|Year : 2021 | Volume
| Issue : 2 | Page : 134-136
Prurigo pigmentosa: A case report with clinical, dermoscopic, and histological findings
Sahal J Samarkandy, Bader A Alharbi, Basel B Almalki, Samer A Alamri
Department of Dermatology, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, King Saud Bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia
|Date of Submission||08-Jun-2020|
|Date of Acceptance||06-Aug-2020|
|Date of Web Publication||29-Mar-2022|
Dr. Sahal J Samarkandy
Department of Dermatology, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, King Saud Bin Abdulaziz University for Health Sciences, Jeddah
Source of Support: None, Conflict of Interest: None
Prurigo pigmentosa (PP) was originally reported in Japan. It is an uncommon inflammatory skin disorder that usually involves the neck and trunk and characterized by a sudden eruption of pruritic indurated macules, papules, and Vescio papules that involute, leaving a reticulated pigmentation. It commonly affects young adult females. PP was initially thought to have a predilection for the Asian race, however several cases have been reported worldwide. The exact etiology of PP is yet unclear. However, it has been associated with ketosis and a ketogenic diet. Oral antibiotic is a major treatment in this disorder, while topical steroid and antihistamines are not successful.
Keywords: Ketogenic diet, prurigo pigmentosa, pruritic
|How to cite this article:|
Samarkandy SJ, Alharbi BA, Almalki BB, Alamri SA. Prurigo pigmentosa: A case report with clinical, dermoscopic, and histological findings. J Dermatol Dermatol Surg 2021;25:134-6
|How to cite this URL:|
Samarkandy SJ, Alharbi BA, Almalki BB, Alamri SA. Prurigo pigmentosa: A case report with clinical, dermoscopic, and histological findings. J Dermatol Dermatol Surg [serial online] 2021 [cited 2022 Jul 2];25:134-6. Available from: https://www.jddsjournal.org/text.asp?2021/25/2/134/341207
| Introduction|| |
Prurigo pigmentosa (PP) is an uncommon inflammatory skin disorder that usually involves the neck and trunk and characterized by a sudden eruption of pruritic indurated macules, papules, and Vescio papules that involute, leaving a reticulated pigmentation. The cause of PP is not known. However, it has been associated multiple factors involving ketosis and a ketogenic diet. Oral antibiotic is considered to be the main treatment in this disorder, but topical steroid and antihistamines have been not effective. Herein, we report a case of a Saudi middle-aged female patient who developed skin rash over the chest and neck after adherence to a ketogenic diet.,
| Case Report|| |
A 38-year-old Saudi female, who is medically free, came to our dermatology clinic complaining of multiple pruritic, erythematous papules, vesicles, and reticulated macular hyperpigmentation involving the midchest and anterior and lateral sides of the neck for 4 weeks [Figure 1]a and [Figure 1]b. She had no mucous membrane involvement. Two weeks before the onset of the rash, she started a ketogenic diet. She tried a topical corticosteroid with no benefit. The patient denied a recent history of flu, insect bites, history of contact with sick people, or any medication usage. Moreover, she has no personal or family history of atopy. Dermoscopic findings revealed that surface erosion and crust on the right upper side with faint reticular pigmentation as shown in [Figure 1]c. A skin punch biopsy was performed, and the histological section revealed a superficial perivascular lymphocytic infiltrate with eosinophils that suggest a dermal hypersensitivity reaction [Figure 2]a and [Figure 2]b. Ketone-B was elevated (1.1 mmol/L). The diagnosis of PP was highly suspected, and the patient was given oral doxycycline 100 mg once per day for 1 week. After 1 week, her rash improved dramatically, leaving net-like hyperpigmentation [Figure 3]a and [Figure 3]b.
|Figure 1: (a) Multiple erythematous papules, vesicles, and reticulated macular hyperpigmentation involving the anterior and lateral sides of the neck and (b) the midchest. (c) Dermoscopic findings revealed surface erosion and crust on the right upper side with faint reticular pigmentation|
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|Figure 2: (a and b) Are showing a skin punch biopsy revealing a superficial perivascular lymphocytic infiltrate with eosinophils that suggest a dermal hypersensitivity reaction|
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|Figure 3: (a) Shows multiple net-like hyperpigmentations over the anterior chest and disappearance of the rash in the neck area is shown in (b)|
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| Discussion|| |
The majority of PP cases have been reported in Japan, nevertheless, several cases have been reported in different countries. PP is more common in females, typically in their early adulthood. In one study, Kim et al. reported fifty cases of PP, in which 36 were female. Clinically, PP initially presents as sudden pruritic erythematous papules and plaques in a characteristic reticular pattern involving the neck, chest, and trunk. After that, the lesions may turn into papulovesicles and vesicles, then finally resolve as pigmented macules within weeks. Similarly, our patient presented with typical morphology of PP and the lesions healed leaving net-like hyperpigmentation.
The etiopathogenesis of PP is not fully understood yet. However, several factors have been associated with the development of PP that involve ketosis and a ketogenic diet. Ketosis has been commonly linked to the development of PP since many of the reported PP's risk factors lead to ketosis, such as diabetes, strict diet, anorexia nervosa, and fasting.,,, In addition, the resolution of symptoms after resolution of ketosis indicates the involvement of ketosis in the pathogenesis of PP. Finally, neutrophils play a central role in the pathogenesis of PP based on the observation of neutrophil infiltration in the early stage, and second the clinical improvement with the antibiotics that impair the function and migration of neutrophils such as minocycline and dapsone.,,,,,,,
Histopathological features of PP differ according to the stage of the disease. In the initial phase, the neutrophils predominate in the perivascular space, followed by spongiosis, ballooning, and keratinocytes necrosis. Later, lymphocytes and eosinophils predominate. Finally, the epidermis becomes hyperplastic, hyperkeratotic, and hyperpigmented and melanophages are seen in the dermis. The biopsy result of our patient revealed a superficial perivascular infiltration with lymphocytes and eosinophils, suggesting that the lesions are in the intermediate stage.
One important differential diagnosis is confluent and reticulated papillomatosis also known as Gougerot–Carteaud syndrome, which shares similar features to PP, namely, the location of the rash, the reticular distribution, and the improvement with minocycline. However, PP is distinguished by severe pruritus and distinct histopathological features.
Antibiotics are currently the mainstay of the treatment. Dapsone and minocycline are effective in PP likely secondary to their interference with neutrophils migration and function. Recently, the use of doxycycline in PP is favored. Our patient showed dramatic improvement with doxycycline treatment with no side effects over a short period. Other reported lines of treatment are isotretinoin, macrolides, and potassium iodide. Treatment with corticosteroid showed conflicting results.
In summary, PP is an inflammatory skin disorder that has been strongly linked to several internal and external factors. Since its association with ketosis and ketogenic dieting, physicians need to consider the diagnosis of PP in patients presenting with this type of skin eruption who are on dieting. Furthermore, additional studies are needed to explore other factors that can lead to the development of PP.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]