Clinicopathological features and the value of differential Cytokeratin 7 and 20 expression in resolving diagnostic dilemmas of ovarian involvement by colorectal adenocarcinoma and vice-versa

In cases of complex presentations like an ovarian involvement by a metastatic colorectal adenocarcinoma and vice-versa, certain clinicopathological features are useful. Differential expression of CK 7 and CK20 is vital in resolving these dilemmas. CK20 positivity and CK7 negativity is associated with a colorectal adenocarcinoma. Markers like CEA and CA-125 have an added value.The ovary is a site for a wide range of tumors, both primary and metastatic. Approximately 10–30% of ovarian tumors are metastatic, commonly from the breast, stomach, and the colon [1]. Of these, colorectal metastasis account for approximately 4% [2]. Morphologically, these tumors mimic primary ovarian adenocarcinomas, especially ovarian endometrioid adenocarcinomas. Rarely, colorectum becomes a site for a metastasis from an ovarian adenocarcinoma [3]. Identification of the correct primary tumor in both the described presentations is necessary for an optimal management, including, specific chemotherapy (CT) in advanced stages. Whereas, ovarian adenocarcinomas respond to platinum based CT, cases of colonic adenocarcinomas are candidates for 5-fluorourocil based CT. [4]. The known clinical features favoring a metastatic tumor into the ovary include history of an antecedent malignancy, relatively smaller size of the tumor ~10 cms, solid structure, frequent bilaterality; absence of ascites and elevated serum carcinoembryonic antigen (CEA) levels [1]. Certain morphological features indicative of metastasis from colorectum include 'garland-like' tumor necrosis, segmental destruction of glands and absence of squamous metaplasia, whereas cribriform growth patterns and intraluminal "dirty" necrosis are indicators of endometrioid ovarian adenocarcinomas [5,6]. However, problem exists in sorting out these tumors, including in cases mucinous adenocarcinomas, when there is simultaneous involvement of the ovary and the colorectum at similar (synchronous) or at different (metachronous) times [6,7]. Lately, cy