Perniosis: Clinical and Histopathological Analysis

Painful Raynaud's mimics

Raynaud's syndrome is a common finding in many autoimmune conditions. Accurately diagnosing Raynaud's, and differentiating it from mimicking conditions, is imperative in rheumatologic diseases. Raynaud's syndrome and Raynaud's mimickers, especially painful Raynaud's mimickers, can prove a diagnostic challenge for the practicing rheumatologist. Painful Raynaud's mimickers can lead to increased patient stress and unnecessary medical work up; Healthcare providers need to be aware of Raynaud's mimickers when evaluating patient concerns of skin color changes and pain. The present narrative review aims to highlight Raynaud's syndrome, important painful mimickers that may be seen, diagnosis, and updated management recommendations.

Protective effect of Bifidobacterium animalis CGMCC25262 on HaCaT keratinocytes

Bifidobacteria are the most prevalent members of the intestinal microbiota in mammals and other animals, and they play a significant role in promoting gut health through their probiotic effects. Recently, the potential applications of Bifidobacteria have been extended to skin health. However, the beneficial mechanism of Bifidobacteria on the skin barrier remains unclear. In this study, keratinocyte HaCaT cells were used as models to evaluate the protective effects of the cell-free supernatant (CFS), heat-inactivated bacteria, and bacterial lysate of Bifidobacterium animalis CGMCC25262 on the skin barrier and inflammatory cytokines. The results showed that all the tested samples were able to upregulate the transcription levels of biomarker genes associated with the skin barrier, such as hyaluronic acid synthetase (HAS) and aquaporins (AQPs). Notably, the transcription of the hyaluronic acid synthetase gene-2 (HAS-2) is upregulated by 3~4 times, and AQP3 increased by 2.5 times when the keratinocyte HaCaT cells were co-incubated with 0.8 to 1% CFS. In particular, the expression level of Filaggrin (FLG) in HaCaT cells increased by 1.7 to 2.7 times when incubated with Bifidobacterial samples, reaching its peak at a concentration of 0.8% CFS. Moreover, B. animalis CGMCC25262 also decreased the expression of the proinflammatory cytokine RANTES to one-tenth compared to the levels observed in HaCaT cells induced with tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ). These results demonstrate the potential of B. animalis CGMCC25262 in protecting the skin barrier and reducing inflammatory response.

The role of eosinophils in the differential diagnosis of inflammatory skin diseases

Eosinophils are known to be present in inflammatory skin diseases, but their diagnostic utility is not well established. Upon review of the published status of lesional eosinophils, several categories were identified. 1) Lesional eosinophils highly characteristic such that, in their absence, the pathologist may question the diagnosis. These include arthropod bite reactions and scabies, urticarial dermatitis, and other eosinophilic dermatoses. 2) Lesional eosinophils rare or absent, such that, in their presence, the pathologist may question the diagnosis. These include pityriasis lichenoides, graft versus host disease, and connective tissue disorders. 3) Lesional eosinophils variable and, while in some cases expected, are not required for diagnosis. These include drug reactions, atopic dermatitis and allergic contact dermatitis. 4) Lesional eosinophils variable and not expected but may be seen to a limited extent. These include lichen planus and psoriasis.

From Chilblains (Pernio) to Coeliac Disease-Should We Still Consider It Random?

Coeliac disease (CD) is a gluten-triggered, immune-mediated inflammatory disease occurring in genetically predisposed individuals, causing a variety of gastrointestinal and extraintestinal symptoms. The most common cutaneous association of CD is dermatitis herpetiformis, although recent reports have sought to link CD with other dermatological and autoimmune diseases. Chilblain, also called pernio, is usually a benign, superficial and localized inflammatory skin disorder that results from a maladaptive vascular response to non-freezing cold. We present a patient with pernio (chilblains) and newly diagnosed CD, with a significant intestinal lesion-total villous atrophy, as there are only two known cases of this feature associated with CD published in the literature. In the workup of chilblains (pernio) in children, an active case finding for coeliac disease should be conducted with coeliac-specific serology testing.

