Background

1-year-old male, presented with soft tissue mass in left pre-auricular region, since 5 months. Radiology showed a 3.6 x 2.8cm, soft tissue mass, in the left temporo-parietal region extending into maxilla and orbit. Biopsy was sent for histopathological examination.

Microscopy

Fig.4a; H&E; 0.75x

Fig.4b; H&E; 10x

Fig.4c; H&E; 20x

Fig.4d; H&E; 20x

Fig.4e; H&E; 20x

Images show tissue cores infiltrated by a poorly differentiated tumor [Fig.4a & b]. Tumor cells are arranged in diffuse sheets and have large hyperchromatic nuclei, coarse chromatin, inconspicuous nucleoli and scant cytoplasm, exhibiting brisk mitosis [Fig.4c & d]. Some areas show sheets of these neoplastic cells exhibiting rhabdoid morphology [Fig.4e].

Fig.4f; LCA

Fig.4g; NKX2.2

Fig.4h; DESMIN

Fig.4i; MYOGENIN

Immunohistochemistry showed no expression with LCA [Fig.4f] & NKX2.2 [Fig.4g], while strong expression was noted with Desmin [Fig.4h] & Myogenin [Fig.4i].

Final Impression: Embryonal Rhabdomyosarcoma.

POINTS TO REMEMBER

• Age group:  Children and young adults (3-12 years)
• Sites: 
  • Head and neck (particularly orbit, nasopharynx, middle ear, oral cavity)
  • Retroperitoneum, Genitourinary tract, Bile ducts.
• Most common sites for metastasis:
  • Bone marrow, lungs, soft tissue, serosal surface
• Variants:
  • Sarcoma botyroides
  • Embryonal Rhabdomyosarcoma with anaplastic features
• Immunohistochemistry:
  • Positive stains: Myogenin (most sensitive and specific), MyoD1 & Desmin
  • CK and Neuroendocrine markers can be positive.
• Molecular:
  • Complex karyotypes(+2,+8,+13)
  • Loss of 11p15
• Prognosis:
  • Anaplasia is a negative prognostic factor, regardless of whether it is focal or diffuse.
• Differential diagnosis:
  • Alveolar and pleomorphic rhabdomyosarcomas
  • Desmoplastic small round cell tumor
  • Ewing/ PNET
  • Lymphoma
  • Monophasic synovial sarcoma
  • Neuroblastoma
  • Wilms tumor

Contributed by: Dr. Meenakshi Kamboj

Compiled by: Dr. Ankur Kumar & Dr. Himanshi Diwan

In case of queries, email us at: kumar.ankur@rgcirc.org

Embryonal rhabdomyosarcoma Head & Neck Pediatric tumors Rhabdomyosarcoma Soft tissue tumors

Last modified: 05/06/2021