Contact Dermatitis to Metal: Case Study Dermatitis

Contact dermatitis on the hands can be caused by a number of distinct mechanisms (Usatine & Riojas, 2010). The type most amenable to treatment is dermatitis caused by environmental irritants. Other possible causes include allergic and atopic dermatitis, each arising from different mechanisms. The patient under consideration here has been diagnosed with contact dermatitis due to metal exposure and is concerned about a possible link between the eczema and rhinitis. This report will examine the pathophysiology of contact dermatitis and whether there could be any relationship between the patient's dermatitis and rhinitis.

Irritant Contact Dermatitis

Irritant contact dermatitis is caused by exposing the skin to harmful substances (Usatine & Riojas, 2010). A wound or injury can compromise the ability of the skin to maintain an effective barrier against noxious substances, resulting in skin trauma. A single or chronic exposure can lead to local inflammation of the skin and produce a characteristic pattern of thick, scaly lesions on the hands (Alavi, Skotnicki, Sussman, & Sibbald, 2012). Treatment and management is fairly straightforward and involves cleansing the skin, bandaging any wounds or injuries, and preventing future exposures either through avoiding the substance or the use of personal protective gear. Irritant contact dermatitis can lead to the development of allergic contact dermatitis.

Allergic Contact Dermatitis

Allergic contact dermatitis (ACD) results when the immune system has inappropriately reacted to an otherwise benign substance as if it was a harmful agent (Usatine & Riojas, 2010). One of the most important functions of the skin is to distinguish between useful or commensal microbes and those that could potentially harm us (McFadden, Puangpet, Basketter, Dearman, & Kimber, 2013). The skin would not be able to perform...

The immune system also plays a critical role in wound repair, including the growth of new tissue. This system has gone astray when ACD has developed.
Some of the most common allergens that cause contact dermatitis are poison ivy and nickel (Usatine & Riojas, 2010). Statistically, the patient who is the subject of the case study under consideration here would most likely have ACD to nickel, although other metals have been known to cause ACD. A recent meta-analysis of skin patch tests revealed the most common allergen identified was nickel (14.7%), followed by thimerosol (5.0%), cobalt (4.8%), and fragrance (3.4%). However, in most people these substances do not illicit an immune reaction, which begs the question of why ACD occurs.

There are two mechanisms believed to lead to the development of ACD and these include immune activation during wound repair and/or a non-commensal microbe infection (McFadden, Puangpet, Basketter, Dearman, & Kimber, 2013). Regardless of how the metal came into contact with the patient's immune system the sensitization results in the metal being 'seen' as dangerous. Immune tolerance to the metal is therefore lost, theoretically through a process of covalent binding to skin proteins; however exposure to the metal alone is usually insufficient to trigger an immune response. What is needed is a 'danger' or 'pathogen' signal being presented to the immune system at the same time it exposed to the metal.

The danger signal consists of extracellular matrix proteins released when skin trauma occurs (McFadden, Puangpet, Basketter, Dearman, & Kimber, 2013). These proteins are called danger-associated molecular patterns (DAMPs) and include fibronectin, hyaluronan, cathelicidin, and heparin sulfate. Non-commensal microbes also produce…