Population Characteristics, Symptoms, and Risk Factors of Idiopathic Chilblains: A Systematic Review, Meta-Analysis, and Meta-Regression

Background: Chilblains/perniosis is a non-freezing cold injury causing painful inflammatory skin lesions. Its pathogenesis remains poorly understood because it is often studied as secondary to other underlying conditions. Methods: We systematically investigated the population characteristics, symptoms, and predisposing factors of chilblains in healthy adults exposed to cool/cold environments. We screened PubMed, Embase, and Cochrane Library, and we adopted PRISMA reporting guidelines (PROSPERO: CRD42021245307). The risk of bias was assessed by two independent reviewers (RTI item bank). Random-effects model meta-analyses were performed to calculate the pooled prevalence of histopathological features. Mixed-effects meta-regressions were used to assess other sources of between-study heterogeneity. Results: Thirteen studies (477 patients) were included. Chilblains affect more women than men, up to 12% of the body skin surface, and most frequently, the hands and fingers. Meta-analyses of nine studies (303 patients) showed a frequent presence of perivascular lymphocytic infiltrate (81%), basal epidermal-cell layer vacuolation (67%), papillary dermal edema (66%), and perieccrine lymphocytic infiltrate (57%). Meta-regressions (p ≤ 0.05) showed that smoking and frequent occupational exposure to water increase the likelihood of histopathological features. Conclusions: The population characteristics, symptoms, and predisposing factors of chilblains revealed in this analysis should be incorporated in medical care to improve the condition’s diagnosis and management.

SARS-CoV-2 Vaccination and Chilblain-like Lesions: What Do We Know so Far?

INTRODUCTION

The coronavirus pandemic has caused massive damage to global health care and the economy. The vaccination program has been paced around the globe to return as soon as possible to pre-COVID time. Although all the vaccines have been approved after the rigorous clinical and safety trials, some adverse effects have surfaced and are being reported from different parts of the world. One such side effect is chilblain-like lesions following the COVID vaccination. Chilblain lesions, also known as pernio, are an inflammatory condition usually affecting the acral regions of the body. It is mostly reported from cold and damp areas and has multiple causes associated with it.

OBJECTIVE

This study aims to review the publicly available data and to provide concise and comprehensive information as well as evaluate the potential pathology, clinical approach, and management of CLL post-vaccination.

METHODS

An extensive literature search over PubMed, Cochrane library, Google Scholar, and Clinicaltrails. gov from inception till 5th October 2021, without any restriction of language was carried out. All the recruited articles were reviewed, and their bibliographies were also screened for any relevant information.

RESULTS

12 studies (10 case reports and 2 case series) were retrieved reporting the incidence of CLL post-vaccination. 8 studies reported incidence in female patients while 5 reported in males, with one study mentioning no gender. Moreover, most of them were either from Europe or the United States of America, except for two cases, reported from Turkey.

CONCLUSIONS

Although the overall incidence of Chilblains following COVID-19 vaccination is low, there is still a strong need to find out the exact mechanism behind this to redefine the safety and administration criteria of the vaccines and to formulate a proper management protocol.

Chilblains in immune-mediated inflammatory diseases: a review

Chilblains were first described over a hundred years ago as cutaneous inflammatory lesions, typically on the digits, occurring on cold exposure. Chilblains can be primary, or secondary to a number of conditions such as infections, including COVID-19, and immune-mediated inflammatory disorders (IMIDs) with SLE being the commonest. Chilblain lupus erythematosus (CHLE) was first described in 1888 as cold-induced erythematous lesions before the terms 'chilblains' or 'perniosis' were coined. Diagnostic criteria exist for both chilblains and CHLE. Histopathologically, CHLE lesions show interface dermatitis with perivascular lymphocytic infiltrate. Immunofluorescence demonstrates linear deposits of immunoglobulins and complement in the dermo-epidermal junction. This narrative review focuses on chilblains secondary to immune-mediated inflammatory disorders, primarily the epidemiology, pathogenesis and treatment of CHLE.

Relationship Between the Onset of Ménière's Disease and Sympathetic Hyperactivity

Objective

The pathogenesis of Ménière's disease is still largely unknown; however, it is known to be strongly associated with stress. Excessive stress can cause hyperactivity of the sympathetic autonomic nervous system. With the aim of understanding changes in sympathetic hyperactivity before and after Ménière's disease, we compared autonomic nervous function in patients in a stable phase of Ménière's disease and that in healthy adults. We also gathered data over about 10 years on autonomic nervous function immediately before a Ménière's attack.

Study Design

Prospective study.

Patients

Autonomic nervous function was analyzed in 129 patients in a stable phase of Ménière's disease 31 healthy adult volunteers. In nine patients, autonomic nervous function was also measured immediately before and after treatment of a vertigo attack.

