Rhabdomyosarcoma, embryonal

Rhabdomyosarcoma, Embryonal

Rhabdomyosarcoma (RMS) is a malignant tumor of mesenchymal origin, specifically arising from skeletal muscle progenitors. The embryonal subtype is the most common form of rhabdomyosarcoma, typically affecting children.

Overview

Embryonal rhabdomyosarcoma (ERMS) is a soft tissue sarcoma that primarily occurs in children, with the majority of cases diagnosed in patients under the age of 10. It is characterized by its resemblance to the developing embryonic skeletal muscle.

Pathophysiology

ERMS arises from primitive mesenchymal cells that are committed to skeletal muscle lineage. These tumors often exhibit a loss of heterozygosity at chromosome 11p15.5, which is associated with the deregulation of the IGF2 gene, contributing to tumorigenesis.

Clinical Presentation

Patients with ERMS may present with a mass or swelling in various anatomical locations, including the head and neck region, genitourinary tract, and extremities. Symptoms depend on the tumor's location and may include:

• Nasal obstruction or discharge if located in the nasopharynx.
• Hematuria or urinary obstruction if located in the bladder or prostate.
• Vaginal bleeding or discharge in cases of vaginal tumors.

Diagnosis

The diagnosis of ERMS involves a combination of imaging studies, biopsy, and histopathological examination. Imaging modalities such as MRI and CT scans are used to assess the extent of the disease. Histologically, ERMS is characterized by small, round, blue cells with varying degrees of differentiation towards skeletal muscle.

Treatment

The treatment of ERMS typically involves a multimodal approach, including:

• Surgery: Complete surgical resection is the goal when feasible.
• Chemotherapy: Agents such as vincristine, actinomycin D, and cyclophosphamide are commonly used.
• Radiation therapy: Employed in cases where surgical margins are positive or inoperable tumors.

Prognosis

The prognosis for patients with ERMS depends on several factors, including the tumor's size, location, and the presence of metastases. The Intergroup Rhabdomyosarcoma Study (IRS) group classification is often used to stratify patients and guide treatment.

Also see

• Rhabdomyosarcoma
• Alveolar rhabdomyosarcoma
• Soft tissue sarcoma
• Pediatric oncology