Low-Grade Fibromyxoid Sarcoma of the Head and Neck: A Clinicopathologic Series and Review of the Literature

Abstract

Low-grade fibromyxoid sarcoma (LGFMS) is a deceptively bland malignancy with potential for late recurrence and metastasis, which usually occurs in the deep soft tissues of the extremities and trunk. Most LGFMSs harbor a characteristic gene fusion of FUS-CREB3L2, and recently MUC4 immunostaining has been found to be highly sensitive and specific for the diagnosis. We present a dedicated series of head and neck LGFMS, including the first reported laryngeal case, as well as a review of reported head and neck cases. The surgical pathology archives of our three institutions were searched for cases of LGFMS arising within the head and neck, and four cases were identified. The H&E slides were reviewed, and immunohistochemistry were performed for pancytokeratin, p63, p40, EMA, S100 protein, β-catenin, actin, CD34, and MUC4. The patients were 6, 43, 45, and 73 years old (mean 41.8 years) and included three males and one female. The tumors were located in the posterior cervical spine, facial skin, mandible, and larynx. The tumors were treated with surgical excision, and all four had histologic features typical for LGFMS including alternating myxoid and fibrous areas with prominent curvilinear vasculature. All tumors were MUC4 positive (100%), 2/4 (50%) were p63 positive, 1/4 (25%) showed focal EMA positivity; all 4 were negative for pancytokeratin, p40, S100 protein, β-catenin, actin, and CD34. LGFMS is a low grade sarcoma that rarely develops in the head and neck. Due to its rarity, a pathologist may not consider LGFMS in the differential diagnosis of spindle cell neoplasms within the head and neck. Immunohistochemical staining is helpful, but stains should be selected carefully to avoid misdiagnosis.

Fibromyxoma of the Jaw: Case Report and Review of the Literature

“…Although it is classified as malignant, this lesion has minimal nuclear atypia and rare mitoses. Prominent arching vasculature and collagen rosettes are also seen in these tumors [41].…”

“…In addition, immunohistochemistry for MUC4 may be helpful in establishing the diagnosis. MUC4 shows strong cytoplasmic staining and was positive in all head and neck tumors examined in one study [41]. Therefore, gene rearrangement studies and immunohistochemistry are warranted when LGFMS is suspected.…”

“…LGFMS has both myxoid and fibrous components. LGFMS typically occurs in the proximal extremities, but also is reported in the craniofacial complex [41]. Although it is classified as malignant, this lesion has minimal nuclear atypia and rare mitoses.…”

“…LGFMS may be difficult to distinguish from other bland fibrous and myxoid neoplasms, so adjunctive tests are needed when it is suspected. LGFMS typically displays the FUS/CREB3L2 gene fusion [t(7;16)(q34;p11)] [41]. In addition, immunohistochemistry for MUC4 may be helpful in establishing the diagnosis.…”

Cellular myxoma of the vocal cord: a case report and review of the literature

“…It may show areas of hyalinizing spindle cells with giant rosettes. MUC4 immunostaining has been found to be highly sensitive and specific for the diagnosis (17). Myxoid liposarcoma has small, bland spindle-shaped or more rounded cells, lipoblasts and a typically delicate plexiform or branching "chicken-wire" capillary vasculature (18).…”