Nummular dermatitis L30.0

Polyetiologic clinical picture. The disease is generally defined as a therapy-resistant, disseminated, usually chronic or chronic recurrent, pruritic eczematous dermatitis with exudative, circular or oval (nummular), scaly or crusty, often marginal plaques.

Patients with this clinical picture not infrequently show an atopic or psoriatic diathesis or a combination of both, are sometimes contact sensitized or show features of a bacterial or mycotic infection (older term: microbial eczema) of the skin.

Nummular dermatitis is also frequently observed as an accompanying phenomenon of venous stasis dermatitis.

Not uncommon, the data on prevalence varies considerably: between 0.1 and 9.1%.

Overall unclear, usually polyetiological. Various causes are discussed, in particular:

• Superimposed contact allergy
• Atopic dermatitis (intrinsic form of atopic dermatitis)
• Psoriatic diathesis
• Chronic microbial colonization of the skin (esp. Staphylococcus aureus)
• Focal lesions(?)
• In adults association with chronic venous insufficiency.

Two manifestation summits are described:

• The nummular as a special clinical manifestation form of atopic eczema in infancy and childhood.
• The (therapy-resistant) nummular eczema in adulthood (usually occurring after the 50th year of life). In adults, men are more frequently affected than women.

Predilection sites mainly lower leg, less frequently thigh, upper back, upper extremity, possibly also on hands (back of the hand).

Initially usually small, 1-3cm in size, reddish-brownish, itchy, red scaly or crusty papules, papulo vesicles or plaques. Gradual size growth to sharply or blurredly defined, 1.0-6.0 cm large, red coin-like ("nummular eczema") plaques with yellowish crusts or scaly crusts. A lichenification of the lesions occurs if the plaques persist for a longer period of time. No lump formation.

Often marginal progression and central regression within the individual lesions.

No mucosal involvement.

The histological picture is not specific for "nummular dermatitis". Usually an acanthotic widened epidermis with orthohyperkeratosis and focal parahyperkeratosis is found. Edema of varying severity in the papillary dermis. Bulky, perivascularly oriented, but also diffuse predominantly lymphocytic infiltrate with interspersed neutrophilic leukocytes. Focal epidermotropy with spongiotic epithelial reaction.

Histological: contact dermatitis; atopic eczema; tinea (detection in PAS stain)

Clinical signs: Allergic contact dermatitis; psoriasis vulgaris; tinea corporis; microbial superimposed atopic eczema.

Clarification and remediation of triggering factors. If nummular dermatitis can be assigned to an underlying disease, it requires the corresponding specific treatment.

Acute relapse: Antiseptic and antiphlogistic treatment with Clioquinol R050, moist compresses with polihexanide solution(e.g. Serasept, Prontoderm, Prontosan), quinolinol solution(e.g. Chinosol 1:1000), R042 or potassium permanganate (light pink) in alternation with topical glucocorticoids like 0.1% triamcinolone cream(Triamgalen cream, R259 ), 0.25% prednicarbate (e.g. Dermatop cream). Avoid oily bases as these usually lead to a worsening of the skin condition, therefore they are used for the treatment of hydrophilic creams.

After the exudative note has subsided: oil baths (e.g. Balneum® Hermal® oil bath). Skin care e.g. with Ungt. emulsif. aq., Linola® milk, Eucerin® lotio or Sebamed® lotio. Typically, the entire skin is susceptible to irritant noxae (moist contacts etc.), therefore skin protection (hands) is urgently required in both occupational and non-occupational areas.

The entity of the clinical picture remains controversial.

1. Adachi A et al (2000) Mercury-induced nummular dermatitis. J Am Acad Dermatol 43: 383-385.
2. Aoyama H et al (1999) Nummular eczema: An addition of senile xerosis and unique cutaneous reactivities to environmental aeroallergens. Dermatology 199: 135-139
3. Bonamonte D et al (2012) Nummular eczema and contact allergy: a retrospective study. Dermatitis 23:153-157
4. Devergie MGA (1857) L'eczéma nummulaire et le pityriasis rubra pilaire. In: Traité pratique des maladies de la peau. Victor Masson (Paris)
5. Gläser R (2015) What do I do about so-called microbial eczema? JDDG 13 (Suppl1) 45
6. Kim WJ et al.(2013) Features of Staphylococcus aureus colonization in patients with nummular eczema. Br J Dermatol 168:658-660
7. Roberts H et al (2010) Methotrexate is a safe and effective treatment for paediatric discoid (nummular) eczema: a case series of 25 children. Australas J Dermatol 51:128-130
8. Röckl H (1972) The nummular and the microbial eczema. Dermatologist 23: 326-330
9. Tanaka T et al (2009) Dental infection associated with nummular eczema as an overlooked focal infection. J Dermatol 36:462-465