Distinction of high-grade neuroendocrine carcinoma/small cell carcinoma from conventional urothelial carcinoma of urinary bladder: An immunohistochemical approach

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15 Scopus citations

Abstract

CONTEXT: High-grade neuroendocrine carcinomas and small cell carcinomas (HGNEC/SmCC) of the urinary bladder are uncommon but aggressive neoplasms. Differentiation of HGNEC/SmCC from high-grade urothelial carcinoma (UC) is based on histomorphologic features, but can be difficult in small biopsies and cases with mixed morphology. OBJECTIVE: We attempt to identify a limited immunohistochemical panel that aids in this distinction. DESIGN: We selected 39 cases of bladder carcinoma with small cell morphology: 7 HGNEC/SmCC, 21 high-grade UC with neuroendocrine-like pattern, and 11 mixed neoplasms. Immunohistochemistry for pan-cytokeratin, synaptophysin, chromogranin, p63, and thyroid transcription factor-1 was performed. RESULTS: Pan-cytokeratin was positive in 6 of 7 cases (86%) of the HGNEC/SmCC group. All 7 tumors were positive for synaptophysin, 6 of them were negative for p63 and chromogranin, and 1 was positive for p63 and chromogranin. All 21 high-grade UC with neuroendocrine-like pattern of growth showed positive staining for pan-cytokeratin, and were all negative for synaptophysin and chromogranin. Sixteen (76%) of high-grade UC were also positive for p63. All 11 mixed tumors were positive for pan-cytokeratin. In 10 of the 11 mixed tumors (91%), synaptophysin was positive in the neuroendocrine differentiated areas and it was negative in the urothelial component. In 2 of the 11 mixed tumors (18%) chromogranin was also positive. Three (27%) of the 11 mixed cases were positive for p63 in the UC foci. Chromogranin was negative in 6 of the pure HGNEC/SmCC and in 8 of the mixed tumors. None of the 39 samples were reactive for thyroid transcription factor-1. CONCLUSIONS: A limited immunohistochemical panel including pan-cytokeratin, synaptophysin, and p63 discriminates HGNEC/SmCC from high-grade UC.

Original languageEnglish (US)
Pages (from-to)395-399
Number of pages5
JournalApplied Immunohistochemistry and Molecular Morphology
Volume19
Issue number5
DOIs
StatePublished - Oct 1 2011

Keywords

  • chromogranin
  • high-grade neuroendocrine
  • p63
  • pan-cytokeratin
  • small cell carcinoma
  • synaptophysin
  • thyroid transcription factor-1

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Medical Laboratory Technology
  • Histology

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