The etiology of prurigo pigmentosa remains unknown. Endogenous and exogenous factors have been proposed. Potential endogenous factors include ketosis (such as from dieting or fasting), diabetes mellitus, and pregnancy. Exogenous factors may include friction (eg, from clothing) and contact allergic reactions (eg, to chrome or nickel, trichlorophenol, or para-amino compounds). Associations with other conditions have been reported, including adult-onset Still disease, Sjögren syndrome, atopy, and Helicobacter pylori infection.
The exact pathogenesis of prurigo pigmentosa is not clear. Neutrophil-mediated inflammation induced by ketosis has been suggested.
L28.2 – Other prurigo
238589009 – Prurigo pigmentosa
Differential Diagnosis & Pitfalls
- Papular urticaria
- Contact dermatitis
- Asteatotic eczema
- Papular pityriasis rosea
- Dermatitis herpetiformis
- Linear IgA dermatosis
- Pityriasis lichenoides et varioliformis acuta (PLEVA)