Endoscopic submucosal dissection (ESD) is a reference method for the management of extensive lesions of the digestive tract. Its development extended the indications of ESD to lesions that were previously difficult to treat such as recurrences, lesions invading a diverticulum or the appendix, and submucosal lesions that may not be treatable by endoscopic mucosal resection [1] [2].

Colonic submucosal lesions are common, and their definitive diagnosis can be problematic. En bloc resection is essential in cases of submucosal tumors because of the potential for such to be carcinoid tumors or gastrointestinal stromal tumors (GISTs), and careful histological analysis is required [3] [4]. The submucosal nature of these lesions makes classic ESD challenging.

We report here the case of a 75-year-old patient in whom a submucosal lesion in the right colon was detected during a screening colonoscopy ([Fig. 1]). The submucosal lesion was < 1 cm in diameter. Previous biopsies yielded ambiguous findings. We hypothesized that the patient had a GIST or carcinoid tumor, and so we performed resection by ESD to facilitate diagnosis and, potentially, be curative.

After injection and circumferential incision, traction using the double-clip traction method [5] was performed to ensure complete resection ([Fig. 2]). This method showed a small submucosal space immediately beneath a hard, whitish submucosal lesion ([Video 1]). The patient was discharged the day after the resection and did not develop any complications. Histopathological analysis revealed an unexpected diagnosis of a submucosal nematode with an inflammatory reaction as a gigantocellular epithelioid granuloma with free lateral and deep margins ([Fig. 3], [Fig. 4]).

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Article published online:
21 November 2022

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