Prurigo pigmentosa L28.2

Rare inflammatory dermatosis of unexplained aetiology, predominantly observed in Japan, but apparently also occurring in other ethnic groups, with chronically recurrent inflammatory dermatosis.

According to B Beutler et al (2015), PP can be divided into 5 groups:

• Prurigo pigmentosa, allergy-associated.
• Prurigo pigmentosa, disease-associated
• Prurigo pigmentosa, diet-associated
• Prurigo pigmentosa, pregnancy-associated
• Prurigo pigmentosa, associated with other observations.

Predominantly described in Japan and Southeast Asia (e.g. Korea); very rarely occurring in the Caucasian population. As of March 2021, 259 cases have been described outside Japan, including 21 in Europe.

Unknown. Associations with the occurrence of diabetes mellitus, nutritional disorders (anorexia nervosa) or malnutrition, overall ketoacidotic metabolic state after fasting are discussed. Individual cases with adult Still's disease, Sjögren's syndrome, Helicobacter pylori infection and atopic diathesis are described.

Mostly occurring in the 2nd or 3rd decade of life (in a larger study - range: 15-61 years, average 23.7 years). Women are 2-3 times more frequently affected than men. Frequently occurring in spring or summer and occurring in relapses.

Symmetrical distribution pattern; infestation of the back, neck and chest.

Early stage: Acute onset, intensely pruritic, symmetrical reddish, urticarial papules or plaques. In the full-blown stage: papulo-vesicles, vesicles and excoriations. Mostly reticular arrangement. In late stage- healing under hyperpigmentation in reticular arrangement.

Early stage: Superficial perivascular infiltrates in the sense of neutrophilic dermatitis with epidermotropy.

In the full stage: spongiosis of the epidermis, occasionally with intraepidermal vesiculation. Subepidermal blistering is also possible. Sporadic necrobiotic keratinocytes and neutrophilic epithelial abscesses exist.

In later stages, there is a decrease in neutrophilia; instead, there is an increased occurrence of eosinophilic leukocytes and lymphocytes, melanophages in the papillary dermis. The epidermis shows acanthosis, parakeratosis and hyperpigmentation.

prurigo simplex subacuta

dermatitis herpetiformis

REM syndrome

Papillomatosis confluens et reticularis (described by some authors as an inflammatory variant of this disease)

Good response to DADPS (e.g. dapsone fatol) 25-100 mg/day and sulfamethoxazole 2 g/day p.o.

Alternatively: Minocycline (e.g. Klinomycin) initially 100-200 mg/day p.o. for 3-7 days, then dose reduction to 50-100 mg/day p.o. Continuation of therapy for 2-3 weeks after symptoms have subsided. Under this therapy healings can be achieved (Ebnöther M et al. 2017).

Alternative: In individual cases a good response to isotretinoin (0.3 mg/kg bw) has been reported.

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