[682] Carcinoma of Mullerian Origin Presenting as Colorectal Cancer: Histologic and Immunohistochemical Studies of 13 Cases

H Wang, Q Yang, HY Cho, SJ Jung, KR Kim, JY Ro, SS Shen. The University of Texas M.D. Anderson Cancer Center, Houston; Three Gorges University Medical College, Yichang, China; Gachon University Gil Medical Center, Incheon, Korea; Inje University College of Medcine, Busan, Korea; University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea; The Methodis Hospital and Research Institute, Houston

Background: Carcinomas of mullerian origin involving colorectum in women with no history gynecologic malignancies are diagnostically challenging. In this study, we described 13 cases of carcinoma of mullerian origin with clinical presentation mimicking colorectal carcinoma. Salient morphologic features as well as selective immunohistochemical markers that might be useful for differential diagnosis were described.
Design: Thirteen cases of carcinoma of mullerian origin with clinical presentation mimicking colorectal cancer were identified from three large hospitals. None of patients had concurrent or history of gynecologic malignancies 10 years prior to the presentation. H&E slides from each case were reviewed with specific attention to the presence or absence of associated endometriosis. Immunohistochemistry with a panel of markers that may aid in the correct diagnosis were performed.
Results: The average patient age was 63.9 years (range 34-86). All cases except one presented as rectosigmoid or rectovagnal septum mass. The presenting symptoms were rectal bleeding (4/11), rectosigmoid mass (6/11), vaginal mass (1/11), abdominal pain or constipation (2/11). The average size of tumor was 4.2 cm (range 2.4-15.0 cm). Nine of 13 cases had colorectal biopsy and one had vaginal biopsy. The tumor were either moderately differentiated endometrioid (6/11), high grade serous (2/11), mixed serous with endometrioid (2/11), undifferentiated (1/11), or malignant mixed mullerian tumor (2/11). In 8 of 13 cases, endometriosis were identified adjacent or within the tumor. One case had endosalpingiosis. Immunohistochemical stains showed following positive results: CK7(13/13), ER(13/13), PR (10/13), CK20 (0/13), CDX-2(0/13).
Conclusions: Carcinoma of mullerian origin can present as bulky mass in rectosigmoid or rectovaginal septum clinically mimicking primary colorectal cancer. Most of them are of endometrioid or serous types. These results also suggest that endometriosis might be the etiological factor. Identification of benign endometriosis and immunohistochemical stain with a panel of markers (CK7, CK20, CDX2, ER, and PR) is very helpful for the confirmatory diagnosis.
Category: Gastrointestinal

Tuesday, March 10, 2009 11:00 AM

Platform Session: Section C, Tuesday Morning