oral medicine & Pathology

Rhabdomyosarcoma : imaging , clinical findings , pathology , treatment , epidemiology

 Rhabdomyosarcoma

 

Epidemiology

  •  Rhabdomyosarcomas are most commonly seen in the pediatric age group. This malignant neoplasm is also the most common soft tissue tumor in childhood.
  • It accounts for about 50 to 70% of all childhood sarcomas.
  • Approximately 30 to 40% occur in the head and neck.
  • About half of patients present before the age of 5 years.
  • There is no sex predilection.

Clinical Findings

  •   Signs and symptoms depend on the size and location of the lesion.
  • Large tumors often cause trismus as a result of masticator muscle dysfunction or involvement of the temporomandibular joint.
  • Pain may be related to bone erosion or nerve involvement.
  • Physical examination reveals medial displacement of the pharyngeal mucosa.
  • Patients may also present with nasal stuffiness if the tumor extends into the maxillary sinus or nasal cavity.
  • These complaints may be similar to those of a juvenile angiofibroma.

Pathology

  •  There are four histologic subtypes. The well-differentiated pleomorphic type is most commonly seen in adults.
  • The alveolar type predominates in the adolescent age group.
  • The embryonal and botryoid types are typically encountered in childhood.
  • Besides the masticator space, other common sites include the orbit, nasopharynx, mastoid and middle ear, and the sino nasal area.
  • The tumor spreads by both lymphatic and hematogenous routes.
  • Metastasis to the lungs, bones, and marrow is common.
  • In 8% of patients regional nodal spread can be seen.

Treatment

  •   Rhabdomyosarcoma is best treated using a multimodality approach including surgery, radiation therapy, and chemotherapy.
  • The best prognosis is seen in orbital rhabdomyosarcomas.
  • Tumors that involve the nasopharynx and sinonasal regions have a propensity to extend intracranially and tend to have the worst prognosis.
  • However, the prognosis has improved over the years with an overall 3-year survival of 85% and a 5-year disease free rate approaching 73%.

Imaging Findings

CT

  •   The tumor is usually large at presentation.
  • Contrast-enhanced CT usually shows mild enhancement.
  • These tumors may extend anteriorly into the maxillary sinus and demonstrate aggressive destruction of the posterior wall of the sinus.
  • Advanced lesions may also demonstrate aggressive bone destruction of the mandible and skull base.

MR

  •  These locally aggressive tumors are an intermediate signal on T l -weighted sequences and ahigh signal on T2W .
  • The tumors homogeneously enhance following intravenous contrast.
  • The internal characteristics tend to be homogeneous without internal flow voids.  

Imaging Pearls

•     A rhabdomyosarcoma should be the initial consideration for a primary rumor arising within the masticator space in a child .

• The lack of flow voids and the presence of aggressive bone desrruction help differentiate a rhabdomyosarcoma from a juvenile angiofibroma in an adolescent male that extends into the sinonasal region.

 

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