Background: Prurigo pigmentosa (PP) is a rare inflammatory dermatosis characterized by pruritic erythematous papules that coalesce to form a reticulate pattern. PP is often misdiagnosed, and patients are treated with ineffective therapies. Although the majority of reports about PP are from East Asia, patients of all backgrounds can be affected.Objectives: To perform a systematic review of reported PP cases with the purpose of summarizing the clinical presentation and treatment of PP.Methods: MEDLINE and Embase were searched for original articles describing PP. We identified 115 studies from 24 countries representing 369 patients to include in the analysis.Results: Of the 369 patients included in the analysis, the mean age was 25.6 years (range: 13-72 years) with 72.1% (266 of 369) female. Risk factors or aggravating factors were described in 52.3% (193 of 369) of patients and included dietary changes (25.5%, 94 of 369), friction (8.4%, 31 of 369), sweat (7.6%, 28 of 369), and ketonuria (5.1%, 19 of 369). Of those patients who experienced PP following dietary changes, 40.4% (38 of 94) started a ketogenic diet. Minocycline monotherapy was the most frequently prescribed treatment for PP (20.9%, 77 of 369), achieving complete resolution in 48.1% (37 of 77) of patients.Conclusions: PP is sometimes associated with ketogenic diets and can be effectively managed with oral tetracyclines.

Squamous cell carcinoma (SCC) can present as a rare complication of longstanding hidradenitis suppurativa (HS) lesions. Limited data exist on characteristics and outcomes of SCC development within HS lesions. The purpose of this review is to conduct a literature review of previously reported cases of SCC development in pre-existing HS lesions.EMBASE and MEDLINE searches were conducted in OVID on June 25, 2020, to yield 59 studies. Of the 95 patients (mean age: 52.9 years) who developed a total of 122 SCCs within HS lesions, the majority were males (77.9%, n = 74/95). The most common sites of SCC were the gluteal region (47.5%, n = 58/122), the perianal region (18.9%, n = 23/122), and the genitals (13.9%, n = 17/122). The mean duration between HS onset and SCC development was 25.5 years. Of the patients that had outcomes reported, 54.0% (n = 34/ 63) experienced SCC metastasis, 43.1% (n = 28/65) experienced SCC recurrences, and 58.7% (n = 44/75) experienced a mortality outcome. The most common documented reasons for death included metastasis (34.1%, n = 15/44) and sepsis (13.6%, n = 6/44).Patients with longstanding HS lesions can develop SCCs with a high rate of metastasis and mortality. Thus, chronic HS lesions, especially in the gluteal, perianal, genital, and perineal regions, should be monitored regularly for timely SCC diagnosis and management.

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Background Palmoplantar pustulosis (PPP) and palmoplantar pustular psoriasis (PPPP) are chronic inflammatory skin conditions characterized by eruptions of sterile pustules on the palms and/or soles. Biologic use has been associated with PPP and PPPP development in the literature.Objectives To identify PPP and PPPP associated with biologics and summarize reported treatments and outcomes.Methods We systematically searched in MEDLINE and Embase for articles that reported PPP or PPPP during biologic treatment. After a full-text review, 53 studies were included for analysis. ResultsWe identified 155 patients with PPP/PPPP onset during biologic treatment, with a mean age of 44.1 years and a female preponderance (71.6%). The most frequently reported biologics were adalimumab (43.9%) and infliximab (33.3%). IL-17 inhibitors, secukinumab (7.6%) and brodalumab (1.5%), were reported only in association with PPPP.Overall, 58.8% of patients had complete remission (CR) in 3.6 months and 23.5% had partial remission (PR) in 3.7 months. The most common treatments that led to CR were topical corticosteroids (n = 16) and biologic switching (n = 8).Conclusions Clinicians should anticipate PPP or PPPP as potential drug reactions to biologics such as adalimumab and infliximab. Large-scale studies are required to confirm our findings and further explore the pathogenesis for biologic-associated PPP and PPPP.