Primary mixed adenocarcinoma and small cell carcinoma of the appendix: A clinicopathologic, immunohistochemical, and molecular study of a hitherto unreported tumor

Giulio Rossi, Federica Bertolini, Giuliana Sartori, Nazzarena Bigiani, Alberto Cavazza, Moira Foroni, Riccardo Valli, Guido Rindi, Carmela De Gaetani, Gabriele Luppi

Research output: Contribution to journalArticlepeer-review

Abstract

Appendiceal carcinoids range from well-differentiated endocrine tumor to well-differentiated endocrine carcinoma, while poorly differentiated (small cell) carcinoma has not been described in this site. We report herein a case of mixed intestinal-type adenocarcinoma associated with a small cell carcinoma arisen in a 35-year-old woman and clinically presenting as an appendiceal abscess. The resected tumor histologically appeared as a biphasic lesion composed of a nonmucinous adenocarcinoma closely juxtaposed with a poorly differentiated (small cell) endocrine carcinoma. The subsequent right hemicolectomy was unremarkable, but one pericolic lymph node showed a metastatic deposit consisting of the adenocarcinoma only. The patient thus underwent a chemotherapeutic protocol for colorectal cancer, and she is alive and well at the 65-month follow-up. Immunohistochemically, the adenocarcinoma strongly stained for cytokeratin 20 and carcinoembryonic antigen, while the endocrine component displayed a dot-like positivity for pan-cytokeratins and chromogranin. Of note, both components did not stain with CDX2 and p53. At genotypic analysis by microsatellite instability, both components shared many microsatellite alterations as well as a normal p53 gene setup, although small cell carcinoma harbored additional alterations. Clinical and molecular findings led us to consider this lesion as a clonal tumor in which the endocrine component seems to derive from a progressive differentiation of the adenocarcinoma following a glandular-to-endocrine sequence.

Original languageEnglish
Pages (from-to)1233-1239
Number of pages7
JournalAmerican Journal of Surgical Pathology
Volume28
Issue number9
DOIs
Publication statusPublished - Sep 2004

Keywords

  • Adenocarcinoma
  • Appendix
  • Combined tumor
  • Loss of heterozygosity
  • Microsatellite
  • Small cell carcinoma

ASJC Scopus subject areas

  • Anatomy
  • Pathology and Forensic Medicine

Fingerprint Dive into the research topics of 'Primary mixed adenocarcinoma and small cell carcinoma of the appendix: A clinicopathologic, immunohistochemical, and molecular study of a hitherto unreported tumor'. Together they form a unique fingerprint.

Cite this