268 Unilateral Krukenberg Tumors from Colorectal Adenocarcinoma: Diagnostic Challenges and Immunohistochemical Differentiation

Introduction/Objective Krukenberg tumors (KT) are metastatic ovarian malignancies most commonly originating from gastric adenocarcinoma and less frequently from colorectal adenocarcinoma. These tumors are typically associated with bilateral ovarian involvement. However, this case series describes five rare examples of unilateral KT arising from colorectal adenocarcinoma. The unique presentation of unilateral ovarian involvement creates diagnostic challenges and can involve different metastatic mechanisms. This review explores diagnostic methods, possible metastatic pathways, and clinical significance. Methods/Case Report A retrospective search in SoftPath, conducted from January 10, 2015 to January 10, 2025 at Westchester Medical Center, identified five cases of metastatic ovarian tumors developing from colorectal adenocarcinoma. Clinically, all patients presented with abdominal discomfort and weight loss. Imaging revealed a unilateral ovarian mass, while colonoscopy detected an obstructive colorectal lesion. Unilateral oophorectomy and colectomy were performed to confirm the diagnosis and treat the underlying pathology. Results Histopathological examination of the colon and ovarian samples in each case revealed moderately differentiated adenocarcinoma with lymphovascular invasion. Immunohistochemistry for both tissue types showed positive staining for CDX2, SATB2, and CK20, confirming a colorectal origin, as well as negative staining for PAX8 and CK7, ruling out a primary ovarian malignancy. Conclusion This case series highlights the importance of recognizing colorectal adenocarcinoma as a source of KT, particularly in unilateral presentations. Given the presence of lymphovascular invasion in all five cases, lymphatic spread is a possible metastatic mechanism. Comprehensive diagnostic strategies, including immunohistochemistry, are essential for differentiating metastasis from primary ovarian malignancies and guiding effective treatment.