Main Outcome Measure

Power spectrum analysis of heart rate variability (HRV) of EEG/ECG and an infrared electronic pupillometer were used. Sympathetic and parasympathetic nervous function was measured.

Results

There were no statistically significant differences in autonomic nervous function determined by HRV and electronic pupillometry between patients in a stable phase of Ménière's disease and healthy adults. Sympathetic function as measured by electronic pupillometry parameters VD and T5 showed no difference between the affected and unaffected sides in the baseline data measured in the stable phase (VD: affected side is 31.02 ± 6.16 mm/sec, unaffected side is 29.25 ± 5.73 mm/sec; T5: affected side is 3.37 ± 0.43 msec, unaffected side is 3.25 ± 0.39 msec). In contrast, all nine patients whose HRV data had been obtained just before an attack showed marked suppression of the parasympathetic nervous system and activation of the sympathetic nervous system. Electronic pupillometry also revealed an overactivation of the sympathetic nervous system on the affected side, just before the attacks. Analysis of sequential changes after the onset of an attack revealed that overactivation on the affected side was reduced after treatment, and no difference between affected and unaffected sides was observed 3 days after treatment.

Conclusion

Detailed analysis of autonomic nervous function showed that immediately before an attack of Ménière's disease, the sympathetic nervous system on the affected side was strongly overactivated.

Cutaneous eccrine inflammation and necrosis: review of inflammatory disorders affecting the eccrine apparatus including new associations

Despite being frequently overlooked during the examination of histopathological sections, eccrine sweat glands can offer clues for diagnosing various skin conditions. They provide important functions and can lead to several diseases when inflamed or injured. This review article provides information regarding eccrine physiology as well as well-established and novel entities that occur in association with eccrine gland pathology.

A clinicopathological description of COVID-19-induced chilblains (COVID-toes) correlated with a published literature review

Background

The abundance of publications of COVID‐19‐induced chilblains has resulted in a confusing situation.

Methods

This is a prospective single‐institution study from 15 March to 13 May 2020. Thirty‐two patients received PCR nasopharyngeal swabs. Of these, 28 patients had a thoracic CT‐scan, 31 patients had blood and urine examinations, 24 patients had skin biopsies including immunohistochemical and direct immunofluorescence studies, and four patients had electron microscopy.

Results

COVID‐19‐induced chilblains are clinically and histopathologically identical to chilblains from other causes. Although intravascular thrombi are sometimes observed, no patient had a systemic coagulopathy or severe clinical course. The exhaustive clinical, radiological, and laboratory work‐up in this study ruled‐out other primary and secondary causes. Electron microscopy revealed rare, probable viral particles whose core and spikes measured from 120 to 133 nm within endothelium and eccrine glands in two cases.

Conclusion

This study provides further clinicopathologic evidence of COVID‐19‐related chilblains. Negative PCR and antibody tests do not rule‐out infection. Chilblains represent a good prognosis, occurring later in the disease course. No systemic coagulopathy was identified in any patient. Patients presenting with acral lesions should be isolated, and chilblains should be distinguished from thrombotic lesions (livedo racemosa, retiform purpura, or ischemic acral necrosis).

Cutaneous manifestations of lupus erythematosus: A practical clinicopathologic review for pathologists

Accurate diagnosis of connective tissue diseases is often challenging and relies on careful correlation between clinical and histopathologic features, direct immunofluorescence studies, and laboratory workup. Lupus erythematosus (LE) is a prototype of connective tissue disease with a variety of cutaneous and systemic manifestations. Microscopically, cutaneous LE is classically characterized by an interface dermatitis, although other histopathologic patterns also exist depending on the clinical presentation, location, and chronicity of the skin lesions. In this article, we review the clinical, serologic, histopathologic, and direct immunofluorescence findings in LE-specific and LE-nonspecific skin lesions, with an emphasis on lesser known variants, newly described features, and helpful ancillary studies. This review will guide general pathologists and dermatopathologists in accurately diagnosing and subclassifying cutaneous LE.

Adnexotropic Variants of the Interface Dermatitides: A Review

The interface dermatitides encompass a vast array of cutaneous entities which, at times, may present with particular clinical variants with adnexal predilection. Similarly, hair follicle and eccrine gland involvement of some of these entities has been observed on histopathology. This review aims to describe the various adnexotropic presentations of the interface dermatitides. Recognizing that the adnexa can be a frequent site of involvement of these conditions may aid dermatopathologists in making the correct diagnosis and avoid misinterpreting adnexotropism for other conditions such as the great imitator, mycosis fungoides.

