Occult gastric cancer with distant metastasis proven by random gastric biopsy.

Krukenberg tumor, a rare metastatic ovarian tumor arising from gastrointestinal adenocarcinoma mainly, tends to occur in premenopausal females. Finding the origin of a Krukenberg tumor is crucial for determining prognosis. In Eastern countries, the most common origin of Krukenberg tumor is stomach cancer, which is generally diagnosed via endoscopic biopsy to investigate an abnormal mucosal lesion. Here, we describe a case of huge adnexal mass in a 33-year-old woman who presented with abdominal distension. Two independent endoscopic examinations performed by experts in two tertiary university hospitals revealed no abnormal mucosal lesion. The patient was diagnosed with a Krukenberg tumor according to findings from random endoscopic biopsies taken from normal-looking gastric mucosa in our hospital. It is very rare to be diagnosed via a random biopsy in cases where three well-trained endoscopists had not found any mucosal lesion previously. Thus, in this case, random biopsy was helpful in finding the origin of a Krukenberg tumor.