 rearrangement sarcoma- case report and review of the literature

Background

Ewing sarcoma and Ewing-like sarcoma are both highly aggressive small round cell sarcomas, while CIC rearranged sarcoma (CRS), the most common specific type of Ewing-like sarcoma, exhibits a more aggressive course than Ewing sarcoma and represents a distinct family of sarcomas. NUT midline carcinoma family member 1 (NUTM1) is a characteristic fusion gene of NUT midline carcinoma. In this paper, the intracranial tumor CIC is mainly fused with NUTM1, which is considered to be a molecular variant of CIC sarcoma.

Case presentation

We report a 9 years old female patient diagnosed with CIC rearrangement sarcoma with CIC-NUTM1 gene rearrangement and PMS2 frameshift mutation, WHO grade 4. We treated the patient with surgical resection. Due to the poor postoperative condition of the patient, coupled with the inherently poor prognosis of CIC-NUTM1 sarcoma, the patient ultimately had a short survival time and the treatment outcome was not satisfactory.

Conclusion

We experienced a rare case of an intracranial tumor with CIC-NUTM1 fusion and a PMS2 frameshift mutation. Due to the small sample size, rapid progression, and poor prognosis associated with this type of tumor, it is essential to enhance understanding and diagnosis of this type of sarcoma.

Ancillary Tools for the Diagnosis of CIC -Rearranged Sarcoma: A Comprehensive Review

CIC-rearranged sarcoma is a rare and aggressive undifferentiated round cell sarcoma that presents significant diagnostic challenges due to its histologic overlap with other round cell sarcomas. This review, conducted on behalf of the American Society of Dermatopathology Appropriate Use Criteria Committee (soft tissue subgroup), provides an overview of current immunohistochemical, cytogenetic, and molecular tests used to support the diagnosis of CIC-rearranged sarcoma. This comprehensive analysis included 36 studies, encompassing 436 CIC-rearranged sarcomas. The immunohistochemical markers, CD99 (typically non-diffuse), nuclear WT1, ETV4, and DUX4, were found to be relatively highly sensitive for CIC-rearranged sarcoma (CD99: 87%, WT1: 83%, ETV4: 85%, DUX4: 97%). However, the specificity of these markers is variable, with CD99 being highly non-specific, while WT1 (81%-90%), ETV4 (95%), and DUX4 (100%) offering greater specificity. CIC break-apart FISH can be a helpful and cost-effective assay for detection of CIC-rearrangements, but has a false-negative rate that ranges from 26% to 43%. Next-generation sequence RNA fusion analysis also carries a risk of false negatives, which may be partly mitigated through manual data review. Ultimately, an accurate diagnosis of CIC-rearranged sarcoma requires careful morphologic assessment in combination with immunohistochemical studies and cytogenetics/molecular assays.

CIC-DUX4 Sarcoma of the Skin: A Rare Case Report and Literature Review

CIC::DUX4 fusion sarcoma represents a rare and aggressive subtype of undifferentiated small round blue cell tumors. We report on a 23-year-old African male who developed a rapidly enlarging inferolateral left buttock nodule with ulceration. After debulking excision of the lesion, histologic sections demonstrated sheets and lobules of atypical round blue cells with significant cytologic atypia. Prominent foci of atypical mitotic figures and tissue necrosis were present. Tumoral cells stained strongly and diffusely using MDM2, vimentin, WT1 and CD99 immunohistochemical (IHC) markers. Molecular testing was performed and highlighted CIC::DUX4 gene fusion positivity, making the diagnosis of a CIC::DUX4 sarcoma (CDS). Post-surgical excision, the patient showed no disease on imaging and underwent five cycles of adjuvant chemotherapy with no recurrence observed at the eight-month follow-up. With fewer than 200 cases reported in the literature and somewhat nonspecific clinicopathologic characteristics, CIC::DUX4 sarcoma presents a diagnostic challenge. This case underlines the importance of molecular diagnostics in undifferentiated sarcomas and presents a rare primary cutaneous manifestation of CIC::DUX4 fusion sarcoma. Additionally, we provide a review of the literature to aid in recognition, diagnosis, and treatment of this rare entity.

Clinical outcomes of patients with CIC-rearranged sarcoma: a single institution retrospective analysis

PURPOSE

CIC-rearranged sarcomas represent a type of undifferentiated small round cell sarcoma (USRCS) characterized by poor survival, rapid development of chemotherapy resistance, and high rates of metastasis. We aim to contribute to the growing body of knowledge regarding diagnosis, treatment, clinical course, and outcomes for these patients.

METHODS

This case series investigates the clinical courses of ten patients with CIC-rearranged sarcoma treated at the Johns Hopkins Hospital from July 2014 through January 2024. Clinical data were retrospectively extracted from electronic medical records.

RESULTS

Patients ranged from 10 to 67 years of age at diagnosis, with seven patients presenting with localized disease and three with metastatic disease. Tumors originated from soft tissues of various anatomic locations. Mean overall survival (OS) was 22.1 months (10.6-52.2), and mean progression-free survival (PFS) was 16.7 months (5.3-52.2). Seven patients received intensive systemic therapy with an Ewing sarcoma-directed regimen or a soft tissue sarcoma-directed regimen. Three patients experienced prolonged disease-free survival without systemic treatment.

CONCLUSION

Most patients in this case series demonstrated aggressive clinical courses consistent with those previously described in the literature, although we note a spectrum of clinical outcomes not previously reported. The diversity of clinical courses underscores the need for an improved understanding of individual tumor biology to enhance clinical decision-making and patient prognosis. Despite its limitations, this article broadens the spectrum of reported clinical outcomes, providing a valuable addition to the published literature on this rare cancer.