Subsets of T lymphocytes in the lesional skin of pityriasis rosea

Immunological aspects of COVID-19 related skin manifestations: revisiting pathogenic mechanism in the light of new evidence

The newly emerged coronavirus disease 2019 (COVID‐19), induced by a novel strain of the coronavirus family, named severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), is a rapidly spreading global threat. This virus affects a fair number of tissues in the human body by availing itself of potential target receptors like Angiotensin‐Converting Enzyme 2 (ACE2). Presenting with diverse clinical manifestations, COVID‐19 has raised the urge for extensive research in different medical fields, including dermatology. Developing a comprehensive knowledge of cutaneous manifestations is highly important as it can help us in early diagnosis and better management of the ongoing pandemic. The dermatological presentations of COVID‐19 are classified into main categories of vascular and non‐vascular (exanthematous) patterns. Though not yet fully confirmed, the pathogenesis of these cutaneous presentations has been suggested to be more related to the overactivation of the immune system. In this review, we discuss in detail the clinical features of the diverse skin lesions in COVID‐19 patients and the imperative role of the immune system in their pathogenesis and development. Furthermore, we will discuss the reasons behind the accentuation of skin lesions in COVID‐19 compared to the same virus family predecessors.

Pityriasis Rosea: An Updated Review

BACKGROUND

Pityriasis rosea is a common acute, self-limited papulosquamous dermatosis that primarily affects children and young adults. The condition and its clinical variants may pose a diagnostic challenge, especially in the absence of the herald patch.

OBJECTIVE

This article aimed to familiarize pediatricians with clinical manifestations, evaluation, diagnosis, and management of pityriasis rosea.

METHODS

A search was conducted in March 2020 in Pubmed Clinical Queries using the key term " pityriasis rosea". The search strategy included all clinical trials (including open trials, non-randomized controlled trials, and randomized controlled trials), observational studies, and reviews (including narrative reviews and meta-analyses) published within the past 10 years. Only papers published in the English literature were included in this review. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Pityriasis rosea occurs mainly in individuals between 10 and 35 years of age with a peak during adolescence. Human herpesvirus (HHV)-7 and HHV-6 have been implicated as the causative agents in some patients with pityriasis rosea. A mild prodrome consisting of headaches, fever, malaise, fatigue, anorexia, sore throat, enlarged lymph nodes and arthralgia is present in about 5% of patients. The most common presenting sign, found in approximately 80% of patients, is a "herald" or "mother" patch which is larger and more noticeable than the lesions of the later eruption. A generalized, bilateral, symmetrical eruption develops in approximately 4 to 14 days and continues to erupt in crops over the next 12 to 21 days. Typical lesions are 0.5 to 1 cm, oval or elliptical, dull pink or salmon-colored macules with a delicate collarette of scales at the periphery. The long axes tend to be oriented along the skin lines of cleavage (Langer lines). Lesions on the back may have a characteristic "Christmas tree", whereas lesions on the upper chest may have a V-shaped pattern. There are many conditions that may mimic pityriasis rosea. Pityriasis rosea in the absence of the herald patch and its variants may pose a diagnostic challenge. The typical course is 6 to 8 weeks. In the vast majority of cases, reassurance and symptomatic treatment should suffice. Active intervention may be considered for individuals with severe or recurrent pityriasis rosea and pregnant women with the disease. Treatment options include acyclovir, macrolides (in particular, erythromycin), and ultraviolet phototherapy. If active intervention is needed, there is evidence supporting the use of oral acyclovir to shorten the duration of illness.

CONCLUSION

Pityriasis rosea is a common, acute, self-limiting exanthematous skin disease that primarily affects children and young adults. The condition is characterized by a "herald patch" after which oval erythematous squamous lesions appear along Langer's lines of cleavage on the trunk and proximal extremities, giving it a "Christmas tree" appearance. The disease presenting in its classical form can easily be diagnosed. Clinical variants of the disease may pose a diagnostic challenge for the general pediatrician. Knowledge of the disease is essential to allow prompt diagnosis and to avoid unnecessary investigations.