No SARS-CoV-2 antibody response in 25 patients with pseudo-chilblains.

Chilblain-like acral lesions have been identified in some coronavirus disease 2019 (COVID-19) patients. It has been suggested that these pseudo-chilblains could be a specific marker of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Most patients with these lesions have had negative polymerase chain reactions (PCRs), but some authors believe serology tests are likely to give positive results. We designed a prospective study including all patients with pseudo-chilblains treated in outpatient department in April and May 2020 and then performed SARS-CoV-2 PCR and serology tests on all available patients. We evaluated 59 patients, of whom 17 had undergone PCR before the study period, all with negative results. For the present study, we performed 20 additional PCRs, serology tests in 25 patients, and a parvovirus B19 antibody test in 15 patients. All results were negative. Our findings counter the hypothesis that serology is likely to reveal SARS-CoV-2 infection in patients with pseudo-chilblains. One hypothesis for our negative results is that the time period between symptom onset and antibody production is longer in these patients; another is that the lesions are caused by behavioral changes during lockdown rather than SARS-CoV-2 infection. We nevertheless maintain that COVID-19 should be ruled out in people presenting with chilblain-like lesions.

Delayed hypersensitivity to palladium dichloride: 15-year retrospective study in a skin allergy unit.

BACKGROUND: Metal allergies are the most frequent causes of allergic contact dermatitis. Although the use of palladium is increasing, it is not included in any baseline series. OBJECTIVE: To assess the prevalence of hypersensitivity to palladium and to describe the clinical and demographic characteristics of patients who are sensitized to palladium dichloride (PdCl2 ). METHODS: A single-centre, retrospective study of 15 years of patch testing with the Spanish baseline series supplemented with PdCl2 2% pet. was performed. We collected clinical and demographic data and data on co-sensitization among the metals studied, and we compared patients who were sensitized to palladium, with or without co-sensitization to nickel, with the rest of the study population. RESULTS: Among the 3678 included patients, 730 (19.9%) were sensitized to nickel sulfate. The prevalence of sensitization to PdCl2 (n = 316, 8.6%) was higher than the prevalence of sensitization to potassium dichromate (n = 240, 6.5%) and similar to the prevalence of sensitization to cobalt chloride (n = 353, 9.6%). Only 26 (8.2%) of the patients sensitized to palladium were not co-sensitized to nickel. The percentage of men and patients aged ≥40 years was higher in this subgroup than in the patients with nickel co-sensitization. CONCLUSIONS: Given the high prevalence of hypersensitivity to PdCl2 , this metal salt should be included in the Spanish baseline series, notwithstanding the frequency of co-sensitization to nickel.

Presentation of pseudohypoparathyroidism and pseudopseudohypoparathyroidism with skin lesions: Case reports and review.

We report three cases of patients with pseudohypoparathyroidism or pseudopseudohypoparathyroidism. These diseases are considered GNAS inactivating mutation syndromes that are characterized by a diversity of alterations among which a particular phenotype and specific endocrine or ossification abnormalities may be found. These patients may present with hard cutaneous nodules, which can represent osteoma cutis. The presence of these lesions in pediatric patients should prompt the dermatologist's consideration of this group of diseases when reaching a diagnosis. A multidisciplinary team of pediatricians, endocrinologists, geneticists, and dermatologists should carefully evaluate these patients.

Retronychia a little-known cause of paronychia: A report of two cases in adolescent patients.

Retronychia is a clinical condition resulting from embedding of the nail plate into the proximal nail fold. We report two adolescent girls, 14 and 16 years of age, with a history of chronic proximal paronychia of the great toe, one of them developing osteomyelitis. After failure of treatment with several systemic antibiotics, nail avulsion was performed, leading us to the diagnosis of retronychia and with rapid and complete resolution of symptoms in both cases. Delay in diagnosis of retronychia can lead to local complications and prolonged discomfort.