Sclerosing Rhabdomyosarcoma: Report of a Case Arising in the Head and Neck of an Adult and Review of the Literature

Abstract

Sclerosing rhabdomyosarcoma is a unique rhabdomyosarcoma variant, characterized by a prominent hyalinizing matrix. A notable pitfall is the potential for the unusual matrix and often pseudovascular growth pattern of this lesion to lead to confusion with other sarcoma types, including osteosarcoma, chondrosarcoma, and angiosarcoma. Here we report a case of sclerosing rhabdomyosarcoma arising in a 40-year old male. The tumor was centered in the pterygomaxillary fossa with extensive infiltration into adjacent structures. Fine needle aspiration yielded a preliminary diagnosis of high-grade pleomorphic undifferentiated sarcoma, for which he received neoadjuvant chemotherapy and surgical resection. Microscopic examination showed a malignant spindled to round cell neoplasm with prominent osteoid-like, hyaline stroma. Focal rhabdomyoblastic differentiation and diffuse immunoreactivity for desmin and myogenin aided in diagnosis. Nineteen months status post primary resection, the patient expired with multiple lung and bony metastases. Among 39 cases reported thus far (including the present case), there is a broad age range (0.3-79 years), with an average age at presentation of 27 years. The most commonly involved sites are the extremities (n = 19) and head and neck (n = 15). Most cases have been treated by resection, often combined with radiation and/or chemotherapy. Out of 31 cases with follow-up information provided, 6 patients developed local recurrence, 7 patients developed regional or distant metastasis, and 5 patients died of disease. Herein we discuss the ongoing controversy regarding how sclerosing rhabdomyosarcoma might best fit into existing rhabdomyosarcoma classification schemes, based upon current clinicopathologic and molecular genetic evidence.

Clinicopathologic analysis of spindle cell/sclerosing rhabdomyosarcoma

“…Consensus has not been reached as to the optimal type of treatment of ssRMS . In 6 IRS group I patients, local recurrence took place in only two patients.…”

“…According to our results, ssRMSs tend to be diagnosed at an advanced stage because of the primary site (parameningeal or extremities) and because of the big size of a tumor at initial diagnosis; however, the finding that distant or lymph node metastases were extremely rare is noteworthy. Consensus has not been reached as to the optimal type of treatment of ssRMS [15]. In 6 IRS group I patients, local recurrence took place in only two patients.…”

Sclerosing Rhabdomyosarcoma: Presentation of a Rare Sarcoma Mimicking Myoepithelial Carcinoma of the Parotid Gland and Review of the Literature

“…Figure 4a, b summarize key epidemiologic features of this rare variant [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The most common sites of presentation of SRMS are the extremities and the head and neck (Fig.…”

“…Currently, the new 4th edition of the WHO classification of Tumors of Soft Tissue and Bone created a provisional category combining SRMS with spindle cell rhabdomyosarcoma (which was also previously included under embryonal rhabdomyosarcoma) [22]. The basis for this recategorization appears to be mainly a result of morphologic overlap between these variants [2,8,13,15,17,23]. Since follow up data for SRMS are limited, and provisional categorization has only recently been established, we can only speculate on the prognostic significance of this entity.…”

“…As the original name would indicate, the tumor cells often line spaces within the stroma imparting vascular appearance [2]. Although occasional cases of SRMS will demonstrate histologic evidence of overt skeletal muscle differentiation with rhabdomyoblasts and strap cells, most cases require confirmation with immunohistochemical studies using markers of skeletal muscle differentiation (e.g., desmin, myogenin, and MyoD1 proteins) [15].…”