Teaching Case

A 3-year-old boy with history of dysuria, presented with increased frequency and urgency for 3 weeks that progressively worsened, but without fever. A physical examination revealed distended bladder. The urine test was positive to erythrocytes and urine culture was negative.

Ultrasound examination demonstrated a solid bladder mass of 3 cm size, arising from the bladder neck. The lesion had a heterogeneous echotexture and lobulated contours. Colour Doppler showed high vascular flow in the mass. There was a degree of bilateral hydronephrosis. CT confirmed the ultrasound appearances. The lesion proved to be an embryonal rhabdomyosarcoma. Metastatic workup was negative. The boy was treated with surgery, chemotherapy and radiotherapy.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in the paediatric population. Twenty percent arise from the genitourinary system, usually the prostate, bladder, paratesticular area and vagina; the trigone of the bladder and the prostate being the most common locations [1, 2]. There is a bimodal age distribution with a peak incidence at the ages of 2-4 years and 15-19 years [3]. RMS of bladder usually manifests during the first 3 years of life, and the patients are mostly male [4].

There are three histological subtypes of RMS: embryonal, alveolar and pleomorphic. The embryonal type is the most common and has a favourable prognosis, the pleomorphic type rarely occurs in children [1, 4]. RMS botryoid is a polipoid form of embryonal histology that occurs in hollow organs such as the bladder and vagina [3].

The clinical presentation of a child with bladder RMS include urinary retention, urgency, frequency or incontinence and gross haematuria [1, 3]. On physical examination, a distended bladder is frequently found or an abdominal mass may be present [1]. Metastatic disease occurs most commonly in the lungs, cortical bone and lymph nodes and less frequently in the bone marrow and liver [4].

The first option to evaluate a child with a suspected RMS is ultrasound. This study can confirm the existence of an intraluminal mass with a solid hyperechoic or hypoecechoic component, and may contain focal anechoic areas representing haemorrhage or necrosis [2, 4]. At Doppler Colour Flow test, the lesions often show vascularization with high flow velocity during the diastolic phase inside and around the edge of the mass [2, 4].

CT is useful to evaluate the extent of associated inguinal and retroperitoneal lymph node enlargement and for the detection of pulmonary metastases [4]. MR imaging allows accurate assessment of local extent of the tumour, although the precise location of the tumour is often difficult to identify as the disease infiltrates adjacent structures [2, 4]. CT or RM can be used to help assess the efficacy of primary chemotherapy [5].

The initial procedure is to obtain adequate tissue for a definitive diagnosis, usually a biopsy [3, 5]. Multimodality treatment with surgery, chemotherapy and radiation therapy is the current approach, although the appropriate timing, extent and intensity of these options remains controversial [3, 4]. The goal is to preserve the bladder without adversely impacting survival [5].