Chilblain-Like Lesions (CLL) Associated With COVID-19 ("COVID Toes"): A Systematic Review

Reports of chilblain-like lesions (CLL) coinciding with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have been described in the literature, but this phenomenon has not been critically summarized. The aim of this paper is to summarize reports of CLL coinciding with SARS-CoV-2 infection to clarify the prevalence, clinical relevance, and prognostic value of these lesions. A literature search was conducted using the Embase, Pubmed, and Scopus databases from December 2019 to June 16, 2020 using the search terms ("COVID-19" OR "coronavirus" OR "2019-nCoV" OR "SARS-CoV-2") AND ("chilblain-like" OR "COVID toes" OR "acral"). Papers that described skin changes in patients with suspected or confirmed COVID-19 were included. A total of 31 papers were summarized, representing 813 cases of CLL. Available data suggests an equal gender distribution, mean age of 21 years, and median age of 14 years. Mild extracutaneous symptoms were reported in 53% of cases and 47% were asymptomatic. CLL occurred an average of 16 days after extracutaneous symptoms. Patients with CLL were positive for SARS-CoV-2 in 15% of cases. Lesions were mainly described as asymptomatic and/or pruritic erythematous to violaceous acral macules and plaques. Partial or complete resolution occurred in 85% of cases in a mean of 13 days. The most common histologic findings were perivascular and perieccrine superficial and deep lymphocytic infiltrates. Although a causal relationship between CLL and SARS-CoV-2 has not been confirmed, the temporal association and 15% positive SARS-CoV-2 rate in affected individuals should not be ignored.

COVID Purpura (Toes) Case Series: A Chilblains-Like Vasculopathy

ABSTRACT

Biopsies were taken from 4 patients who presented to their dermatologist with violaceous papules and plaques of the dorsal toes (COVID Toes) associated with varying degrees of severe acute respiratory syndrome coronavirus 2 exposure and COVID-19 testing. Major histopathologic findings were lymphocytic eccrine inflammation and a spectrum of vasculopathic findings to include superficial and deep angiocentric-perivascular lymphocytic inflammation, lymphocytes in vessel walls (lymphocytic vasculitis), endothelial swelling, red blood cell extravasation, and focal deposits of fibrin in both vessel lumina, and vessel walls. Interface changes were observed to include vacuolopathy and apoptotic keratinocytes at the basement membrane. Immunostains showed a dominant T-cell lineage (positive for T-cell receptor beta, CD2, CD3, CD5, and CD7). B-cells were rare and clusters of CD123-positive dermal plasmacytoid dendritic cells were observed surrounding eccrine clusters and some perivascular zones. The consistent perieccrine and vasculopathic features represent important pathologic findings in the diagnosis of COVID toes and are suggestive of pathogenetic mechanisms. Clinicopathologic correlation, the epidemiological backdrop, and the current worldwide COVID-19 pandemic favor a viral causation and should alert the physician to initiate a workup and the appropriate use of COVID-19 testing.

Pernio (Chilblains), SARS-CoV-2, and COVID Toes Unified Through Cutaneous and Systemic Mechanisms

Pernio or chilblains is characterized by erythema and swelling at acral sites (eg, toes and fingers), typically triggered by cold exposure. Clinical and histopathologic features of pernio are well described, but the pathogenesis is not entirely understood; vasospasm and a type I interferon (IFN-I) immune response are likely involved. During the coronavirus disease 2019 (COVID-19) pandemic, dermatologists have observed an increase in pernio-like acral eruptions. Direct causality of pernio due to COVID-19 has not been established in many cases because of inconsistent testing methods (often negative results) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, a form of COVID-19‒associated pernio (also called COVID toes) is probable because of increased occurrence, frequently in young patients with no cold exposure or a history of pernio, and reports of skin biopsies with positive SARS-CoV-2 immunohistochemistry. PubMed was searched between January 1, 2020, and December 31, 2020 for publications using the following keywords: pernio, chilblain, and acral COVID-19. On the basis of our review of the published literature, we speculate that several unifying cutaneous and systemic mechanisms may explain COVID-19‒associated pernio: (1) SARS-CoV-2 cell infection occurs through the cellular receptor angiotensin-converting enzyme 2 mediated by transmembrane protease serine 2, subsequently affecting the renin-angiotensin-aldosterone system with an increase in the vasoconstricting, pro-inflammatory, and prothrombotic angiotensin II pathway. (2) Severe acute respiratory syndrome coronavirus 2 cell infection triggers an immune response with robust IFN-I release in patients predisposed to COVID-19‒associated pernio. (3) Age and sex discrepancies correlated with COVID-19 severity and manifestations, including pernio as a sign of mild disease, are likely explained by age-related immune and vascular differences influenced by sex hormones and genetics, which affect susceptibility to viral cellular infection, the renin-angiotensin-aldosterone system balance, and the IFN-I response.

