Bladder & urothelial tract
Other tumors
Rhabdomyosarcoma
Author: Nat Pernick, M.D.
Last author update: 1 November 2015
Last staff update: 15 November 2021
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: Bladder rhabdomyosarcoma
Table of Contents
Definition / general | Epidemiology | Sites | Etiology | Clinical features | Prognostic factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Positive stains | Negative stains | Molecular / cytogenetics description | Differential diagnosisCite this page: Pernick N. Rhabdomyosarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bladderrhabdo.html. Accessed April 25th, 2024.
Definition / general
- Sarcoma with features of skeletal muscle differentiation
- Either embryonal (botryoid or spindle cell), alveolar or pleomorphic rhabdomyosarcoma
Epidemiology
- Less than 0.5% of all bladder tumors, but one of most common tumors of the lower urogenital tract in children
- Often children 2-6 years old; 75% male
- Adult tumors are usually alveolar or unclassified, commonly with anaplasia, and resemble small cell carcinoma (Am J Surg Pathol 2008;32:1022)
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Botryoid variant:
- Occurs in mucosal lined, hollow cavities (vagina, nasal cavity, bladder); most common bladder tumor in children
- May be associated with Wilms tumor and Dandy-Walker syndrome
Sites
- Usually in trigone
- Infiltrates adjacent tissue but distant metastases are rare
Etiology
- Arise from primitive muscle cells
Clinical features
- 5 year survival for embryonal subtype is 50-80% (BJU Int 2010;106:557, Pediatr Blood Cancer 2011;56:718)
- Adult tumors are uniformly aggressive
Prognostic factors
- Favorable prognostic factors: children vs. adults, embryonal histology, low stage, polypoid (exophytic) growth pattern [10 year survival is 92% vs. 68% for diffuse intramural (endophytic) growth pattern]
Case reports
- Antenatally diagnosed rhabdomyosarcoma of the bladder treated without extensive surgery (Nat Rev Urol 2009;6:449)
- 3 year old girl with primary embryonal rhabdomyosarcoma (Arch Pathol Lab Med 2004;128:357)
Treatment
- Surgery and chemotherapy
- Recurs if inadequately excised
- May die even after chemotherapy induced maturation (Am J Surg Pathol 2001;25:856)
Gross description
- Mucoid, polypoid
- Botryoid tumors resemble a bunch of grapes
Microscopic (histologic) description
- Myxomatous stroma with scattered, small, blue malignant cells, usually compressed beneath intact urothelium (cambium layer)
- Cross striations are often difficult to identify in untreated cases
Positive stains
- Muscle specific actin, desmin
- Myogenin and MyoD1 in well differentiated tumors
Negative stains
- Myoglobin (usually), keratin (usually), calponin, h-caldesmon
- ALK1 (Mod Pathol 2007;20:592)
Molecular / cytogenetics description
- Alveolar subtype has translocations between #13 FKHR gene and either #2 - PAX3 or #1 - PAX7 gene
- Embryonal subtype has 11p-
Differential diagnosis
- Carcinomas (urothelial or small cell) with rhabdomyosarcomatous differentiation:
- Have distinct epithelial component
