rhabdomyosarcoma

Teenager with
left chest wall massCXR PA and lateral (above) shows an ill defined left-sided pleural-based process. Axial CT without contrast of the chest (below) shows a mass arising from the muscles of the left chest wall which invades up into the pleural space and down into the abdomen, sparing the ribs.The diagnosis was rhabdomyosarcoma.
pediatricimaging.org • CC-by-nc-sa 4.0
Toddler with
recently noted urinary retention. AP image from the excretory phase of a vintage intravenous pyelogram (above) shows bilaterally normal appearing renal collecting systems and ureters. There is a multilobulated circumferential filling defect in the base of the badder. Axial CT with contrast of the abdomen shows the mass to almost complete fill the base of the bladder.The diagnosis was rhabdomyosarcoma of the bladder.
pediatricimaging.org • CC-by-nc-sa 4.0
Male
preschooler with urinary retention. Axial CT with contrast of the abdomen shows a soft tissue mass arising from between the bladder and rectum that is invading into the posterior wall of the bladder, resulting in filling defects within the bladder.The diagnosis was genitourinary rhabdomyosarcoma arising from the prostate and invading the bladder.
pediatricimaging.org • CC-by-nc-sa 4.0
Imaging of
parotid anomalies in infants and children. Embryonic rhabdomyosarcoma. Heterogeneous structure and vascularization on B-mode sonography and color Doppler (a and b), large at the time of diagnosis on frontal T2-weighted image (c)
insightsimaging.springeropen.com • CC-by-4.0
MRI imaging
of soft tissue tumours of the foot and ankle. Rhabdomyosarcoma. Short axis T1 image (a) of the foot of a 14-year-old girl demonstrating a hyperintense mass in the first web-space with avid enhancement on postcontrast T1FS imaging (b)
insightsimaging.springeropen.com • CC-by-4.0
Preschooler
with 2 weeks of right eye swelling. Axial T1 MRI without (above left) and with contrast (above right) of the orbits show a solid homogenously enhancing mass arising superior and medially to the right orbit which shows restricted diffusion on diffusion weighted imaging (below right).The diagnosis was rhabdomyosarcoma.
pediatricimaging.org • CC-by-nc-sa 4.0
Radiopaedia • CC-by-nc-sa 3.0 • de

Rhabdomyosarcoma (RMS) is a malignant tumor with skeletal muscle cell morphology. It is one of the tumors of muscular origin.

This article focuses on a general discussion of rhabdomyosarcomas. For location specific details, please refer to:

Epidemiology

Rhabdomyosarcomas are the most common soft tissue tumor in children and account for 5-8% of childhood cancers, and 19% of all pediatric soft tissue sarcomas .

In general, they are found in young patients, less than 45 years of age , with ~65% diagnosed in patients under 10 years old .

There is a slight male predilection (M:F 1.67:1 ) with Caucasian children affected more often than children of other races.

Clinical presentation

Clearly, clinical presentation will vary depending on the location of a tumor (see below); however, in general, rhabdomyosarcomas are rapidly growing masses. They cause localized pressure effects on neurovascular structures and have a predilection for infiltrating bones . Pathological fractures could therefore occur.

These tumors can occur anywhere, and not necessarily where the skeletal muscle is normally found. In children and adolescents, they occur predominantly in the head, neck and pelvis.

Distribution 

Rhabdomyosarcomas are found essentially anywhere in the body :

  • head and neck: ~50% *
    • orbit: ~20%
    • oropharynx/nasopharynx, palate: ~15%
    • sinuses, mastoid, middle ear: ~15%
  • genito-urinary: ~25%
    • paratesticular: ~20%
    • bladder: ~5%
  • extremities: ~15%
  • other: ~10%
    • trunk and thorax: 7%
    • gastrointestinal tract: 1%

*: see note on figures/percentages

Pathology

Rhabdomyosarcomas are thought not to arise from skeletal muscle, but rather to differentiate into a tumor which resembles skeletal muscle . This accounts for it arising in locations where no skeletal muscle is present. It is divided into three subtypes :

  • embryonal rhabdomyosarcoma
  • alveolar rhabdomyosarcoma: 20%
  • pleomorphic rhabdomyosarcoma: 5%
    • Associations

    Although the vast majority of cases are sporadic, increased incidence of rhabdomyosarcomas is seen in patients with a variety of syndromes and congenital anomalies, including :

    Staging

    Please refer to Rhabdomyosarcoma staging.

    Radiographic features

    Unfortunately, the appearance of the mass itself is non-specific and indistinguishable from other sarcomas. The location and demographics of the patient are most useful in narrowing the differential.

    Plain radiograph

    Although entirely non-specific plain films are a useful first step as they can give a quick global view of the region and identify calcifications in the mass, bony involvement and metastases. The mass appears of soft tissue density.

    When present in the extremities in children, embryonal rhabdomyosarcomas may cause bowing of the adjacent long bones. This should not be thought of as suggesting slow growth or indolent behavior .

    Ultrasound
    • heterogeneous well-defined irregular mass of low to medium echogenicity
    CT
    • soft tissue density
    • some enhancement with contrast
    • adjacent bone destruction is seen in over 20% of cases
    MRI

    Signal characteristics include:

    • T1
      • low to intermediate intensity, isointense to adjacent muscle
      • areas of hemorrhage are common in alveolar and pleomorphic subtypes
    • T2
      • hyperintense
      • prominent flow voids may be seen particularly in extremity lesions
    • T1 C+ (Gd): shows considerable enhancement

    Embryonal rhabdomyosarcomas tend to be more homogeneous, whereas alveolar and pleomorphic rhabdomyosarcomas frequently have areas of necrosis . The latter is associated with ring-like enhancement .

    Treatment and prognosis

    Unfortunately, up to 20% of patients have metastases at the time of diagnosis . These are typical to lung and bone marrow.

    Treated with combination surgery, chemotherapy, and radiation:

    • surgery: resection of a primary tumor, if necessary after down-staging chemoradiotherapy
    • chemotherapy: common agents include vincristine, cyclophosphamide, dactinomycin, adriamycin, ifosfamide, VP-16
    • radiotherapy: external beam radiation is used in some cases of rhabdomyosarcoma 

    Survival varies dependent on primary location, histological type, local invasion and metastases. Overall 5-year survival is approximately 75% .

    Siehe auch:
    und weiter:
    Assoziationen und Differentialdiagnosen zu Rhabdomyosarkom:
    Neurofibromatose
    Typ 1
    Wikipedia • CC BY-SA 3.0
    Rhabdomyosarkom
    der Kopf-Hals-Region
    insightsimaging.springeropen.com • CC-by-4.0
    Rhabdomyosarkom
    der Blase
    pediatricimaging.org • CC-by-nc-sa 4.0