A Patch Test-Positive Titanium Hypersensitivity Reaction.

A 31-year-old woman developed pruritic scaly plaques on her lateral and medial ankle 8 months after open reduction and internal fixation with titanium hardware for repair of right ankle fracture. The rash was confined to the area over and surrounding the incision site scars (Fig. 1A). Deep infection was initially suspected by orthopedic surgery, and she was treated with cephalexin with minimal improvement. The hardware was removed 9 months after implantation owing to pain and continued concern for infection. The explanted hardware grew rare coagulase negative Staphylococcus, and she was given clindamycin. Tissue biopsy at the time of hardware removal showed psoriasiform spongiotic mixed dermatitis with eosinophils (Fig. 1B), consistent with allergic contact dermatitis or atopic dermatitis. The incision sites healed after the hardware was removed, but the pruritic plaques around the incision sites did not resolve. The patient was referred to the Contact Clinic at Oregon Health & Science University out of concern for allergic contact dermatitis. The patient was patch tested to 58 allergens including numerous metals such as nickel, chrome, cobalt, titanium, silver, and copper, acrylates, and antibiotics including vancomycin, gentamycin, neomycin, and bacitracin. She had 2 patch test readings at 48 hours and 7 days and was noted to have a 1+ positive result of patch test to titanium oxalate at both readings (Fig. 1C). All other test results were reported negative including titanium dioxide, a common component in sunscreens. An Unna boot dressing with clobetasol ointment was applied to the rash and left on for 7 days during patch testing. Unna dressings with zinc-impregnated gauze over an emollient or steroid ointment have been shown to heal acute surgical wounds. This treatment resulted in clearing of rash (Fig. 1D). Antibiotics were discontinued, and she remained clear at follow-up 4 months later. Titanium is used in implanted surgical devices, in particular, for patients who are thought to be metal-sensitive. Type 4 delayed hypersensitivity reactions to titanium are exceedingly rare, and there are only 3 case reports in the literature of suspected titanium hypersensitivity from orthopedic implants. In addition to low prevalence, diagnosing titanium hypersensitivity is further complicated by lack of a widely accepted screening tool. Positive patch test results to titanium are uncommon owing to lack of penetration of titanium salts through the epidermis. This is supported by the 3 previous reported cases of contact dermatitis to titanium from an orthopedic device, which were all patch test negative for titanium. Our patient’s positive result of patch test for titanium suggests that patch testing to titanium may be more beneficial than originally recommended. Despite positive or negative patch test results, the definitive treatment for suspected titanium hypersensitivity consists of removal of the device. Although hardware removal led to decreased pain, her rash did not resolve until the Unna boot dressing was applied and left in place for 1 week. This treatment provided a greasy and soothing barrier, interrupted the itch-scratch cycle, and decreased the swelling of the ankle. Figure 1. A, Right lower leg at time of presentation showing erythematous scaly plaque at the site of surgical excision. B, Skin biopsy from hardware explant showing psoriasiform spongiotic mixed dermatitis with eosinophils. C, 1+ positive result of patch test to titanium oxalate 5% in petrolatum. D, Right lower leg after hardware removal and 1 week of treatment with clobetasol. PEARLS & ZEBRAS