Soft tissue
Skeletal muscle
Ectomesenchymoma
Author: Kenneth A. Iczkowski, M.D.
Last author update: 1 December 2017
Last staff update: 25 July 2023
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: Ectomesenchymoma
Table of Contents
Definition / general | Essential features | Sites | Clinical features | Radiology description | Prognostic factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Molecular / cytogenetics description | Differential diagnosis | Board review style question #1 | Board review style answer #1Cite this page: Iczkowski KA. Ectomesenchymoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissueectomes.html. Accessed November 28th, 2024.
Definition / general
- Ectomesenchymoma is a rare, fast growing tumor of the nervous system or soft tissue that occurs mainly in children
Essential features
- 2 histologic components (see microscopic (histologic) description below)
Sites
- Sites described most often include head / neck, abdomen, perineum, scrotum and limbs
Clinical features
- Fast growing tumors that eventually cause pain
Radiology description
- CT scan may show anterior displacement of bladder and rectal compression
Prognostic factors
- Stage and size < 10 cm
Case reports
- 5 month old boy with a 7.5 cm mass emanating from the prostate (Pediatr Surg Int 1999;15:68)
- Tumor was resected and after a course of chemotherapy, recurred 8 months later, causing fatal intestinal obstruction
- This is the only case report of ectomesenchymoma of the prostate
Treatment
- Surgery and chemotherapy have been described; prognosis is guarded
Gross description
- Rubbery, white
Microscopic (histologic) description
Microscopic (histologic) images
Contributed by Brendan C. Dickson, M.D., M.Sc.
Spindle cells and neuronal elements
Rhabdomyoblastic differentiation and mitoses
Myogenin
Synaptophysin
Images hosted on other servers:
Male infants with pelvic / urogenital tumors
34 year old man with paratesticular tumor
Positive stains
- Skeletal muscle component is positive for desmin and muscle specific actin
- Ganglioneuroma component is positive for S100 protein and the ganglion cells stain for neuron specific enolase
Negative stains
Molecular / cytogenetics description
- Cytogenetics are similar to embryonal rhabdomyosarcoma
Differential diagnosis
- Differential diagnosis includes rhabdomyosarcoma (RMS) because of the skeletal muscle component; this was the initial diagnosis in the reported case (Pediatr Surg Int 1999;15:68) after transrectal biopsy
- Ganglion cells may not be identified on needle biopsies owing to sampling variation
- For further discussion, see Crit Rev Clin Lab Sci 2003;40:429
Board review style question #1
Which of the following is true of ectomesenchymoma of the prostate?
- It has 3 histologic components
- It is S100 positive in the neural component
- It is a slow growing tumor
- It should be cytokeratin positive
- It should be negative for desmin
Board review style answer #1
