关键词: 梭形细胞, 硬化, 横纹肌肉瘤, 免疫表型

Abstract: PURPOSE: To study the clinicopathologic features,immunophenotype and prognosis of spindle cell and sclerosing rhabdomyosarcomas（SRMS/ScRMS） in the head and neck region. METHODS: The clinical, pathological and immunohistochemical features were evaluated in 15 cases of SRMS/ScRMS in the head and neck region. RESULTS: Fifteen cases of spindle cell and sclerosing rhabdomyosarcomas（10 SRMS and 5 ScRMS）in the head and neck region were retrieved from the pathological archive, which were diagnosed and reviewed by two independent pathologists,with the classification based on current WHO criteria as SRMS/ScRMS. Seven cases were male and 8 were female. Their ages ranged from 2 months to 57 years (median 20.1 years). The most common anatomic location of the neoplasms was the infratemporal fossa (n=5), followed by the soft tissue of maxilla (n=2),the tongue (n=2), as well as the masseteric region, the soft tissue of mandible, the pterygomandibular space, the parotid region, the neck and the lip. Tumor size varied from 1.5 to 20 cm (median 6.3 cm). Histologically, all SRMS of 10 were mainly composed of cellular bands and fascicles of low-grade atypical spindle-shaped tumor cells with a variable number of spindled or polygonal rhabdomyoblasts. All ScRMSof 5 were characterized by the presence of large amounts of heavily hyalinized matrix, mimicking osteoid or chondroid tissue . The tumor cells were composed predominantly of primitive small round cells which were arranged in diverse growth patterns, including fascicular, trabecular, microalveolar and pseudovascular structures. Immunohistochemically, all the tumor cells of SRMS/ScRMS showed diffuse expression of vimentin and desmin. MyoD1 immunostaining was diffuse to multifocally positive. Twelve cases showed myogenin positive immunostaining, but all cases were negative for S100, HMB-45, Caldesmon, CK and CD34. All the patients underwent surgical resection, and only 3 patients had chemotherapy and radiotherapy after surgery as adjuvant treatment. Completed clinical follow-up information was available from 14 patients, ranging from 4 to 205 months（median 59 months）, of which 5 cases had no-evidence of disease, but 9 cases died of recurrence or distant metastasis after surgery. CONCLUSIONS: SRMS/ScRMS of the head and neck region has a predilection for children and adolescents that may be associated with unfavorable outcomes. Familiarity with its morphological features and immunophenotype may help to distinguish this distinct variant of rhabdomyosarcoma from variety of lesions with abundant sclerosing matrix.

Key words: Spindle cell, Sclerosing, Rhabdomyosarcoma, Immunophenotype