Treatment and Management

Available treatment options for PP include cessation of the ketogenic diet, antibiotics, or administering insulin in patients with diabetes.3 Other treatment options, including topical steroids and a referral to a registered dietitian, may be helpful in some cases as well.

Cessation of Ketosis

In a case reported by Maco et al, PP spontaneously resolved after the reintroduction of carbohydrates when other treatment modalities were unsuccessful (oral diphenhydramine, loratadine, topical steroids).3 Treatment is typically successful after cessation of the keto diet, although hyperpigmentation may still be present beyond the acute eruption. The reintroduction of carbohydrates is critical along with maintaining a balanced diet.11

Antibiotics

Antibiotic use is advantageous in PP cases in which the ketogenic diet provides therapeutic value (eg, epilepsy, obesity, metabolic or neurologic disorders). Oral minocycline is typically the first line of therapy.4 Oral minocycline was the most reported antibiotic used to treat PP.20 Successful results using doxycycline, macrolide antibiotics, and dapsone [diaminodiphenyl sulfone] also have been reported.11 The effectiveness of antibiotic treatment suggests the possible linkages of gut dysbiosis and host immunity.3 In addition to the anti-inflammatory properties of antibiotics; the antibacterial effects may be the responsible mechanism due to the histologic presence of bacterial colonies on the skin.21 Since PP is characterized by neutrophil-mediated inflammation, antibiotics that affect neutrophil chemotaxis (ie, minocycline and doxycycline) are effective.3


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Topical Steroids or Antihistamines

Topical steroids, including triamcinolone acetonide 0.1% cream, are mainly used to treat the intense itching that accompanies PP. Corticosteroids and antihistamines have minimal effect in treating PP.6 These treatment modalities have also been unsuccessful in clearing up the residual hyperpigmentation resulting from PP.9

Insulin

Insulin administration may resolve PP induced by diabetic ketoacidosis (DKA) in patients with diabetes.9

Referral to Dietitian

Ketosis resolution may not be necessary to treat PP effectively in patients with specific metabolic or neurological disorders for whom a ketogenic diet is an invaluable therapy such as Alzheimer’s dementia, Parkinson’s disease, other cancers, obesity, autism spectrum disorder, and intractable seizure disorders. 3 Referral to a registered dietitian skilled in ketogenic therapies and the use of a modified ketogenic diet may be an option for these individuals.3

Outcomes

The prognosis of PP is good and most patients will recover completely. Correction of the nutritional or metabolic deficit should successfully treat PP within a matter of days to weeks, however, hyperpigmentation may persist for months to years.17

The patient in this case improved within 1 week of cessation of the ketogenic diet. A small amount of residual hyperpigmentation was present after 6 days of stopping the ketogenic diet. He canceled his follow-up dermatology appointment due to the rapid success of therapy.

Conclusion

Diagnosis of PP involves a comprehensive history, physical examination, and diet recall. With the help of a skilled dietitian, a modified ketogenic diet may also provide optimal results for patients wanting or needing to remain on this diet for other medical conditions benefiting from ketosis.

Erica K. Flamm BSN, RN, is currently enrolled in the DNP-FNP program at the University of North Florida. She has worked in the intensive care unit, operating room, and has launched and coordinated several cardiothoracic and vascular programs including transcatheter aortic valve replacement programs.

References

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17. Goh SW, Adawiyah J, Nor N, Yap F, Ch’ng P, Chang CC. Skin eruption induced by dieting – an underdiagnosed skin disease in Malaysia. Malays Fam Physician. 2019;14(1):42-46.

18. Shevchenko A, Valdes-Rodriguez R, Hsu S, Motaparthi K. Prurigo pigmentosa: case series and differentiation from confluent and reticulated papillomatosis. JAAD Case Rep. 2017;4(1):77-80. doi:10.1016/j.jdcr.2017.07.027

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