Abstract Urticaria is a distinctive pattern of inflammatory re sponse of the skin and/or mucous membranes charac terized by the sudden appearance of vanishing wheals, angioedema, or both, associated with pruritus. Acute forms are frequent and limited to outbreaks of less than 6 weeks; while the chronic ones have a prevalence of less than 1%, longer duration and can be spontaneous or inducible. The etiopathogenic mechanisms involved in this disease include autoallergy, autoimmunity, and inflam mation with cell activation, mainly of the mast cell, leading to its degranulation with the release of vasoac tive mediators. Along its approach, diagnostic confirmation, search for indicators of its etiopathogenesis, detection of cofactors that can modulate its activity, recognition of comorbidi ties, evaluation of possible biomarkers and the assess ment of disease activity, impact and control are essential. The pharmacological management aims to control the symptoms, until the urticaria, which is self-resolv ing, is gone. This is described in a stepwise fashion with increasing complexity.

Resumen La urticaria es un patrón distintivo de respuesta inflamatoria de piel y/o mucosas caracterizada por la aparición súbita de ronchas evanescentes, angioedema o ambos, asociados a prurito. Las formas agudas son frecuentes y se limitan a brotes de menos de 6 sema nas; mientras que las crónicas tienen una prevalencia menor al 1%, mayor duración y pueden ser espontáneas o inducibles. Los mecanismos etiopatogénicos involucrados en esta enfermedad incluyen la autoalergia, la autoinmunidad y la inflamación con la activación celular, principalmente del mastocito, lo que lleva a su degranulación con libe ración de mediadores vasoactivos. En su abordaje son fundamentales la confirmación diagnóstica; la búsqueda de indicadores de su etiopa togenia; la detección de cofactores que pueden modular su actividad; el reconocimiento de comorbilidades; la evaluación de posibles biomarcadores y, el impacto en la calidad de vida, el registro de la actividad y el control de la enfermedad. El manejo farmacológico tiene por objetivo controlar los síntomas, mientras la urticaria resuelve de forma espontánea. Este se describe de forma escalonada con una complejidad creciente.

Abstract Background: The ECHO® (Extension for Community Healthcare Outcomes) project is a model of distance medical education developed in the United States to support health professionals in the management of patients with complex diseases. Since 2019, it has been implemented in atopic dermatitis (AD) in Argentina. The program consists of the periodic presentation of clinical cases by videoconference, virtual classes, and a permanently available open chat between professionals in charge of patients with AD and a group of experts. Objective: The objective of this study was to analyze the impact of the ECHO Project AD on the medical knowledge and medical skills of Argentinian health professionals when treating patients with AD. Methods: A survey was carried out among the participants in order to evaluate the impact of the program on the care of patients with AD. Results: ECHO Project AD revealed a significant improvement in the management of patients with AD. The program contributed to the interpretation and use of severity scores, use of phototherapy, and management and prescription of both classic and innovative topical and systemic treatments. Study limitations: The reduced number of participants and the short period of time. The answers of the survey may be biased by the enthusiasm of the participants. Conclusions: The ECHO project is an educational tool that enhances the medical skills of doctors and institutions, in which a climate of a partnership comes first and the participants look forward to learning from experiences, successes, and mistakes from one another, producing a scientific hub in constant evolution.

Methotrexate is an antimetabolite analog to folic acid that competitively inhibits the enzyme dihydrofolate reductase and thymidylate synthetase, essential for the synthesis of DNA and RNA. It is widely used in dermatology and its adverse effects on the skin and mucous membranes are varied, including mild and severe reactions. The appearance of erosions and skin ulcers as a manifestation of methotrexate cytotoxicity are quite infrequent. These would represent an early cutaneous sign of pancytopenia due to marrow toxicity secondary to this drug. In most of the cases there are cutaneous diseases prior to ulceration, mainly psoriasis. In the absence of underlying dermatitis, the presence of ulcerations is very rare. We present eight cases of patients with cutaneous signs of methotrexate poisoning, with and without previous dermatoses. Most of them associated mucositis and bone marrow involvement. Treatment guidelines are recommended.

El metotrexato es un antimetabolito análogo al ácido fólico que inhibe competitivamente la enzima dihidrofolato reductasa y timidilato sintetasa, indispensables para la síntesis de ADN y ARN. Se utiliza ampliamente en dermatología y sus efectos adversos en la piel y mucosas son variados, incluyendo reacciones leves y graves. Las erosiones y úlceras cutáneas como manifestación de citotoxicidad por metotrexato son infrecuentes y representarían un signo cutáneo temprano de pancitopenia por toxicidad medular secundaria a dicha droga. En la mayoría de los casos existen enfermedades cutáneas previas a la ulceración, principalmente psoriasis. En ausencia de dermatitis subyacente, la presencia de ulceraciones es excepcional. Se presentan ocho casos de pacientes con signos cutáneos de intoxicación por metotrexato, con y sin dermatosis previas. En la mayoría hubo asociación de mucositis y compromiso medular. Se recomiendan pautas de tratamiento.

Abstract Isolated angiokeratomas (AKs) are common cutaneous lesions, generally deemed unworthy of further investigation. In contrast, diffuse AKs should alert the physician to a possible diagnosis of Fabry disease (FD). Angiokeratomas often do not appear until adolescence or young adulthood. The number of lesions and the extension over the body increase progressively with time, so that generalization and mucosal involvement are frequent. Although rare, FD remains an important diagnosis to consider in patients with AKs, with or without familial history. Dermatologists must have a high index of suspicion, especially when skin features are associated with other earlier symptoms such as acroparesthesia, hypohidrosis, or heat intolerance. Once the diagnosis is established, prompt screening of family members should be performed. In all cases, a multidisciplinary team is necessary for the long-term follow-up and treatment.