Cannulating tunneled dialysis access in the keloid-prone patient

Keloids are benign overgrowths of scar tissue composed of overproduction of cellular matrix and dermal fibroblasts. As with all genetic diseases, the prevalence of keloids varies between different patient populations, ranging from 0.09% in Great Britain to 16% in the Congo.1 Patients with the genetic predisposition to keloid formation can form large overgrowths following any skin insult.2 In addition to cosmetic concerns and disfigurement, keloids can also be painful.3 Recurrence of keloids is common despite both medical therapy and surgical removal.

Patients on hemodialysis (HD) who are prone to keloid formation present a unique challenge. Multiple studies have shown that the preferred method of access for hemodialysis is via an arteriovenous fistula (AVF).4 This was further promoted by the Fistula First initiative resulting in an increased prevalence of AVF. During cannulation of the AVF, the skin overlying the fistula is traumatized, predisposing this population to keloid formation. Further K/DOQI guidelines suggest rotating the site of the needle placement along the AVF to decrease the incidence of pseudoaneurysms.5, 6 While the K/DOQI guidelines are beneficial to the HD population at large, if we generalize to include this unique population, we place them at risk for extensive scarring and keloid formation.

To our knowledge, management of HD patients prone to keloids has not been addressed in the literature. We present four cases of patients on HD who developed keloids, and how they were managed. In our centers' diverse patient population, the incidence of keloids is about 1 in 200.

As opposed to normal scar formation, which demonstrates collagen bundles oriented in an organized fashion, keloids contain collagen type I and collagen type III fibers haphazardly connected.7 In patients with a genetic predisposition to keloid formation, regulating growth factors, including transforming growth factor, platelet-derived growth factor, and vascular endothelial growth factor, are overexpressed in the fibroblasts present in keloids, suggesting pathological signaling in the normal mechanisms of wound healing.8-10

The differential diagnosis of keloids includes hypertrophic scars. In contrast to keloids, hypertrophic scars, while large, remain confined within the site of the wound, regress with time, and lack the large disorganized collagen bundles typical of keloids. In addition, keloids are often painful with hyperesthesia, features absent in hypertrophic scars.11

Treatment options for keloids include surgical excision, pressure/compression therapy, radiation, and intralesional corticosteroids. All of these options yield suboptimal results and are associated with complications. Surgical excision carries with it a high incidence of recurrence. Radiation therapy is associated with an increased risk of cancer, as well as scar hyperpigmentation. Intralesional corticosteroids lead to a decrease in the size of keloids, but do not eliminate them.6

Keloids present a unique challenge in chronic HD patients. Patients predisposed to keloid formation are routinely instructed to take precautions to avoid skin trauma; however, HD patients require surgical creation of an AVF, regular cannulation of the access for HD, and interval fistuloplasty for maintenance.

We propose an approach of repeated same-site cannulation of the AVF—accessing the AVF through the preexisting keloid. This would result in prevention of new keloid formation, less cosmetic disfigurement, and a decrease in pain with cannulation. Accessing the AVF either with longer needles or by using the buttonhole technique are both possible techniques to achieve same site cannulation through keloids. None of the patients who had same-site cannulation developed pseudoaneurysms. The thickened collagen bundles characteristic of keloids may serve to reinforce vascular integrity and protect against pseudoaneurysm formation.