Idiopathic perniosis presenting as acral purpuric lesions: Clustering of cases before COVID-19 pandemic and their comparison with chilblain like lesions reported in the literature

Perniosis/chilblains are the acral inflammatory skin lesions developing in susceptible individuals as an abnormal reaction to cold. In the absence of a discernible cause, it is labeled as idiopathic perniosis (IP). With the ongoing COVID-19 pandemic, there was an upsurge of reports of chilblain like lesions (CLL) especially in young patients possibly implicated to the SARS-CoV-2 virus. Twelve clinically suspected and histopathologically confirmed cases of IP seen from November 2019 through February 2020 were retrospectively recruited. Clinical, dermoscopic, and histopathological characteristics of these were reviewed and compared with CLL reported in the literature. Mean age of patients was 26.58 ± 15.18 years with an equal male to female ratio. Characteristic histopathology findings were spongiosis (100%), dermal edema (100%), perivascular lymphocytic infiltrate (100%) with peri-eccrine accentuation (66.7%), keratinocyte necrosis (50%), focal basal vacuolar damage (58.3%), and lymphocytic vasculitis (58.3%). Significant dermoscopy findings were variable background color ranging from dull red and violaceous to copper red and brown orange, coiled vessels (44.4%) and orange-red structureless areas (63.9%). Lesions over palms and soles preferentially had white dots/clods and lines (38.9%). There appears no exclusive histopathological as well as dermoscopy features of CLL and IP, yet certain clues can be appreciated. Keratinocyte necrosis and severe dermal edema favors IP, whereas fibrin thrombi with involvement of both superficial and deep dermal vessels favor CLL. Dermoscopically presence of irregular, linear or branching vessels, red/purple dots and clods and gray brown reticule supports CLL while white dots/clods and lines supports IP.

Raynaud's phenomenon and related vasospastic disorders

Raynaud's phenomenon, which is characterized by episodic digital pallor, cyanosis and rubor upon exposure to cold environment or to stress, is relatively common, although the prevalence depends on the climate. Still, it is under-diagnosed, under-treated, and often confused with other conditions. Primary Raynaud's phenomenon (i.e., Raynaud disease) must be distinguished from secondary Raynaud's phenomenon (i.e., Raynaud syndrome) as long-term morbidity and outcomes differ vastly between the two conditions. Additionally, the practitioner must differentiate between Raynaud's phenomenon and related vascular disorders, such as acrocyanosis, pernio, and livedo reticularis. In this article, we review differences between the conditions and suggest an approach to diagnosis and treatment strategy for these disorders.

[Cutaneous disorders caused by physical damage mimicking rheumatic diseases]

The skin is the primary interface between the body and the environment. It is exposed to a variety of external physical factors to which it must respond in a dynamic manner. In the following review such cutaneous reactions to physical damage are discussed under the aspects of rheumatological differential diagnoses. In particular, circumscribed hyperpigmentation and hyperkeratosis, reactive patterns to cold, with or without humidity, and lightning are presented. Most of these disorders do not need extensive laboratory investigations or imaging techniques. Knowledge of such cutaneous disease symptoms due to physical damage prevents overdiagnostics and possible overtreatment.

Perniosis during the COVID-19 pandemic: Negative anti-SARS-CoV-2 immunohistochemistry in six patients and comparison to perniosis before the emergence of SARS-CoV-2

BACKGROUND

Acral inflammatory lesions that have some resemblance to idiopathic or autoimmune-associated perniosis (chilblains) have been described in multiple countries during the COVID-19 pandemic.

METHODS

We examined histopathologic findings in six consecutive such cases from five patients received in mid-May to mid-June of 2020, evaluating immunohistochemical staining for the SARS-CoV-2 nucleocapsid protein. We compared these six cases to eight cases diagnosed as perniosis between January and June of 2019.

