Appendiceal Endometriosis with Intestinal Metaplasia Mimicking Appendiceal Mucinous Neoplasm – A Case Report and a Concise Review for the Practicing Pathologist

Mirela Chitul, Mădălina Chivu, Andrei Chitul, Ileana Popa, Gabriel Becheanu, D Cristian, Daniel Cristian, Florin Grama
International journal of surgical pathology · 2022 · vol. 31(4) , pp. 435–441 · doi:10.1177/10668969221105621 · PMID:35833324 · W4285386889
review OA: closed CC0 ⤵ 1 in-corpus citation
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⚙ AI-generated summary by claude@2026-06, 2026-06-11 ⓘ

This case report details appendiceal endometriosis with intestinal metaplasia mimicking a mucinous neoplasm, requiring immunohistochemistry to differentiate gland types.

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Abstract

Appendiceal endometriosis is a rare entity and, when accompanied by intestinal metaplasia, represents a challenging differential diagnosis with low-grade appendiceal mucinous neoplasm (LAMN). We present the case of a 47 years-old woman, with multiple surgical interventions for endometriosis, with persistent symptoms despite chronic hormonal treatment, with imaging showing stage IV endometriosis. Hence, en bloc low rectum resection with total hysterectomy and bilateral adnexectomy was performed, followed by appendectomy. Unexpectedly, despite the gross normal macroscopic appearance of the appendix, microscopy showed multiple endometriosis foci, consisting of endometrial glands embedded in varying amounts of endometrial stroma. As some of these glands were bordered by mucinous-type epithelium containing intestinal cells, Goblet cells, Paneth cells in addition to the presence of mucus-filled microcysts, immunohistochemistry (IHC) was performed in order to differentiate between intestinal-metaplasia and LAMN. IHC showed positivity of the endometrial epithelium for KRT7, estrogen receptor (ER) and progesterone receptor (PR). Both the appendiceal mucosa and the intestinal-type metaplastic epithelium of the glandular structures were positive for KRT20. Additionally, the endometrial stroma enclosing endometrial glands, as well as the stroma surrounding mucinous-type metaplastic epithelium, were positive for CD10, ER and PR. This patient's case draws attention to the rare occurrence of appendiceal endometriosis and the uncommon intestinal metaplasia, which can easily mimic LAMN, emphasizing the paramount importance of the differential diagnosis with this type of neoplasia.

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Condition tags

endometriosis

MeSH descriptors

Adenocarcinoma, Mucinous Adenocarcinoma, Mucinous Adenocarcinoma, Mucinous Adenocarcinoma, Mucinous Adenocarcinoma, Mucinous Adenocarcinoma, Mucinous Adenocarcinoma, Mucinous Adenocarcinoma, Mucinous Appendiceal Neoplasms Appendiceal Neoplasms Appendiceal Neoplasms Appendiceal Neoplasms Appendiceal Neoplasms Appendiceal Neoplasms Appendiceal Neoplasms Appendiceal Neoplasms Appendix Appendix Appendix Appendix

Citation neighborhood

Papers in the corpus that this work cites (lower rings, blue) and that cite this one (upper rings, green). Dot size scales with the paper's in-corpus citation count — bigger dot = more influential within the endo/adeno field. Click a dot to open that paper. [ expand to 2 hops ] — adds papers reached through this work's immediate citers/citees. Heavier; up to 60 extra dots.

References (15)

Cited by (1)

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