Sclerosing Rhabdomyosarcoma in Childhood: Case Report and Review of the Literature

Abstract

Rhabdomyosarcoma is the most common soft tissue malignancy in children but is rare in adults. The latest World Health Organization classification of soft tissue tumors recognizes embryonal, alveolar, and pleomorphic rhabdomyosarcomas. More recently, a sclerosing variant of rhabdomyosarcoma has been recognized and reported in seven adult patients. We describe a pediatric case of sclerosing rhabdomyosarcoma presenting as a sacral mass in a 3-year-old girl. Morphologically, the tumor showed a prominent sclerosing hyaline matrix and demonstrated pseudovascular and microalveolar architectural foci. Focal positivity was seen with desmin, smooth muscle actin, and myogenin. MyoD1 showed uniform diffuse nuclear staining. Fusion transcripts were not demonstrated by reverse transcriptase-polymerase chain reaction analysis. The histology, immunohistochemistry, and molecular genetics matched those reported in the seven adult cases of sclerosing rhabdomyosarcoma. This is the first case report, to our knowledge, of this rare tumor arising in the pediatric age group, and we compare the features with those reported in adult sclerosing rhabdomyosarcoma.

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

“…With regard to immunohistochemical markers supportive of skeletal muscle differentiation, MyoD1 generally has been viewed as a more sensitive marker for SRMS than desmin and myogenin, based upon observations by Folpe et al and subsequent authors [4,6,9,12,17]. Nevertheless, we caution that strong, diffuse reactivity for MyoD1 is not a uniform finding (focal or weak staining: n = 9, negative: n = 1) (Table 1).…”

“…Morphologically, the observation of overt myogenesis with the presence of rhabdomyoblasts in one-third of SRMS cases would favor an association with ERMS. However, alveolar or microalveolar architecture likened to ARMS occasionally has been reported in SRMS as well [4,6,12]. Although prominent extracellular matrix production generally is rare in RMS, some cases of ARMS have thin fibrous bands, which somewhat resemble the hyalinizing matrix in SRMS [2,4].…”

“…Clinicopathologic and molecular genetic characterization of additional cases may help resolve how to classify this lesion in the future. Table 2 Summary of clinicopathologic data for 39 reported cases (including the current case) of sclerosing rhabdomyosarcoma [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Feature …”

“…These authors reported a series of unusual rhabdomyosarcoma cases, exhibiting prominent hyaline sclerosis and a pseudovascular growth pattern. Additional cases have been reported since in both adult and pediatric patients, with a marked predilection for the extremities and head and neck region [4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Here we report a new case of SRMS, centered within the pterygomaxillary fossa of an adult male.…”

“…The lesions typically were infiltrative, although one case exhibited well-demarcated borders [14]. A pseudovascular growth pattern was noted in 11 cases [3,6,9,10,12,17]. Fascicular, nested, cordlike, trabecular, solid, and rarely alveolar architectural patterns also were observed.…”