Clin Endosc.  2014 Sep;47(5):460-463. 10.5946/ce.2014.47.5.460.

Endoscopic Ultrasound-Guided Sampling of a Metastatic Mucinous Adenocarcinoma Mimicking a Gastric Subepithelial Tumor

• Seo DC
• Lee TH
• Jeen YM
• Kim HG
• Kim EB
• Lee SC

• KMID: 2165381
• DOI: http://doi.org/10.5946/ce.2014.47.5.460

Abstract

Metastatic mucinous adenocarcinoma of appendix origin and mimicking a gastric subepithelial tumor (SET) is very rare. Endoscopic ultrasound (EUS)-guided sampling is a useful diagnostic method for SETs. However, the cytologic findings of metastatic mucinous adenocarcinoma are unfamiliar to many pathologists and gastroenterologists. These findings present a diagnostic challenge because the introduction of gastric epithelium and mucin into the specimen during the procedure can be misleading. This is the first reported experience of an EUS-guided sampling of a gastric SET in a patient with suspected appendiceal tumor, to make the diagnosis of a mucinous adenocarcinoma.

Keyword

Appendix; Endosonography; Biopsy, fine-needle; Adenocarcinoma, mucinous; Stomach

MeSH Terms

Adenocarcinoma, Mucinous*
Appendix
Biopsy, Fine-Needle
Diagnosis
Endosonography
Epithelium
Humans
Mucins
Stomach
Ultrasonography
Mucins

Figure

• 

  Fig. 1 Endoscopy, endoscopic ultrasound (EUS), and EUS-guided sampling of the gastric subepithelial tumor (SET). (A) Posterior portion of a dumbbell-shaped SET is noted on the antrum with a normal overlying mucosa. (B) Forceps biopsy is performed in the linear ulcer on the surface of anterior portion of the SET. (C) The hypoechoic mass with an amorphous shape has invaded into the gastric wall layers, and is accompanied with multiple anechoic portions with variable sizes. (D) EUS-guided ProCore needle biopsy is performed on the lesion.

• 

  Fig. 2 Pathologic findings of the gastric subepithelial tumor. (A) Lower-power view of the endoscopic ultrasound-guided sampling depicts several branching vasculatures with folded sheets of bland-looking mucinous epithelial cells (H&E stain, ×100). (B) Some of the mucinous cells show nuclear pleomorphism and hyperchromasia, suspicious for malignancy (H&E stain, ×400). (C) The serosa of the resected appendix shows extension of the mucinous adenocarcinoma with several acellular mucin pools (H&E stain, ×40). (D) There are a few glands of metastatic mucinous adenocarcinoma with surrounding inflammation and fibrosis in the omentum. Several acellular mucin polls are also seen (H&E stain, ×100).

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