Differentiation of primary ovarian tumours from metastatic colorectal carcinoma

Epidemiology

About 7% of all ovarian tumours are metastatic, predominantly from the gastrointestinal tract. Conversely, about 3.4% of women with colorectal carcinoma develop ovarian metastases2. In a few cases, the ovarian mass is the presenting feature.

Histopathology

The ovarian metastases from colorectal carcinomas resemble endometrioid carcinoma and the differentiation of primary ovarian endometrioid and mucinous carcinomas from colorectal metastases is problematic. Although the predominant pattern is that of large glands, there may be a small glandular or papillary architecture. Some cases show a mucinous pattern and goblet cells may be apparent. Deceptively, the mucinous component may appear of borderline malignancy or even focally appear benign: these foci do not prove that the tumour is an ovarian primary2. Dirty necrosis is suggested of a metastasis from colorectum. Metastases from the endocervix usually mimic endometrioid or mucinous tumours of gastrointestinal type, nor endocervical-like/seromucinous type3.

	Primary ovarian mucinous tumours	Mucinous tumours metastatic to ovary
	usually large (>15 cm)	often small (<10 cm)
	unilateral, multicystic with a smooth capsule	bilateral, forming nodules with surface disease
	usually no extra-ovarian disease	there is extra-ovarian disease
	a borderline component is present	usually absent, but may be simulated
	growth is confluent, glandular and expansive	growth is infiltrative

Immunohistochemistry

While cytokeratins may be informative, up to 70% of primary ovarian mucinous carcinomas express cytokeratin 20 and about 10% of colorectal adenocarcinomas express cytokeratin 7.

	Primary ovarian adenocarcinoma		Metastatic colorectal carcinoma
	focal(11-40% of cells positive)	diffuse(>40% of cells positive)	focal(11-40% of cells positive)	diffuse(>40% of cells positive)
CK7	usually positive		5/302
CK20	usually negative (except in mucinous tumours)			29/292
CDX-2	6/231	5/231	1/221	21/221, 6/62
Villin				4/42
CEA				6/72
Inhibin				0/12
P504S	1/231	0/231	2/221	7/221
b-catenin (nuclear)	3/231	1/231	5/221	8/221
positive for at least two of the markers CDX-2, P504S and b-catenin		3/231		20/221
positive for all three of the markers CDX-2, P504S and b-catenin		0/231		7/221

Where the differential is between an ovarian mucinous primary and metastatic colorectal tumour, diffuse expression of CK7 combined with focal CK20 positivity favours an ovarian primary while focal expression of CK7 combined with diffuse positivity for CK20 favours a colorectal primary3.

Negativity for CDX-2 excludes a colorectal primary. Positivity for two, preferably all three, of the markers CDX-2, P504S and b-catenin is diagnostic of a colorectal primary.

		Oestrogen receptor	Progesterone receptor
Primary ovarian tumours	atypical proliferative mucinous, gastrointestinal type	0/30	0/30
	atypical proliferative mucinous, seromucinous type	11/11	7/11
	invasive mucinous carcinoma of usual type	0/11	0/11
Metastatic mucinous carcinoma	gastric	0/4	0/4
	appendiceal	0/4	0/4
	colorectal	0/24	0/24
	pancreatic	0/13	0/13
	gallbladder/biliary tract	0/4	0/4
	endocervical	3/8	0/8
	unknown	0/15	0/15

Hormone receptor expression is of no value in distinguishing atypical proliferative (borderline) mucinous tumours of gastrointestinal type and primary ovarian invasive mucinous carcinomas of usual type from the majority of mucinous carcinomas metastatic to the ovary3.

References

1 Logani S, Oliva E, Arnell PM, et al. Use of novel immunohistochemical markers expressed in colonic adenocarcinoma to distinguish primary ovarian tumors from metastatic colorectal carcinoma. Mod Pathol 2005; 18:19-25

2 Lewis MR, Deavers MT, Silva EG, et al. Ovarian involvement by metastatic colorectal adenocarcinoma: still a diagnostic challenge. Am J Surg Pathol 2006; 30:177-84

3 Vang R, Gown AM, Barry TS, et al. Immunohistochemistry for estrogen and progesterone receptors in the distinction of primary and metastatic mucinous tumors in the ovary: an analysis of 124 cases. Mod Pathol 2006; 19:97-105

This page last revised 17.8.2006.