Prurigo pigmentosa

What is it prurigo pigmentary?

Prurigo pigmentosa is a rare inflammatory skin condition associated with ketosis. It is characterized by a recurrent itchy eruption with netlike hyperpigmentation. Prurigo pigmentosa responds well to tetracycline and has excellent forecast.

Prurigo pigmentosa is also known as Nagashima disease and 'ketogenic rash'.

Who gets prurigo pigmentosa?

Prurigo pigmentosa has been described in people of all ages, sex and ethnic groups. However, it is more common among Asians, particularly young women. Women are affected twice as much as men.

It has been increasingly associated with ketotic states associated with diabetes, fasting, and post-bariatric surgery.

In some patients, prurigo pigmentosa has been associated with systemic diseases like Sjogren syndrome and eating disorders like anorexia nervosa. It has also been described in people with atopy, as well as in pregnancy.

What causes prurigo pigmentosa?

The exact role of carbohydrate exclusion and ketosis in the development of prurigo pigmentosa has not yet been elucidated.

Several other mechanisms have been proposed for prurigo pigmentosa, including friction with clothing or contact. allergy to trichlorphenol, chromium in acupuncture needles, chromium in detergent and nickel.

How does prurigo pigmentosa appear?

The clinical characteristics of prurigo pigmentosa are:

• A pruritus rash (itching), which may come back
• Swollen, raised red spots (papules) that merge to form a lattice pattern (similar to a network)
• Symmetrical distribution in the trunk that most often affects the upper back, sacrum (natal cleft), abdomen and chest
• Rare involvement of the face or extremities.
• Save of mucous membranes hair and nail
• Lattice hyperpigmented patches after resolution of the inflammatory phase of the rash.

Histopathology of prurigo pigmentosa

There is a distinct histopathology in prurigo pigmentosa.

• Early injury: shallow perivascular neutrophilic infiltrateand some necrotic keratinocytes
• Injury developed: irregular lymphocytic infiltrate and necrosis of numerous keratinocytes
• Late injury: lymphocytic infiltrate, scale–Cortexand melanophages

What is the treatment for prurigo pigmentosa?

Adding carbohydrates to the diet may be beneficial if the patient is on a ketogenic diet or has undergone prolonged fasting or stomach surgery.

Dapsone and tetracycline antibiotics are effective in treating prurigo pigmentosa during the inflammatory phase of the disease. These treatments are believed to work by interfering with movement and the function of neutrophils. Macrolide antibiotics such as erythromycin have recently been shown to be useful as well. It is not clear if the antibacterial action of antibiotics is relevant.

Current and systemic corticosteroids are not effective for prurigo pigmentosa.

To date, there are no effective treatments for hyperpigmentation that develops in the later stages of the disease. Over time it fades away.