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A 13-year-old male presented to the pediatric otolaryngology clinic with a 2-year history of a right neck mass that had slowly increased in size. He denied any associated symptoms of pain, fevers, chills, malaise, night sweats, unintentional weight loss, prior history of neck masses, recent upper respiratory tract infections, or skin lesions. He was the product of a full-term pregnancy with up-to-date immunizations. Physical examination revealed a 2.5-cm firm, ovoid, mobile, and nontender mass at the apex of the posterior triangle of the right neck without any associated overlying skin changes. The remainder of the head and neck examination was unremarkable. Doppler ultrasonography revealed a 1.9 × 1.8 × 0.9-cm hypoechoic mass, and subsequent fine-needle aspirates demonstrated cells with elongated nuclei and eccentric blue cytoplasm in a background of myxoid stroma. The mass was excised in entirety without issue. At the time of surgery, the deep surface of the mass was found to be adherent to the sternocleidomastoid muscle. The lesion was resected with a cuff of muscle and sent for permanent histopathological examination. This revealed proliferation of bland spindle cells with plump nuclei and eosinophilic cytoplasm arranged as loose fascicles in a background of myxoid stroma (Figure 1). These cells were positive for mucin 4 (MUC4), epithelial membrane antigen (EMA), and transducing-like enhancer of split 1 (TLE1) immunohistochemical stains. Fluorescence in situ hybridization (FISH) revealed a positive FUS (16p11) gene rearrangement.
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C. Low-grade fibromyxoid sarcoma
Primary sarcomas of the head and neck are unusual, with a prevalence of 1% to 2%.1,2 Of these, low-grade fibromyxoid sarcomas (LGFMS) of the head and neck are exceedingly rare with only 26 cases described in literature.2 Low-grade fibromyxoid sarcomas often present in superficial subcutaneous tissue in children rather than the deep tissues of the proximal extremities commonly seen in young adults.3 Although multiple case series have described the indolent nature of LGFMS, there is a predilection for late recurrence after 15 years (median, 3.5 years) and pulmonary metastasis at a median of 5 years. Low-grade fibromyxoid sarcomas have a protracted clinic course with disease-specific survival of up to 70 years.4
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Corresponding Author: Saikrishna C. Gourishetti, MD, Department of Otorhinolaryngology–Head and Neck Surgery, University of Maryland School of Medicine, 16 S Eutaw St, Ste 500, Baltimore, MD 21201 (firstname.lastname@example.org).
Published Online: September 9, 2021. doi:10.1001/jamaoto.2021.2314
Conflict of Interest Disclosures: No disclosures.
Additional Contributions: We thank the patient’s guardian for granting permission to publish this information.
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