Case Diagnosis and Discussion

Diagnosis

Krukenberg tumor.

Discussion

The term Krukenberg tumor is typically indicative of a metastatic gastric adenocarcinoma with signet ring morphology that involves the ovaries through lymphovascular spread. In the western population it accounts for 1-2% of ovarian tumors, though this rate is considerably higher (up to 15-20%) in countries with higher rates of gastric adenocarcinomas, such as Japan. It is controversial as to whether primary Krukenberg tumors exist due to the observation that gastric adenocarcinomas often remain silent prior to metastatic spread to the ovaries. Krukenberg tumors have a very selective pattern of metastasis to the ovaries, which is believed to arise through retrograde lymphatic spread and occur bilaterally in 80% of cases. The average age of diagnosis for this diffuse type of Krukenberg tumor is approximately 45 years old. Prognosis is very poor with a median survival of 14 months (1).

Krukenberg tumors typically involve both ovaries and demonstrate a smooth but lobulated ovarian surface, with ovarian tumors averaging 10 cm in greatest dimension. Microscopic features include classic signet ring cells, characterized by neoplastic cells with a hyperchromatic, eccentric nucleus peripherally displaced by a mucin-laden vacuole. There is typically little mitotic activity. The identification of intracytoplasmic mucin aids in the diagnosis and can be highlighted by mucicarmine, PAS-D or Alcian blue stains. Additionally, tumor cells are immunoreactive to cytokeratins (AE1/AE3) as well as epithelial membrane antigen (1). The tumor may demonstrate cytokeratin 7, cytokeratin 20, and CDX2 positivity.

The differential diagnosis for Krukenberg tumors includes primary mucinous carcinoma of the ovary which can also have signet ring cells. Signet ring cells are rare in these primary mucinous carcinomas and they are more likely to present unilaterally and also exhibit papillary architecture (2). Mucinous carcinoid tumors may also demonstrate tumor cells in a mucinous background, but will stain positively with chromogranin and synaptophysin immunostains (1). 

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References

1.      Al-Agha OM and AD Nicastri. "An In-depth Look at Krukenberg Tumor." Arch Pathol Lab Med 2006; 130: 1725-730.

2.      McCluggage WG and RH Young. “Primary ovarian mucinous tumors with signet ring cells: report of 3 cases with discussion of so-called primary Krukenberg tumor.” Am J Surg Pathol 2008; 32 (9):1373-9.