For urothelial carcinoma see the invasive urothelial malignancy topic.
Squamous Cell Carcinoma of the Bladder
Epidemiology
This malignancy is very common in areas with endemic Schistosomiasis infection, including South Africa and Egypt.
Aetiology and Pathogenesis
Schistosoma haematobium lives in the bloodstream of humans, and its eggs are excreted via the urine. There are several hypothesised ways it can cause malignancy:
- Chronic inflammation
- Altered metabolism of urinary products (including increased production of aromatic amines)
- Secondary infection of bacteria facilitated by presence of Schistosoma
Macroscopy
SCC of the bladder is usually a bulky tumour with both exophytic and invasive components
Microscopy
This tumour possesses no urothelial component - the presence of urothelial malignancy classifies this as a urothelial carcinoma with squamous differentiation. The typical features of SCC, such as keratin production and intercellular bridging, are present.
Prognosis
SCC of the bladder is staged in the same way as invasive urothelial tumour and seems to have equivalent results.
Adenocarcinoma of the Bladder
Incidence
Less than 2% of all bladder malignancies
Aetiology and Pathogenesis
Pure adenocarcinoma seems to have similar risk factors to urothelial malignancy.
Macroscopy
Many appearances are possible. A gelatinous appearance suggests a pure adenocarcinoma.
Microscopy
Glandular differentiation is seen. There is no evidence of urothelial malignancy.
Prognosis
These tumours typically present late and with invasion through or beyond the detrusor. 5 year survival is about 30%.
Small Cell Carcinoma of the Bladder
Incidence
No specific incidence data is available; fortunately this tumour is rare.
Aetiology and Pathogenesis
The pathogenesis is unknown. Neuroendocrine cells exist in the bladder epithelium but whether they are the cell of origin is debated.
Macroscopy
These tumours can exhibit a wide variety of appearances, but are usually diffusely infiltrating at the very least. About 5% occur in bladder diverticula.
Microscopy
The presence of any small cell component in a bladder malignancy results in a diagnosis of small cell carcinoma. This is in direct contrast to other malignancies (squamous cell carcinoma, adenocarcinoma), which are considered to be a variant of urothelial carcinoma if any urothelial carcinoma is present.
Cells are usually small and round with a large nuclear/cytoplasmic ratio. Mitoses are usually present. Neuroendocrine markers are positive in many of these tumours.
Prognosis
Small cell carcinoma of the bladder has a very poor prognosis with an 8% 5 year survival. The stage of disease at diagnosis and its effect on survival is debated. Systemic therapy is usually needed and may be effective.
