# A Large Gastrointestinal Tumor With Cystic Degeneration Initially Mistaken for Gastric Splenosis: A Case Report

## TL;DR

A 63-year-old woman's gastrointestinal tumor was initially mistaken for splenosis due to its unusual appearance, but was later correctly diagnosed as a GIST with cystic degeneration.

## Contribution

This case report highlights the diagnostic challenges of atypical GISTs and the importance of endoscopic ultrasound for accurate diagnosis.

## Key findings

- A gastrointestinal stromal tumor with cystic degeneration was misdiagnosed as splenosis on imaging.
- Endoscopic ultrasound with tissue acquisition confirmed the correct diagnosis of GIST.
- The tumor had negative margins and no evidence of metastasis.

## Abstract

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract and usually present as submucosal gastric lesions. Atypical morphologies, such as exophytic or cystic growth, are uncommon and can lead to lesions being mistaken for hepatic, pancreatic, or splenic origin. We report a case of a 63-year-old woman referred for evaluation of unexplained weight loss. Imaging revealed a 4 cm lobulated lesion adjacent to the spleen with peripheral cystic changes. The mass enhanced similarly to splenic tissue and was initially interpreted as splenosis. Final pathology revealed a GIST with cystic degeneration, negative margins, and no evidence of metastasis. This case highlights the diagnostic challenges posed by atypical GISTs and emphasizes the importance of endoscopic ultrasound (EUS) with tissue acquisition for accurate diagnosis when cross-sectional imaging is inconclusive.