A Case Report-Extra Luminal Rectal GIST Mimicking Leiomyoma: Diagnostic Insight from CD117, DOG1, and Ki-67 Profiling

DOI

10.2991/978-94-6463-966-7_6How to use a DOI?

Keywords

gastrointestinal stromal tumor (GIST); rectum; extra-luminal; CD117; DOG1

Abstract

Gastrointestinal stromal tumors (GISTs) represent the most prevalent mesenchymal neoplasms within the gastrointestinal tract, predominantly located in the stomach and small bowel. Rectal GISTs are uncommon, and extra-luminal presentations are exceedingly rare. Such cases may histologically resemble other spindle cell neoplasms, particularly leiomyomas, which can complicate accurate diagnosis. Immunohistochemistry (IHC) is essential for definitive identification. A 67-year-old woman presented with a large pelvic mass originating from the extra-luminal region of the rectum. Grossly, two firm, grey-brown tumor masses were resected, measuring (11 × 9 × 6) cm and (30 × 14 × 7) cm. The principal tumor was well-circumscribed, measuring (14 × 8 × 7) cm. Microscopically, it consisted of spindle cells arranged in fascicles, featuring blunt-ended nuclei and eosinophilic cytoplasm, accompanied by hyalinization and focal interstitial hemorrhage. Due to its morphological resemblance to leiomyoma, IHC was performed using CD117, DOG1, and Ki-67. The tumor exhibited diffuse cytoplasmic positivity for CD117 and DOG1, consistent with GIST. The Ki-67 proliferation index was below 3%, indicating low mitotic activity. No residual tumor was observed at the resection margins. The surrounding mucosa and submucosa were histologically unremarkable. This case highlights the diagnostic challenge posed by extra-luminal rectal GISTs that mimic leiomyomas. Immunohistochemistry, particularly CD117 and DOG1, is indispensable in differentiating GISTs from histological mimics. Low Ki-67 expression further supports a low-risk classification. Awareness of such atypical presentations is critical for achieving diagnostic accuracy and guiding appropriate management.

Copyright

© 2025 The Author(s)

Open Access

Open Access This chapter is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

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TY  - CONF
AU  - Lidya Imelda Laksmi
AU  - Adi Muradi
AU  - Jessy Chrestella
AU  - Betty Betty
AU  - Ihsan Primananda Prayoga
PY  - 2025
DA  - 2025/12/25
TI  - A Case Report-Extra Luminal Rectal GIST Mimicking Leiomyoma: Diagnostic Insight from CD117, DOG1, and Ki-67 Profiling
BT  - Proceedings of the 8th International Conference on Neuroscience, Neurology, and Psychiatry 2025 (ICONAP 2025)
PB  - Atlantis Press
SP  - 39
EP  - 44
SN  - 2468-5739
UR  - https://doi.org/10.2991/978-94-6463-966-7_6
DO  - 10.2991/978-94-6463-966-7_6
ID  - Laksmi2025
ER  -