Because of the low incidence of small cell carcinoma of the urinary bladder, a second opinion was taken on histopathology and immunohistochemistry and they also confirmed SCCB of the urinary bladder.
SCCB is rare, and there is no standard treatment for it.
The group drafted a consensus guideline to address issues of diagnosis, staging, treatment and follow-up of SCCB (SCC of the prostate was also discussed and this consensus guideline will be presented at a later date).
The first case of primary SCCB was reported in 1981;[sup.
22,32] These paraneoplastic syndromes appear less common in SCCB compared to SCC of the lung or prostate.
The differential diagnosis of SCCB is quite broad and includes poorly differentiated urothelial carcinoma, poorly differentiated squamous cell carcinoma, lymphoma, lymphoepithelioma-like carcinoma, plasmacytoid carcinoma, large cell neuroendocrine carcinoma, SCLC metastatic to the bladder or SCC of the prostate invading into the bladder.
34] and SCLC share similar histology, the diagnosis of SCCB is based on the same World Health Organization (WHO) criteria.
Immunohistochemical staining is important to support a diagnosis of SCCB, which typically exhibits both epithelial and neuroendocrine differentiation.
2 or CK8/18, can be positive in both SCCB and UCB, but often have different staining patterns: SCCB usually stains in a punctate perinuclear pattern, while UCB stains in a membranous pattern.
48] Both SCLC and SCCB can be CK7 positive and are usually CK20 negative.