There have been few reports to date of vanishing gastric tumors
caused by anisakiasis [1]. The large intestine is rarely
affected because the ingested larvae usually do not travel that far down the
gastrointestinal tract. Colonic anisakiasis occasionally resembles a colonic
tumor, because it leads to edema, acute phlegmonous inflammation, or the
formation of granulomas around the larvae in the submucosa of the intestinal
wall [2].
A 77-year-old man attended our hospital for a positive fecal occult
blood test. He was asymptomatic. He had a history of appendectomy for acute
appendicitis at the age of 19 and ate raw fish almost every day. His white
blood cell count was normal with no eosinophilia. At colonoscopy, a clearly
demarcated, depressed lesion with raised margins (similar to a Borrmann type 2
lesion) was identified in the cecum ([Fig. 1]).
Fig. 1 Colonoscopy showing a
lesion in the cecum, similar to a Borrmann type 2 lesion.
The histopathological examination of the biopsy specimens revealed
eosinophilic infiltration of the lamina propria mucosae and the submucosa, and
necrosis of the epithelium ([Fig. 2]).
Fig. 2 Histopathological
section of the biopsy specimen showing eosinophilic infiltration in the lamina
propria mucosae and necrosis of the epithelium.
Malignant cells were not seen. Computed tomography showed wall
thickening in the cecum ([Fig. 3]).
Fig. 3 Computed tomography scan
showing cecal wall thickening and the “dirty fat” sign around the
lesion.
On repeat colonoscopy after 16 days, the tumour resembling a
Borrmann type 2 lesion had disappeared and a reddish scar with small erosion
was seen in the cecum ([Fig. 4]).
Fig. 4 Repeat colonoscopy
showing disappearance of the tumor and a reddish scar with a small erosion in
the cecum.
Serum titers of both IgG and IgA antibodies to Anisakis larvae on the day of the second colonoscopy were
slightly elevated at 1.61 (cut-off index, normal < 1.50). At
another colonoscopy a year later, the tumor had completely disappeared and a
whitish scar was seen in the cecum ([Fig. 5]).
Fig. 5 Colonoscopy after a year
showing a whitish scar but no evidence of tumor.
The vanishing tumor may be considered to be anisakiasis of the
cecum.
Endoscopy_UCTN_Code_CCL_1AD_2AZ
