A CCR-AAA is a well-known, extremely rare subtype of AAA that was first reported by Szilagyi et al. in 1961 [1,2,3]. It is characterized by low blood loss and stable hemodynamics, which are due to hemostasis by tissue peripheral to the retroperitoneum when the aortic aneurysm ruptures [4, 5].
The diagnostic criteria for CCR-AAA consist of the following: (1) known AAA; (2) previous pain symptoms; (3) stable condition and normal hematocrit; (4) a CT scan showing a retroperitoneal hematoma; and (5) pathological confirmation of an organized hematoma [1, 2]. Although back pain is common, cases of CCR-AAA present with a wide variety of clinical findings, including cases which are asymptomatic [4,5,6]. The diagnosis of CCR-AAA thus poses a dilemma. Although the present case met the first three aforementioned criteria, we could not obtain conclusive evidence indicating that the neoplastic lesion observed via the CT was a hematoma, nor could we diagnose CCR-AAA to the exclusion of other diseases. Diseases from which CCR-AAA must be distinguished include retroperitoneal tumor and abscess [1, 2]. CT is a useful modality for diagnosing CCR-AAA; it shows a well-defined soft-tissue density mass, inside which there is often no contrast effect, adjacent to the aortic wall [4]. In addition to CT, FDG-PET is also reported to be effective for the definitive diagnosis of CCR-AAA. Although neoplastic and inflamed lesions typically exhibit accumulation of FDG in the lesion, CCR-AAA is characterized by the accumulation of FDG in the margin of the neoplastic lesion alone and by the absence of accumulation in the abdominal aorta. FDG-PET confirmed such criteria in the present case. However, these findings may also be observed in abscesses and in tumors with central necrosis [2]. Moreover, increased accumulation of FDG was also observed in the sigmoid colon, and tumor markers were elevated. We could not therefore rule out the possibility of neoplastic disease. During the course of the disease, we also suspected invasion by the tumor because of the abdominal aortic occlusion. Although tumor invasion into the aorta is relatively rare, invasion into blood vessels by malignancies, such as sarcomas, should be considered [7, 8].
The fact that CCR-AA is a rare condition further confounds diagnosis. Although there have been several reported cases in recent years of CCR-AAA with vertebral invasion, we could find only one reported case of CCR-AAA with abdominal aortic occlusion [4]. In the report by Yokomuro et al., complication of CCR-AAA by infrarenal abdominal aortic occlusion was confirmed. However, abdominal aortic occlusion had already been observed in the initial examination. Nothing was stated concerning a relationship between the aortic occlusion and CCR-AAA [4].
In the present case, the abdominal aorta was confirmed to be patent at the initial examination, and there were no stenotic lesions. However, a detailed examination at 1 month showed that occlusion had occurred in the course of CCR-AAA. Although antiphospholipid syndrome co-occurs in some cases, acute occlusion of the abdominal aorta often occurs due to embolization of intracardiac thrombi associated with atrial fibrillation [9, 10]. The patient in the present case had no history of atrial fibrillation, did not present with intracardiac thrombi, and exhibited co-occurring deep vein thrombosis. We therefore suspected the involvement of antiphospholipid syndrome. However, blood test results ruled out this possibility. Although the occurrence CCR-AAA followed by abdominal aortic occlusion suggests the involvement of both, there are no reports demonstrating a relationship between aortic rupture and aortic occlusion. Consequently, nothing is known about a causal relationship.
A ruptured abdominal aortic aneurysm is typically treated with open repair, although endovascular aneurysm repair has also recently been reported to be effective [11]. On the other hand, CCR-AAA has been treated in all reports with vascular prosthesis implantation or bypass surgery [1, 2, 4,5,6]. As in the present case, endovascular aneurysm repair is difficult to perform in cases with arterial occlusion. Open surgery for diagnosis and treatment is considered suitable for cases in which the possibility of a tumor or infection cannot be ruled out before surgery.