Abstract
Background CIC-DUX4 sarcoma is a rare, aggressive tumor that is difficult to diagnose. Although
it is closely related to Ewing's sarcoma, each is a distinct pathologic entity and
both have been previously reported in the skin, lymph nodes, and viscera. We report
the first description of CIC-DUX4 involving the posterior cranial fossa and review
the distinctive symptomatology, morphology, immunoprofile, and genetic signature that
differentiate this rare tumor.
Case Report A 32-year-old man presented with an enlarging right lateral neck mass, progressive
hoarseness, and orofacial pain. Biopsy revealed a high-grade undifferentiated malignant
neoplasm. Imaging demonstrated an 8-cm mass in the right neck extending to the skull
base and abutting the carotid sheath, in addition to pulmonary nodules and pelvic
lymphadenopathy. Despite initial response to chemotherapy, he experienced disease
progression and underwent surgical resection, radical neck dissection, and brachytherapy.
Definitive pathologic diagnosis was achieved with next-generation sequencing. Within
weeks of treatment, he developed symptoms reflecting progression of disease involving
the neck, posterior cranial fossa, and lung. Adjuvant chemotherapy was planned, but
the patient succumbed to his disease prior to initiation of further therapy.
Conclusion CIC-DUX4 sarcomas are uncommon and can progress rapidly. Diagnosis requires either
fluorescence in situ hybridization or next-generation sequencing. Due to its rarity,
there is no standard-of-care treatment for this tumor and further investigations are
needed to understand disease behavior and develop targeted therapeutic modalities.
Keywords
CIC DUX4 sarcoma - Ewing-like sarcoma - round cell sarcoma
