Solid alveolar rhabdomyosarcoma of the thorax in a child

Histopathology. 1998 Feb;32(2):165-71. doi: 10.1046/j.1365-2559.1998.00351.x.


Aims: This case illustrates the difficulties and pitfalls of diagnosis of alveolar rhabdomyosarcoma in its solid variant and in an unusual primary location, the mediastinum.

Case details: A 9-year-old boy presented with a primary thoracic tumour associated with metastasis in the left sacroiliac joint. Bronchial and mediastinal biopsies showed a malignant neoplasm with a solid sheet-like pattern of small round cells with a high nuclear to cytoplasmic ratio associated with little or no fibrosis usually evocative of a peripheral neuroectodermal tumour (PNET) at this age. Immunohistochemical positive staining with vimentin (80% of tumour cells), desmin (20%) and titin (30%) antibodies was suggestive of a rhabdomyosarcoma. In addition, all neural cell adhesion molecule (NCAM) markers tested were positive as well as MIC2, a marker for the Ewing family of sarcomas. There was no rhabdomyoid differentiation at ultrastructural examination. Molecular analysis with RT-PCR amplification of RNA isolated from the tumour demonstrated the presence of a PAX3/FKHR fusion transcript, product of a t(2;13) reciprocal translocation, a genetic marker specific for alveolar rhabdomyosarcoma.

Conclusions: The diagnostic methodology of a small round cell tumour of the child must now include immunohistochemical study and molecular biology to confirm the diagnosis of alveolar rhabdomyosarcoma, in a solid and undifferentiated variant.

Publication types

  • Case Reports

MeSH terms

  • Bronchial Neoplasms / genetics
  • Bronchial Neoplasms / immunology
  • Bronchial Neoplasms / pathology*
  • Child
  • Genetic Markers
  • Humans
  • Immunohistochemistry
  • Immunophenotyping
  • Male
  • Mediastinal Neoplasms / genetics
  • Mediastinal Neoplasms / immunology
  • Mediastinal Neoplasms / pathology*
  • Polymerase Chain Reaction
  • Rhabdomyosarcoma, Alveolar / genetics
  • Rhabdomyosarcoma, Alveolar / immunology
  • Rhabdomyosarcoma, Alveolar / pathology*


  • Genetic Markers