Histopathological comparison between endofibrosis of the high-performance cyclist and atherosclerosis in the external iliac artery

Introduction

High performance athletes, predominantly professional cyclists, can develop symptomatic arterial flow restriction in one or both legs during exercise. The ischemic symptoms are caused by endofibrosis and/or kinking of the external iliac artery. Because these athletes are young and have no classic risk factors for atherosclerosis, endofibrosis and atherosclerosis are considered different disease entities. We compared histology of endofibrotic lesions from young sportsmen with atherosclerotic lesions of the external iliac artery in elderly individuals.

Methods and Results

Nineteen external iliac endarterectomy specimens from 18 cyclists (age 29 ± 8 years) were compared with 42 external iliac segments from 22 elderly individuals (82 ± 10 years). Ten arteries from elderly individuals revealed an intimal area that was ≥25% of the area encompassed by the internal elastic lamina and were considered atherosclerotic lesions. Stenosis was higher in patients (65% [interquartile range 50-75]) than in controls (11% [7-24]) (P < .0001). The endofibrotic lesions revealed loose connective tissue with moderate to high cellularity. Both in endofibrosis and atherosclerosis, most cells in the lesion were smooth muscle actin positive. In the endofibrosis specimens, loose fibers of collagen were observed, whereas in the atherosclerotic lesions collagen was mostly densely packed. Calcification of the lesion was not observed in endofibrotic lesions, whereas calcium deposition was observed in 80% of atherosclerotic lesions. Lymphocytes were present in 21% of endofibrotic lesions and in 80% of atherosclerotic cases. Macrophages were observed in 16% of endofibrotic lesions and in all atherosclerotic plaques. Luminal thrombosis was observed in one case of endofibrosis.

Conclusion

In the external iliac artery, atherosclerotic lesions and endofibrotic lesions of high performance cyclists have distinct morphologic characteristics. Endofibrosis in the external iliac artery may serve as soil for luminal thrombosis.

Clinical Relevance

Endofibrosis can be a serious clinical problem in high-performance athletes. Because endofibrosis predominantly occurs in sportsmen, most surgeons do not frequently see patients with endofibrosis. The results of the present study show that endofibrosis has distinct histologic characteristics as compared to atherosclerosis. In clinical practice, it is important to recognize patients with endofibrotic lesions, because endofibrosis and atherosclerosis require different diagnostic and therapeutic approaches.