RESULTS

Five of six lesions with perniosis-like histopathology during the COVID-19 pandemic had distinctive tight cuffing of lymphocytes; intravascular material was present in one case. SARS-CoV-2 immunohistochemical staining using an antibody directed at the nucleocapsid protein was negative in all six cases. Only one of eight specimens with microscopic findings of perniosis received prior to the COVID-19 pandemic had tightly cuffed perivascular lymphocytes, and none had obvious intravascular occlusion.

CONCLUSIONS

A tightly cuffed pattern of perivascular lymphocytes is a feature of perniosis during the COVID-19 pandemic. The absence of SARS-CoV-2 nucleocapsid protein in these cases suggests against the virus being directly present in these lesions.

SARS-CoV-2 endothelial infection causes COVID-19 chilblains: histopathological, immunohistochemical and ultrastructural study of seven paediatric cases

Background

Chilblains (‘COVID toes’) are being seen with increasing frequency in children and young adults during the COVID‐19 pandemic. Detailed histopathological descriptions of COVID‐19 chilblains have not been reported, and causality of SARS‐CoV‐2 has not yet been established.

Objectives

To describe the histopathological features of COVID‐19 chilblains and to explore the presence of SARS‐CoV‐2 in the tissue.

Methods

We examined skin biopsies from seven paediatric patients presenting with chilblains during the COVID‐19 pandemic. Immunohistochemistry for SARS‐CoV‐2 was performed in all cases and electron microscopy in one.

Results

Histopathology showed variable degrees of lymphocytic vasculitis ranging from endothelial swelling and endotheliitis to fibrinoid necrosis and thrombosis. Purpura, superficial and deep perivascular lymphocytic inflammation with perieccrine accentuation, oedema, and mild vacuolar interface damage were also seen. SARS‐CoV‐2 immunohistochemistry was positive in endothelial cells and epithelial cells of eccrine glands. Coronavirus particles were found in the cytoplasm of endothelial cells on electron microscopy.

Conclusions

Although the clinical and histopathological features were similar to other forms of chilblains, the presence of viral particles in the endothelium and the histological evidence of vascular damage support a causal relation of the lesions with SARS‐CoV‐2. Endothelial damage induced by the virus could be the key mechanism in the pathogenesis of COVID‐19 chilblains and perhaps also in a group of patients severely affected by COVID‐19 presenting with features of microangiopathic damage.

What is already known about this topic?

Despite the high number of cases of chilblains seen during the COVID‐19 pandemic, a definite causative role for SARS‐CoV‐2 has not yet been proven.

Different pathogenetic hypotheses have been proposed, including coagulation anomalies, interferon release and external factors.

What does this study add?

The demonstration of SARS‐CoV‐2 in endothelial cells of skin biopsies by immunohistochemistry and electron microscopy confirms that these lesions are part of the spectrum of COVID‐19.

Virus‐induced vascular damage and secondary ischaemia could explain the pathophysiology of COVID‐19 chilblains.

Our findings support the hypothesis that widespread endothelial infection by SARS‐CoV‐2 could have a pathogenetic role in the severe forms of COVID‐19.

Linked Comment:  Wetter. Br J Dermatol 2020; 183:611.

Vulnerability of the skin barrier to mechanical rubbing

Skin barrier function is the battlefront for preventing permeation of harmful substances and infectious diseases. However, it can be destroyed by mechanical forces, as shown in many studies. Excess rubbing may increase the permeability of the skin to aqueous material. Although the skin barrier plays an important physiological role in humans, the vulnerability of skin to mechanical rubbing is poorly understood. Therefore, we investigated the effects of rubbing on the skin in vitro; skin damage was quantified by laser-induced fluorescence. Microscopic observation showed that keratinocytes in the stratum corneum sustained traumatic damage, which reduced the barrier function in that region. The permeability of the skin to an aqueous solution increased with rubbing frequency and load, and rubbing markedly reduced the barrier function of the stratum corneum. To understand the mechanisms underlying the skin damage, we developed a simple mathematical model assuming that the skin is a viscoelastic material. We hypothesized that the increased skin permeability was caused by the damage sustained by keratinocytes in the stratum corneum, and that the permeability was proportional to the time-averaged strain. Our theoretical results showed quantitative agreement with the experimental results and illustrated that rubbing and strain relaxation play key roles in rubbing-induced permeation.

