Mercury-induced nummular dermatitis

Nummular Eczema: An Updated Review

Background:

Nummular eczema may mimic diseases that present with annular configuration and the differential diagnosis is broad.

Objective:

This article aimed to provide an update on the evaluation, diagnosis, and treatment of nummular eczema.

Methods:

A PubMed search was performed in using the key terms “nummular eczema”, “discoid eczema”, OR “nummular dermatitis”. The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature. The information retrieved from the above search was used in the compilation of the present article. Patents were searched using the key terms “nummular eczema”, “discoid eczema”, OR “nummular dermatitis” in www.google.com/patents and www.freepatentsonline.com.

Results:

Nummular eczema is characterized by sharply defined, oval or coin-shaped, erythematous, eczematous plaques. Typically, the size of the lesion varies from 1 to 10cm in diameter. The lesions are usually multiple and symmetrically distributed. Sites of predilection include the lower limbs followed by the upper limbs. The lesions are usually intensely pruritic. The diagnosis is mainly clinical based on the characteristic round to oval erythematous plaques in a patient with diffusely dry skin. Nummular eczema should be distinguished from other annular lesions. Dermoscopy can reveal additional features that can be valuable for correct diagnosis. Biopsy or laboratory tests are generally not necessary. However, a potassium hydroxide wet-mount examination of skin scrapings should be performed if tinea corporis is suspected. Because contact allergy is common with nummular eczema, patch testing should be considered in patients with chronic, recalcitrant nummular eczema. Avoidance of precipitating factors, optimal skin care, and high or ultra-high potency topical corticosteroids are the mainstay of therapy. Recent patents related to the management of nummular eczema are also discussed.

Conclusion:

With proper treatment, nummular eczema can be cleared over a few weeks, although the course can be chronic and characterized by relapses and remissions. Moisturizing of the skin and avoidance of identifiable exacerbating factors, such as hot water baths and harsh soaps may reduce the frequency of recurrence. Diseases that present with annular lesions may mimic nummular eczema and the differential diagnosis is broad. As such, physicians must be familiar with this condition so that an accurate diagnosis can be made, and appropriate treatment initiated.

Severe dermatitis might be caused by a cross-reaction between nickel and palladium and dental amalgam resolved following removal of dental restorations

This report demonstrates a case of atopic dermatitis that was unresponsive to topical steroid therapy. This clinical report highlights the fact that metals used in dental treatment, such as mercury, as well as cross‐reactions between nickel and palladium, may cause systemic hypersensitivity or toxicity.

Mast cell histamine-mediated transient inflammation following exposure to nickel promotes nickel allergy in mice

We previously reported that allergic responses to nickel (Ni) were minimal in mice deficient in the histamine-forming enzyme histidine decarboxylase (HDC-KO), suggesting an involvement of histamine in allergic responses to Ni. However, it remains unclear how histamine is involved in the process of Ni allergy. Here, we examined the role of histamine in Ni allergy using a murine model previously established by us. Mice were sensitized to Ni by intraperitoneal injection of a NiCl2 -lipopolysaccharide (LPS) mixture. Ten days later, allergic inflammation was elicited by challenging ear-pinnas intradermally with NiCl2 . Then, ear-swelling was measured. Pyrilamine (histamine H1-receptor antagonist) or cromoglicate (mast cell stabilizer) was intravenously injected 1 h before the sensitization or the challenge. In cell-transfer experiments, spleen cells from Ni-sensitized donor mice were intravenously transferred into non-sensitized recipient mice. In both sensitized and non-sensitized mice, 1 mm or more NiCl2 (injected into ear-pinnas) induced transient non-allergic inflammation (Ni-TI) with accompanying mast cell degranulation. LPS did not affect the magnitude of this Ni-TI. Pyrilamine and cromoglicate reduced either the Ni-TI or the ensuing allergic inflammation when administered before Ni-TI (at either the sensitization or elicitation step), but not if administered when the Ni-TI had subsided. Experiments on HDC-KO and H1-receptor-KO mice, and also cell-transfer experiments using these mice, demonstrated histamine's involvement in both the sensitization and elicitation steps. These results suggest that mast cell histamine-mediated Ni-TI promotes subsequent allergic inflammatory responses to Ni, raising the possibility that control of Ni-TI by drugs may be effective at preventing or reducing Ni allergy.

Nummular eczema in children and adults: clinical picture and differential therapy approaches

The article deals with present-day ideas on pathogenesis and treatment of Nummular eczema, differences between clinical I picture of the disease with children and adults.

Dermatitis caused by metal allergy after coil embolization for unruptured cerebral aneurysm

We report a rare case of metal-induced dermatitis after coil embolization for cerebral aneurysm. A 51-year-old woman experienced a rash around the lips and neck 3 weeks after coil embolization. Judging from the clinical course and results of several patch tests, platinum coils were considered to have induced the dermatitis. Symptoms were relieved with administration of oral steroids. This represents the first report of metal-induced dermatitis after neuroendovascular treatment. The possibility of metal allergy was difficult to suspect preoperatively. However, early evaluation and referral are important when skin symptoms are observed postoperatively.

Dermatitis caused by metal allergy after coil embolization for unruptured cerebral aneurysm

We report a rare case of metal-induced dermatitis after coil embolization for cerebral aneurysm. A 51-year-old woman experienced a rash around the lips and neck 3 weeks after coil embolization. Judging from the clinical course and results of several patch tests, platinum coils were considered to have induced the dermatitis. Symptoms were relieved with administration of oral steroids. This represents the first report of metal-induced dermatitis after neuroendovascular treatment. The possibility of metal allergy was difficult to suspect preoperatively. However, early evaluation and referral are important when skin symptoms are observed postoperatively.

Gingivo-mucosal and cutaneous reactions to amalgam fillings

BACKGROUND

A number of reports exist on the side effects of materials used to restore teeth. Most of the cases involve local allergy reactions, but also skin lesions are described. Few cases are described where both local effects on the mucosa and skin lesions distant to the oral cavity are caused by amalgam.

RESULT

The case presented indicates that the release of mercury from amalgam fillings is able to induce hypersensitivity reactions resulting in soft-tissue changes in the gingiva, buccal mucosa, tongue and on the skin of the back of the hands.

Systemically induced allergic exanthem from mercury

Cutaneous reactions to mercury can manifest themselves in different forms. Apart from contact dermatitis, flare-up reactions, disseminated exanthem as well as skin symptoms in previously unaffected skin are known. Regarding systemic allergen application, 2 separate clinical patterns, namely acute generalized exanthematous pustulosis (AGEP) and symmetric flexural exanthem 'baboon syndrome' have been described. Systemic allergic reactions to mercury are most commonly provoked by the inhalation of metallic mercury vapours from a broken thermometer, often after previous sensitization to mercury compounds, e.g. Mercurochrome. Patch testing with mercurials yields positive reactions in approximately 80% of patients. We report 3 patients, 2 with flexural exanthem, and 1 presenting with AGEP, respectively. Positive patch tests to mercury derivatives could be demonstrated in all of them. Furthermore, non-toxic serum mercury levels were detected in 2 of the patients. The present review provides a survey of the literature on systemic allergic exanthem to mercury. However, plausible explanations for the distribution pattern of the skin manifestations in AGEP and flexural exanthem are still lacking.