Chronic itch: emerging treatments following new research concepts.

Until recently, itch pathophysiology was poorly understood and treatments were poorly effective in relieving itch. Current progress in our knowledge of the itch processing, the numerous mediators and receptors involved has led to a large variety of possible therapeutic pathways. Currently, inhibitors of IL-31, IL-4/13, NK1 receptors, opioids and cannabinoids, JAK, PDE4 or TRP are the main compounds involved in clinical trials. However, many new targets, such as Mas-related GPCRs and unexpected new pathways need to be also explored.

Emerging Treatments and Novel Pathways in Pruritus.

Itch treatment is a major challenge in the dermatologist's practice. We encounter patients suffering from pruritus on a regular basis, and often lack diverse treatment options to adequately respond to the patients' needs. In the last 20 years, novel pathways have been investigated that were beyond the scope of histamine. Although most did not result in a molecule available on the Canadian market, it is interesting and important as health care providers to stay up to date with new neuronal pathways involved in itch transmission and potential new therapeutic options. In this review, we will discuss pathways targeted in new topical treatments such as antagonist of proteinase-activated receptor-2, the endocannabinoid system, neurotrophins and tropomyosin-related kinase A receptor, the transient receptor potential-vanilloid or transient receptor potential-melastatine ion channels. New systemic therapies are now focusing on antagonizing the neurokinin receptor, modulating the opioidergic system, or targeting itch cytokines such as interleukin-31.

An interesting case of pyoderma gangrenosum with immature hystiocytoid neutrophils.

We present a unique case of a 36-year-old male who developed more than 20 pyoderma gangrenosum (PG) ulcers showing on histopathology a dense inflammatory infiltrate composed of histiocytoid mononuclear immature cells with a strong positivity for myeloperoxidase and Leder stain, suggesting a myeloid lineage in the absence of a concomitant myeloproliferative disorder. Histiocytoid Sweet syndrome (SS) is now recognized as a histological subtype of SS. Although PG and SS belong to the spectrum of neutrophilic diseases, to the best of our knowledge, this is the first case of a "Histiocytoid pyoderma gangrenosum" encompassing immature granulocytes in the absence of leukemia cutis.

Tazarotene 0.1% Cream as Monotherapy for Early-Stage Cutaneous T-Cell Lymphoma.

BACKGROUND: Numerous treatments are available for cutaneous T-cell lymphoma (CTCL), including systemic retinoids. Very few data are available on topical retinoids. OBJECTIVES: The aim of this study was to evaluate the safety and efficiency of tazarotene as monotherapy for early-stage CTCL. METHODS: An open-label, prospective study of tazarotene as monotherapy for stages IA to IIA CTCL was conducted. Index lesions on 10 patients were followed for 6 months on treatment, plus at least 6 months off treatment. RESULTS: Six patients (60%) showed complete response (CR). Erythema, scaling, thickness, and lesion area decreased progressively throughout treatment. The mean time to CR was 3.8 months; CR was durable for at least 6 months in 83%. Of the 4 patients (40%) without CR, 2 (20%) had stable disease and 2 (20%) stopped the medication because of local side effects; none showed progression. CONCLUSIONS: This is the first Canadian trial providing evidence that topical tazarotene has excellent potential as a monotherapy agent for stages I to IIA CTCL.