A clinical, histopathological and laboratory study of 19 consecutive Italian paediatric patients with chilblain-like lesions: lights and shadows on the relationship with COVID-19 infection

Background

Acral chilblain‐like lesions are being increasingly reported during COVID‐19 pandemic. However, only few patients proved positivity for SARS‐CoV‐2 infection. The relationship between this skin manifestation and COVID‐19 infection has not been clarified yet.

Objective

To thoroughly characterize a prospective group of patients with chilblain‐like lesions and to investigate the possible relationship with SARS‐CoV‐2 infection.

Methods

Following informed consent, patients underwent (i) clinical evaluation, (ii) RT‐PCR and serology testing for SARS‐CoV‐2, (iii) digital videocapillaroscopy of finger and toe nailfolds, (iv) blood testing to screen for autoimmune diseases and coagulation anomalies, and (v) skin biopsy for histopathology, direct immunofluorescence and, in selected cases, electron microscopy.

Results

Nineteen patients, all adolescents (mean age: 14 years), were recruited. 11/19 (58%) of them and/or their cohabitants reported flu‐like symptoms one to two months prior to skin manifestation onset. Lesions were localized to toes and also heels and soles. Videocapillaroscopy showed pericapillary oedema, dilated and abnormal capillaries, and microhaemorrhages both in finger and toe in the majority of patients. Major pathological findings included epidermal basal layer vacuolation, papillary dermis oedema and erythrocyte extravasation, perivascular and perieccrine dermal lymphocytic infiltrate, and mucin deposition in the dermis and hypodermis; dermal vessel thrombi were observed in two cases. Blood examinations were normal. Nasopharyngeal swab for SARS‐CoV‐2 and IgG serology for SARS‐CoV‐2 nucleocapsid protein were negative. Importantly, IgA serology for S1 domain of SARS‐CoV‐2 spike protein was positive in 6 patients and borderline in 3.

Conclusions

Chilblain‐like lesions during COVID‐19 pandemic have specific epidemiologic, clinical, capillaroscopic and histopathological characteristics, which distinguish them from idiopathic perniosis. Though we could not formally prove SARS‐CoV‐2 infection in our patients, history data and the detection of anti‐SARS‐COV‐2 IgA strongly suggest a relationship between skin lesions and COVID‐19. Further investigations on the mechanisms of SARS‐CoV‐2 infection in children and pathogenesis of chilblain‐like lesions are warranted.

Chilblain-like acral lesions during the COVID-19 pandemic ("COVID toes"): Histologic, immunofluorescence, and immunohistochemical study of 17 cases

BACKGROUND

During the coronavirus disease 2019 pandemic, several acral chilblain-like lesions were observed in young patients with suspected, but mostly unconfirmed, infection with severe acute respiratory syndrome coronavirus 2. The histopathologic aspect of these lesions is as yet poorly known.

OBJECTIVE

To investigate the pathologic features of chilblain-like lesions.

METHODS

Biopsies were obtained from 17 cases of chilblain-like lesions during the coronavirus disease 2019 pandemic in France and were studied by routine histologic examination, immunohistochemistry, and direct immunofluorescence. The patients had suspected but unconfirmed infection with severe acute respiratory syndrome coronavirus 2 (negative nasopharyngeal polymerase chain reaction and serologic test results).

RESULTS

Chilblain-like lesions showed many features in common with those reported in idiopathic and autoimmune-related chilblains, including epidermal necrotic keratinocytes, dermal edema, perivascular and perieccrine sweat gland lymphocytic (predominantly CD3/CD4⁺) inflammation, and frequent vascular changes (endothelialitis, microthromboses, fibrin deposition, and immunoreactant deposits on vessels).

CONCLUSIONS

Chilblain-like lesions show histopathologic features similar to those of idiopathic and autoimmune-related chilblains, with a high rate of vascular changes and direct immunofluorescence positivity. The role of severe acute respiratory syndrome coronavirus 2 in the development of these puzzling lesions remains to be elucidated.

Chilblains

Idiopathic chilblain is a relatively common yet poorly recognized acrosyndrome. This literature review aims to better understand and draw attention to this disorder. Chilblain is a localized inflammation of the skin that occurs on exposure to cold but non-freezing wet weather. It usually resolves spontaneously. The etiology is uncertain, but vasospasm seems to play a role in this abnormal reaction to cold. Diagnosis is most often based on clinical presentation, but a skin biopsy can be useful in dubious cases. In histology, dermal edema and an inflammatory infiltrate are usually present. A distribution of the infiltrate particularly around the eccrine gland is typical. Systemic symptoms and underlying autoimmune disease should be screened. Avoiding cold and keeping extremities warm is the first recommendation for management, as well as smoking cessation. Calcium channel blockers (in particular nifedipine) seems to be the treatment that has been most evaluated in chilblains. However, their effectiveness is not confirmed by all studies. Topical betamethasone is often used but its effect has not been confirmed by randomized clinical trials. Other treatments, such as pentoxifylline, hydrochloroquine and topical nitroglycerin have shown positive effects only in a reduced number of patients. Acupuncture seems to bring a benefit.

