Acellular mucin in pseudomyxoma peritonei of appendiceal origin: What is adequate sampling for histopathology?

Marwa Al-Azzawi, Joseph Misdraji, Marie Louise F. Van Velthuysen, Jinru Shia, Melissa W. Taggart, Rhonda K. Yantiss, Magali Svrcek, Norman Carr

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Introduction Acellular intra-abdominal mucin is associated with a favourable prognosis in pseudomyxoma peritonei. There are no current guidelines on how many blocks are needed to classify the mucin as acellular with confidence. Methods Specimens from cytoreductive surgery for mucinous appendiceal neoplasia, in which acellular mucin was found on initial histopathological examination, were prospectively identified. Additional tissue blocks were then taken to include either all residual visible intra-abdominal mucin or a maximum of 30 blocks. We also sent a questionnaire to pathologists in other centres. Results Twelve patients were identified. In two cases, neoplastic epithelial cells were found on taking additional blocks. The questionnaire results suggested considerable variation in block-taking practice. Conclusion Taking additional tissue identified neoplastic cells in 2 of 12 cases. We recommend that sampling additional material should be considered when only acellular mucin is found on initial histology. Further work to determine the optimum sampling protocol is indicated.

Original languageEnglish (US)
Pages (from-to)220-222
Number of pages3
JournalJournal of Clinical Pathology
Issue number4
StatePublished - Apr 1 2020


  • appendix
  • histopathology
  • malignant tumours
  • peritoneum

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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