Poorly differentiated mesenteric carcinoma of unknown primary site detected by abscess formation: case report

Abstract

Background: Carcinoma of unknown primary site (CUP) is said to account for approximately 3 to 5% of all carcinomas. However, an isolated lesion in the abdominal cavity is rare, and there are no reports describing associated abscess formation.

Case presentation: A 76-year-old woman had consulted a previous physician complaining of fever and right lower quadrant abdominal pain. Enhanced computed tomography (CT) showed an abscess formation around the cecum. She was treated conservatively with antibiotics, but the symptoms relapsed and she consulted our hospital. Enhanced CT showed a persistent abscess, a tumorous lesion in the mesentery and right hydronephrosis. Because malignancy could not be ruled out, surgical treatment was selected. At laparotomy, encapsulated abscesses were found on the mesenteric side and outside of the ileocecal region. When we raised the ileocecal region, a tumor was found to be fixed to the right ureter, and there was leakage of white, solid tumor content. This tumor content was submitted to intraoperative frozen section diagnosis which revealed a carcinoma. Ileocecal resection with D3 lymph node dissection and retroperitoneal tumor resection was thus performed. There were no abnormal findings in the uterus and adnexa, nor any evidence of peritoneal dissemination. We regarded this case as an incomplete resection and chemotherapy with paclitaxel and carboplatin was administered. The patient has remained alive and disease-free for almost one year since the primary operation.

Conclusion: We described a case with mesenteric CUP discovered during surgery for an intra-abdominal abscess. It is necessary to pay attention to treatment-resistant intraperitoneal abscesses as they may accompany a tumor.

Figure 1

Re-examination by enhanced computed tomography (CT) scan. The CT scan shows right hydronephrosis (a), a tumorous lesion in the mesentery (b), and persistent encapsulated abscesses on the mesenteric side (c) and on the outside (d) of the ileocecal region.

Figure 2

Intraoperative findings. Encapsulated abscesses can be seen on the mesenteric side (a) and outside of the ileocecal region (b). When we raised the ileocecal region, a tumor was found to be fixed to the right ureter (c). A ureteral stent was inserted into the right ureter; the tumor was then separated and removed from the ureter (d).

Figure 3

Macroscopic findings of the tumor and ileocecal lesion. No changes involving the mucosal surface of the cecum or the terminal ileum were detected.

Figure 4

Histological and immunohistochemical findings of the tumor. Hematoxylin-eosin (HE) staining reveals poorly differentiated carcinoma (a). Alcian blue (AB) staining showed moderate production of mucin accompanied by a partial ductal structure (b). Immunohistochemistry was partially positive for CK34βE12 (about 20% of tumor) (c), positive for AE1/AE3 (d), negative for CDX2 (e), and negative for TTF-1 (f).