Acral Prurigo Nodularis: A Case Report

Prurigo nodularis (PN) is a chronic skin disease that manifests with severe itchy, firm, hyperkeratotic nodules distributed on the trunk and the extremities symmetrically. Here, we report a unique presentation of PN. A 26-year-old male presented with multiple itchy nodules over the hands and feet sparing the trunk, which were confirmed histologically as PN. This is the first reported case of PN with exclusive acral distribution.


Introduction
Prurigo nodularis (PN) is a skin disease that manifests with severe itchy lesions described as well-defined, scaly, firm, hyperkeratotic itchy nodules [1]. The lesions are usually distributed on the trunk and the extremities symmetrically. This disease is challenging to treat, resulting in psychological and physical impacts, which can affect the quality of life [2]. The diagnosis is usually clinical and supported by biopsy [3]. Herein, we present a case of PN with an unusual presentation, which is limited to hands and feet.

Case Presentation
A 26-year-old male presented to the outpatient clinic with itchy skin lesions over his hands and feet for five years. Physical examination showed multiple well-defined, scaly, hyperpigmented nodules surrounded by violaceous borders with erosions over the dorsum of hands and feet (as shown in Figures 1, 2) and no lesions over the trunk or other areas of the body. He was managed first by clobetasol propionate 0.05% ointment and sodium fusidate 2% ointment two times a day, and levocetirizine 5 mg tablets at night with slight improvement. Past medical history was significant for Crohn's disease for six years on adalimumab 40 mg subcutaneously weekly, with no history of atopy or psychiatric illness. Workup for the patient was done, including complete blood count, liver function tests, renal function test, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and viral hepatitis B and C screening, all of which were normal. The differential diagnosis was PN, hypertrophic lichen planus, and Kaposi sarcoma. A skin biopsy was taken from the left foot lesion. The result showed parakeratosis, acanthosis, and papillary dermal fibrosis ( Figure  3) with elongation of rete ridges and superficial perivascular lymphocytes ( Figure 4). There was no evidence of lichen planus, which supports the diagnosis of PN. After the diagnosis was made, cyclosporine 350 mg orally daily was started. The lesions and pruritus improved on cyclosporine. However, due to unexpected exacerbation of diarrhea and other gastrointestinal symptoms, the gastroenterology consultant held the medication.

Discussion
It is well known that PN presents as itchy nodules that symmetrically affect the trunk and the extensors. However, our patient developed PN lesions over the hands and feet only (as seen in Figures 1, 2 year-old female with pruritus vulvae for three years that was resistant to treatment. Physical examination showed a dry patch measuring 0.5 x 1 cm on her vulva and a biopsy revealed PN [8]. Despite a few reported cases of unique presentations of PN, our case is the first reported case of PN with limited involvement over the acral areas only.

Conclusions
PN is a dermatological disease that classically affects the trunk and extremities. Few cases reported unusual presentations. However, this is the first case that reported exclusively acral distribution that has been proven with histopathology. PN should be considered for any patient with complaints of itchy hyperkeratotic nodules, even in acral presentation. After this report, we hope that other cases on acral distribution will be reported in the future.

Additional Information Disclosures
Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial