Arises from undifferentiated mesenchymal tissue.
10 – 15 % of solid tumours in children.
20 – 30 % of rhabdomyosarcomas arise from genitourinary tract – bladder, prostate, vagina, uterus or paratesticular.
Bimodal distribution – 2-4 years, then 15 – 19 years.
Majority are sporadic – but associated with Li Fraumeni or neurofibromatosis type 1.
Other risk factors – high birth weight, LGA, advanced maternal age, maternal drug use
Pathology
Two main categories – embryonal and alveolar – majority of GU tumours are embryonal (better prognosis cf. alveolar)
Typical characteristic feature is early differentiation towards skeletal muscle phenotype.
Described as ‘botryoid’ variant – like a bunch of grapes.
Disseminates mostly by local spread – lymphatic (20 %) and metastasis (10 %) less common.
Presentation
May be variable:
- Urinary symptoms or urinary retention, haematuria, constipation
- Abdominal pain or mass
- Paratesticular/scrotal painless mass
- Protruding botryoid vaginal mass
Work up and investigation
Usually appropriate imaging – CT, MRI, chest imaging, ultrasound.
Bloods including FBC and renal function.
Biopsy – percutaneously, or transurethrally, depending on circumstances.
Assess for metastatic disease – locoregional LNs.
Management
Multidisciplinary
Usually initially treated with chemotherapy – various combinations of vincristine, actinomycin, cyclophosphamide and ifosfamide.
Radiation including brachytherapy may be used post-operative for residual disease or difficult to operate cases.
Surgery, usually following chemo, may be organ sparing or radical depending on site.
- Radical inguinal orchidectomy for paratesticular cases.
- Partial cystectomy vs cystectomy vs cystoprostatectomy
Prognostic factors:
> 10 years at presentation is worse
Embryonal variant is better than alveolar
Vaginal/paratesticular better prognosis than bladder/prostate
Larger tumours / higher stage worse, involved lymph nodes worse
PAX/FOXO1 genes on histology associated with worse survival.
Overall survival around 80 % for prostate/bladder, better for paratesticular.
Bladder sparing surgery may be associated with significant morbidity in terms of urinary symptoms and incontinence.