Pediatric sclerosing rhabdomyosarcomas: a review

Abstract

Sclerosing RMS (SRMS) is a recently described subtype of RMS that has not yet been included in any of the classification systems for RMSs. We did pubmed search using keywords "sclerosing, and rhabdomyosarcomas" and included all pediatric cases (age ≤ 18 years) of SRMSs in this review. We also included our case of an eleven-year-old male child with skull base SRMS and discuss the clinical, histopathological, immunohistochemical, and genetic characteristics of these patients. Till now, only 20 pediatric cases of SRMSs have been described in the literature. Pediatric SRMS more commonly affects males at a mean age of 9 years. Extremeties and head/neck regions were most commonly affected. Follow-up details were available for 16 patients with mean follow-up of 25.3 months. Treatment failure rate was 43.75%. Overall amongst these 16 patients, 10 were alive without disease, 4 were alive with disease, and two died. Thus, overall and disease-free survival amongst these 16 patients were 87.5% and 62.5%, respectively. The literature regarding clinical behaviour and outcome of pediatric patients with SRMSs is patchy. Detailed molecular/genetic analysis and clinicopathological characterization with longer follow-ups of more cases may throw some light on this possibly new subtype of RMS.

Figure 1

Preoperative images showing a large middle cranial fossa lesion with extension into the infratemporal region (e and f) that is isodense on CT scan (a), hypointense on T1 weighted images (b), hyperintense on T2 weighted images (c), and enhanced homogenously on contrast administration (d, e, and f).

Figure 2

Photomicrographs showing small round cells arranged in Indian file pattern (a), at places showing microalveolar (b) and spindling pattern (c) with hyaline myxoid stroma in the background (H & E ×400). Mitoses are present. The stroma is stained blue with Masson Trichrome stain (d, ×400).

Figure 3

Tumor cells are immunopositive for (a) desmin and (b) focal for myogenin (×400 each). MIB I LI is high (c, ×400).

Figure 4

Postoperative images at 1-year follow up showing evidence of previous craniotomy (a). Leptomeningeal metastases are seen both in the intracranial (b, d, and e) and intraspinal (c and f) compartments. The cervical spinal cord is severely compressed by intradural extramedullary metastases (c and f).