Mucin as a diagnostic clue in dermatopathology

Mucins are high-molecular weight glycoproteins typically found in normal skin in small amounts. There are several reports regarding different types of cutaneous mucinosis. In this report, we discuss mucins in dermatopathology as a diagnostic clue of some well-known entities and some less frequent cutaneous diseases. We also emphasize mucin as a sign in the differential diagnosis between conditions that show histopathological overlap. Lastly, we discuss the locations and circumstances in which mucin could be considered almost normal or physiological.

Perniosis A Case Report with Literature Review

Perniosis, or chilblain, is an uncommon condition of the acral skin. Presented herein is a case report of a 65-year-old otherwise healthy construction worker with perniosis. He had a 3-year history of lesions on the fingers and toes brought on by cold, damp weather. On initial presentation, a biopsy sample was taken of a hallux lesion, and the patient was given a trial course of nifedipine therapy. Follow-up at 3 weeks showed complete relief of symptoms with nifedipine use, and the biopsy results confirmed the diagnosis. The etiology and pathogenesis of perniosis are reviewed. Differential diagnoses and treatment options are reviewed and discussed. Nifedipine therapy has been shown to be effective and should be considered the standard of care in the treatment of perniosis along with avoidance of cold, damp environments, with protection using gloves and warm socks.

Vasospasm Is a Consistent Finding in Pernio (Chilblains) and a Possible Clue to Pathogenesis

BACKGROUND/AIMS

Pernio (chilblains) is an inflammatory condition classically characterized by localized erythema and swelling of acral sites upon exposure to cool and damp conditions. We sought to determine whether cold-induced vasospasm has a role in the development of pernio.

METHODS

We retrospectively reviewed 5 patients with pernio who were seen at our institution between January 1, 2000 and December 31, 2011, and had undergone a noninvasive arterial vascular study of the upper extremities that corresponded to a site of clinical involvement of pernio and who had also undergone vasospastic testing and ice water immersion as part of the noninvasive arterial vascular study protocol.

RESULTS

Vascular testing in all patients (mean age 37.8 years; 4 women) demonstrated vasospasm with ice water immersion.

CONCLUSION

Our findings suggest that vasospasm likely has a role in the pathophysiology of pernio and may also provide a rationale for the pharmacological treatment of vasospasm in patients with pernio.

Clinical characteristics, etiologic associations, laboratory findings, treatment, and proposal of diagnostic criteria of pernio (chilblains) in a series of 104 patients at Mayo Clinic, 2000 to 2011

OBJECTIVE

To further characterize the clinical features, etiologic associations, laboratory findings, and treatment of pernio.

PATIENTS AND METHODS

This is a retrospective review of patients with pernio seen at our institution between January 1, 2000, and December 31, 2011.

RESULTS

Of 104 patients with pernio (mean age at diagnosis, 38.3 years), 82 (79%) were women. Pernio affected the toes in 85 patients (82%) and the fingers in 31 (30%). Thirty-eight patients (37%) had at least 1 abnormal laboratory test result, and test results were positive for cold agglutinins in 11 (55%) of 20 tested patients. Results were negative for cryoglobulins in all tested patients (n=53). Four patients (4%) had connective tissue disease (nonlupus) associated with pernio; 3 patients (3%) had an associated hematologic malignant disease. Conservative treatments (eg, warming, drying, and smoking cessation) provided complete response in 23 (82%) of 28 patients with follow-up data.

CONCLUSION

To our knowledge, this study represents one of the largest single-center case series of pernio to date. Most of the patients did not have an underlying systemic association with pernio, although a few patients had pernio in association with connective tissue disease or hematologic malignant disease.

Perniosis in a long-distance cyclist crossing Mongolia

We report a case of severe perniosis in a long-distance cyclist. This case demonstrates the importance of identifying those at risk of cold-related injuries who are about to embark on extensive travel in cold environments.