Krukenberg Tumor of the Ovary with an Occult Primary Carcinoma: A Rare Entity

Introduction

Krukenberg tumor is rare, accounting for 1%–2% of all ovarian tumors. In 1896, Friedrich Krukenberg (1871–1946), a German gynecologist and pathologist, described what he presumed was a new type of primary ovarian neoplasm. The true metastatic nature of this lesion was established 6 years later. The stomach is the primary site in most Krukenberg tumor cases (70%). ¹ The primary carcinoma in Krukenberg tumors is sometimes clinically occult. Thorough examination of the gastrointestinal tract and other sites may also fail to reveal the primary carcinoma. The primary carcinoma sometimes may remain undetected for several years after oophorectomy. ² A case of Krukenberg tumor with occult primary, which could not be detected even after a thorough examination, is described here.

Case

A 52-year-old woman presented with complaints of abdominal pain of 1 month's duration and a single episode of postmenopausal bleeding 15 days prior. Findings from the general physical examination were normal, and a pelvic examination revealed bilateral ovarian masses 10×10 cm in size, solid in consistency, mobile, nontender, and with irregular margin. A pelvic sonogram suggested that ovarian masses were malignant. All other abdominal organs were normal on ultrasound. CA-125 was 945 international units (IU)/mL. Computed tomography (CT) scan revealed a large well-defined mass lesion with heterogeneous solid and cystic components in both uterine adenexa measuring 18×10.5 cm and 11×7 cm, on the right and left sides, respectively. Other abdominal organs were normal. Exploratory laparotomy followed by partial omentectomy, total abdominal hysterectomy, bilateral salpingo-oophorectomy, and peritoneal washing were performed. Remaining abdominal structures including the stomach and intestines were thoroughly visualized and palpated and felt to be normal. No ascitis was present. On gross examination, ovarian tumors measured 17×11×9 cm and 12×8×5 cm, on the left and right sides, respectively. Both ovarian tumors were bosselated with an irregular outer surface (Fig. 1). The cut surface showed lobulated, gray-white to yellowish color with a few cysts filled with serous fluid. Microscopic examination of the sections from both ovaries showed mucin-laden signet ring cells, within a cellular ovarian stroma (Fig. 2). The cytoplasm of these cells varied from a granular eosinophilic to a pale vacuolated appearance and showed periodic-acid-Schiff (PAS) and mucicarmine positive mucin. The diagnosis of bilateral Krukenberg tumor was made. As the diagnosis of Krukenberg tumor was made, mammography, barium enema, and endoscopic exploration of the digestive system of the patient were performed to find any primary tumor, but none was revealed. Also carcinoembryonic antigen (CEA) and CA19-9 levels were normal.

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FIG. 1.

Bilateral Krukenberg tumor of the ovary.

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FIG. 2.

Microscopic examination of the sections from ovaries showing mucin-laden signet ring cells, within a cellular ovarian stroma.

Results

The patient is well and without any recurrence at 18 month follow- up.

Discussion

Krukenberg tumor is a rare metastatic signet ring-cell adenocarcinoma of the ovary, accounting for 1%–2% of all ovarian tumors. Common presenting symptoms are abdominal pain and distension. The remaining patients have nonspecific gastrointestinal symptoms or are asymptomatic. In addition, Krukenberg tumor is reportedly associated with virilization resulting from hormone production by ovarian stroma. Ascites are present in 50% of the cases, and usually reveal malignant cells. ¹

There are two main differential diagnoses of ovarian tumors with signet ring cells containing mucin. These are primary mucinous carcinoma and mucinous carcinoid tumors. Primary mucinous tumors of the ovary can contain cells with signet ring appearance at least focally. However, these tumors tend to be more commonly unilateral with a complex papillary pattern. Mucinous carcinoid tumors (either primary or metastatic, most commonly from the appendix) enter the differential diagnosis in this group by having cells that may assume signet ring appearance and resemble Krukenberg tumor cells. Although mucinous carcinoid cells stain with mucin stains similar to Krukenberg tumor cells, immunostains for chromogranin and synaptophysin are usually positive and can easily confirm the diagnosis in favor of mucinous carcinoid.^1,3 Diagnosis of Krukenberg tumor with unknown primary warrants careful investigation, mainly of the digestive tract and other potential sites.

A history of a prior carcinoma of the stomach or any other organ can be obtained in only 20%–30% of the cases. ⁴ In many cases, the primary tumor is very small and can escape detection. In such a situation, diagnosis of Krukenberg tumor warrants careful radiographic and endoscopic exploration of the digestive system in an attempt to detect the primary carcinoma. In the present case, meticulous radiographic and endoscopic investigation failed to detect any primary carcinoma.

Novak and Woodruff  ⁵ have defined the criteria to qualify a Krukenberg tumor as primary tumor of the ovary (primary Krukenberg tumor). This includes:

1. Complete postmortem examination if the patient was dead at the time of the case report. Absence of primary tumor in any organ except the ovary should be proved by a detailed autopsy study.

Conclusions

The prognosis of Krukenberg tumor is poor, and no curative treatment is currently available. ⁷ Distinction is of imminent importance, as classification of Krukenberg tumor as a primary ovarian tumor may lead to suboptimal treatment of the patient.