Prevention of nickel-induced allergic contact reactions with pentoxifylline

Pentoxifylline in dermatology

BACKGROUND

Pentoxifylline was initially marketed for use in patients with intermittent claudication due to chronic occlusive arterial disease of the extremities but has since been shown to have several off-label uses in dermatology.

AIMS

The aim of this review is to increase awareness of the several applications of pentoxifylline in the field of dermatology.

METHODS

A comprehensive PubMed search was conducted in May 2022 using the following phrases "dermatology" AND "pentoxifylline." Our search period spanned 34 years from 1988 to 2022. All available literature was reviewed. Reference lists of identified articles were included. Studies were excluded if they were not in English and if the study was out of scope. Eighty-one articles were included in this review.

RESULTS

Pentoxifylline has been used to treat various dermatological conditions including peripheral vascular disease, vasculitis and vasculopathies, chilblains, pigmented purpuric dermatosis, granuloma annulare, necrobiosis, keloids, lichen sclerosis et atrophicus, scars, radiation-induced fibrosis, vitiligo, alopecia areata, leishmaniasis, and leprosy.

CONCLUSIONS

Pentoxifylline's use in dermatology is growing. However, there are limited larger studies and randomized control trials on the use of pentoxifylline in dermatology and more investigation is needed to evaluate its use for many dermatologic conditions. Pentoxifylline's unique mechanism of action as well as its good tolerability, cost-effectiveness, and minimal drug interactions make it a convenient primary or adjunctive option in many dermatological conditions.

Equine allergy therapy: update on the treatment of environmental, insect bite hypersensitivity, and food allergies

Allergies are common in horses. It is important to identify and correct as many factors as possible to control pruritus and make the patient comfortable. Culicoides hypersensitivity is a common component in allergic horses. The main treatment continues to be rigorous fly control and avoidance of insect bites. Environmental allergies are best addressed by early identification of the offending allergens and formulation of allergen-specific immunotherapy to decrease the need for rescue medications. Food allergy is best managed with food avoidance. Urticaria is one of the manifestations of allergic disease wherein detection of the triggering cause is essential for management.

Nickel-elicited systemic contact dermatitis

20 patients with systemic contact dermatitis due to nickel are described. Of these patients, 15 were female and 5 were male. Their mean age was 24.8 years (16-51 years). All had experienced contact dermatitis in the umbilical area due to continual contact with metal belt-buckles or buttons. Then, with long- or short-term aggravation of such periumbilical dermatitis, commonly in summer, lesions spread to other sites such as the side of the neck, the flexures of the extremities, etc. All patients showed a positive patch test to nickel sulphate (2.5% in petrolatum) and the dimethylglyoxime test demonstrated the presence of free nickel on metal buttons or belt-buckles. Punch biopsies performed in 7 patients showed subacute dermatitis. After avoidance of continual exposure to objects containing nickel and foods rich in nickel, as well as treatment with oral antihistamines and topical corticosteroids, all patients improved or cleared. It has been reported that nickel can cause systemic contact dermatitis by some internal systemic route, such as oral intake, transfusion, inhalation, implantation of metal medical devices, etc. In our patients, we found that continual local skin contact could also elicit systemic contact dermatitis.

Major histocompatibility locus genetic markers of beryllium sensitization and disease

Hypersensitivity to beryllium (Be) is found in 1-16% of exposed workers undergoing immunological screening for beryllium disease using the beryllium lymphocyte proliferation test (BeLPT). However, only approximately 50% of BeLPT-positive workers present with lung granulomas (i.e. berylliosis). As berylliosis is associated with the human leukocyte antigen (HLA)-DP supratypic marker DPGlu69, the authors asked whether this marker is differentially associated with disease presentation. A population of 639 workers from a beryllium factory undergoing BeLPT screening was evaluated in a nested case-control study for the prevalence of HLA-DPGlu69, the HLA-DPB1, HLA-DQ and HLA-DR alleles and of the biallelic tumour necrosis factor (TNF)-alpha polymorphism TNF-alpha-308 in 23 individuals presenting as "sensitized" (i.e. BeLPT-positive without lung granulomas) and in 22 presenting as "diseased" (i.e. BeLPT-positive with granulomas in the lung biopsy). The HLA-DPGlu69 marker was associated with "disease" (odds ratio (OR) 3.7, p=0.016, 95% confidence interval (CI) 1.4-10.0), whilst the high TNF-alpha production-related TNF-alpha-308*2 marker was associated with both a positive BeLPT (OR 7.8, corrected p<0.0001, 95% CI 3.2-19.1) with no difference between "sensitization" and "disease". Furthermore, the HLA-DRArg74 marker was associated with "sensitization" without disease (OR 3.96, p=0.005, 95%, CI 1.5-10.1). The data indicate that tumour necrosis factor-alpha, human leukocyte antigen-DR and human leukocyte antigen-DP markers play different roles in beryllium sensitization and granuloma formation in beryllium-exposed workers.