Extrapulmonary Small Cell Carcinoma of the Bladder
Section snippets
Epidemiology
Although the true incidence of small cell cancer of the urinary bladder is unknown, many retrospective case series report an incidence between 0.3% and 1%.3, 5, 6, 17, 18, 19 In a retrospective review of 552 consecutive bladder cancer patients, only six patients had a diagnosis of small cell carcinoma.17 Similarly, Hind et al reported three patients with small cell carcinoma in 110 cystectomy specimens.19 In China, of 334 cases of bladder cases reviewed over a 6-year period, only two cases of
Histology
The origin and histogenesis of small cell cancer in the urinary bladder remains unclear. Many theories have been proposed. Nevertheless, one must account for the mixed histologic pattern that is commonly seen in these tumors. It was earlier believed that this neoplasm arises either from Kultchitsky type cells of the bladder wall or from a metaplastic mucosal epithelium; however, the most widely accepted view is that small cell carcinoma of the bladder arises from transformation of totipotent
Clinical Features
The majority of patients present with painless gross hematuria.1, 3, 6, 10, 17, 37 Less frequent symptoms include microscopic hematuria, passage of blood clots, dysuria, nocturia, hematospermia, bladder irritability, supra-pubic pain and cramps, diffuse abdominal pain, and obstruction of the ureteric orifice causing hydroureter and hydronephrosis, as well as bladder outlet obstruction producing urinary retention and acute renal failure.3, 6, 15, 20, 37, 39, 47, 48, 49, 50, 51 A case of small
Diagnosis
In the era before computed tomography (CT) scanning, gross hematuria was evaluated by intravenous pyelography (IVP).41 The presence of a filling defect in the urinary bladder was suggestive of bladder pathology.20, 26, 41, 56, 57, 58 Additional radiologic findings noted are calcifications in the tumor, nonvisualization of the ureter, ureteric obstruction, hydroureter, and hydronephrosis.17, 32, 52, 53, 59, 60, 61 Similar information was also obtained from a retrograde pyelogram.57 These
Staging
All new cases of bladder small cell cancer should be staged with chest, abdomen, and pelvic CT scans. Magnetic resonance imaging (MRI) of the brain and a bone scan may be reserved for specific situations.
CT of the chest is required to eliminate a primary pulmonary small cell carcinoma since bladder metastases from a lung primary have been observed.77, 78 CT of the pelvis or MRI of the pelvis delineates bladder tumors from surrounding structures and may help in planning surgical resection.50, 51
Treatment
There is no consensus on the standard approach to treat small cell carcinoma of the bladder. Due to the rarity of the disease, prospective clinical trials have not been performed; hence recommendations for managing these tumors have been extrapolated from individual case reports, retrospective reviews of case series, and treatment of small cell carcinoma of the lung. Nonetheless, it is apparent that without treatment, the disease is rapidly fatal.24, 26, 49
For early T-stage tumors, surgical
Prognosis
Despite early treatment, the majority of patients die of their disease.3, 83, 91 The prognosis is worse than poorly differentiated transitional cell carcinoma of the bladder.11 Fourteen of 18 patients had died at a median follow-up of 9 months.11 The over all median survival in the Mayo Clinic series was 1.7 years with recurrences in regional lymph nodes or distant disease.3 Few patients were alive beyond 5 years. Mangar et al reported only one survivor at 7 years after diagnosis among 14
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