A 31-year-old man presented with a feeling of compression and intermittent pain in
the epigastrium. He had eaten sliced raw fish (sashimi) for dinner at 10 pm on the
previous night and developed epigastric symptoms 2 hours thereafter. Physical examination
revealed no tenderness or rebound tenderness in the epigastrium; his vital signs and
laboratory parameters were normal. He reported a history of similar epigastric symptoms
when he had had gastric anisakiasis; therefore, esophagogastroduodenoscopy (EGD) was
conducted. This revealed an Anisakis larva invading the mucosa of the distal esophagus,
where a granulomatous reddish nodule approximately 2 mm in diameter was observed ([Fig. 1]). Magnifying endoscopy with narrow-band imaging (NBI) showed a rather flattened,
smooth, and brownish nodule without vascular structure or surface pattern ([Fig. 2 a]). Closer view of the larva revealed a small whitish elongated spot (the ventricle,
an organ distally adjacent to the esophagus of Anisakis larva), which is seen more
clearly than with conventional white-light endoscopic observation ([Fig. 2 b]). After removing the parasite using biopsy forceps ([Video 1]), his symptoms reduced immediately. At the 1-month follow-up EGD, the nodule had
disappeared.
Fig. 1 Esophagogastroduodenoscopy image showing an Anisakis larva invading the mucosa of
the distal esophagus. At the invading site, a granulomatous reddish nodule approximately
2 mm in diameter is observed (arrowheads).
Fig. 2 Magnifying endoscopy with narrow-band imaging showing: a a nodule that is round, rather flattened, and smooth, with neither vascular structure
nor surface pattern of the brownish lesion; b on closer view of the Anisakis larva, a small whitish elongated spot (arrows) that
is seen more clearly than on conventional white-light endoscopic observation (the
whitish spot corresponds to the ventricle that is an organ distally adjacent to the
esophagus of Anisakis larva).
Video 1 Endoscopic observation of an Anisakis larva invading the esophageal mucosa using
conventional white-light imaging and magnifying endoscopy with narrow-band imaging;
thereafter, endoscopic removal of the larva is performed with biopsy forceps.
Anisakis infection most commonly affects the stomach and the small intestine [1]. Anisakiasis confined to the esophagus is very rare; only four cases have been reported
thus far in the English literature [2]
[3]
[4]
[5]. To our knowledge, this is the first case report that showed a nodular lesion of
esophageal mucosa penetrated by an Anisakis larva, although it is well known that
gastric anisakiasis may cause a tumor-like nodule or mass (also called “vanishing
tumor”). When gastrointestinal symptoms that occur after a history of consumption
of raw or undercooked fish or squid suggest Anisakis infection, not only the stomach
and the duodenum but also the esophagus should be thoroughly examined endoscopically.
A study of further cases is needed to clarify whether the nodular lesion, as seen
in our case, is common in esophageal anisakiasis.
Endoscopy_UCTN_Code_CCL_1AB_2AG_3AD
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