Role of Direct Immunofluorescence in Cutaneous Small-Vessel Vasculitis: Experience From a Tertiary Center

Diagnostic utility of direct immunofluorescence test panels for cutaneous vasculitis: A scoping review

BACKGROUND

Due to the immune-mediated nature of non-infectious cutaneous vasculitis, skin biopsy specimens are often submitted for direct immunofluorescence (DIF) testing when vasculitis is considered clinically. However, evidence regarding the clinical value of DIF has not been rigorously appraised.

OBJECTIVE

In this scoping review, we aimed to systematically evaluate the peer-reviewed literature on the utility of DIF in vasculitis to assist with the development of appropriate use criteria by the American Society of Dermatopathology.

METHODS

Two electronic databases were searched for articles on DIF and vasculitis (January 1975-October 2023). Relevant case series involving more than or equal to three patients, published in English, and with full-text availability were included. Additional articles were identified manually via reference review. Due to study heterogeneity, findings were analyzed descriptively.

RESULTS

Of 255 articles identified, 61 met the inclusion criteria. Cumulatively representing over 1000 DIF specimens, several studies estimated DIF sensitivity to be 75%. While vascular immunoglobulin A (IgA) deposits on DIF were associated with renal disease, other systemic associations were inconsistent. Vascular IgG deposition may be overrepresented in ANCA-associated vasculitis. Granular vascular and epidermal basement membrane zone Ig deposition differentiated hypocomplementemic from normocomplementemic urticarial vasculitis. Few studies have assessed the added value of DIF over routine microscopy alone in vasculitis.

CONCLUSIONS

This scoping review discovered that DIF testing for vasculitis has been performed not only for diagnostic confirmation of vasculitis but also for disease subtype classification and prediction of systemic associations. Future studies on test sensitivity of DIF compared to that of histopathology are needed.

PUPAID: A R + ImageJ pipeline for thorough and semi-automated processing and analysis of multi-channel immunofluorescence data

PUPAID is a workflow written in R + ImageJ languages which is dedicated to the semi-automated processing and analysis of multi-channel immunofluorescence data. The workflow is designed to extract fluorescence signals within automatically-segmented cells, defined here as Areas of Interest (AOI), on whole multi-layer slides (or eventually cropped sections of them), defined here as Regions of Interest (ROI), in a simple and understandable yet thorough manner. The included (but facultative) R Shiny-based interactive application makes PUPAID also suitable for scientists who are not fluent with R programming. Furthermore, we show that PUPAID identifies significantly more cells, especially in high-density regions, as compared to already published state-of-the-art methods such as StarDist or Cellpose. For extended possibilities and downstream compatibility, single cell information is exported as FCS files (the standardized file format for single cell-based cytometry data) in order to be openable using any third-party cytometry analysis software or any analysis workflow which takes FCS files as input.

Direct immunofluorescence demystified: Essential insights and recent advances for dermatologists

Direct immunofluorescence (DIF) is widely used in dermatopathology for the diagnosis of autoimmune blistering diseases (AIBDs), cutaneous vasculitis, and connective tissue disorders. Although it is easy and useful to perform, it needs technical expertise and experience for proper interpretation. The yield of DIF depends on multiple factors including the adequacy, transportation, storage, processing, and interpretation of the biopsy specimen. Effective collaboration between the dermatologist and dermatopathologist along with meticulous clinico-pathological correlation is crucial for accurately interpreting DIF in the appropriate clinical context. In this narrative review of DIF in dermatology, we discuss the indications of DIF, recent updates on the selection of optimum biopsy sites, basic techniques of DIF including the classical transport medium and its alternatives, processing and staining technique, patterns in various diseases, advancements such as serration pattern analysis, and latest recommendations on the use of DIF in cutaneous disorders.

Case report of streptococcal infection as a potential precipitating factor in cutaneous polyarteritis nodosa in pediatric patients

Key Clinical Message

This pediatric case report underscores the importance of maintaining a high clinical suspicion for polyarteritis nodosa (PAN) in patients presenting with atypical features, such as migratory arthritis and subcutaneous nodules. Importantly, it highlights the focus on the potential relationship between streptococcal infection and cutaneous PAN. Early recognition and prompt, aggressive treatment is critical, as PAN can be a life-threatening condition if left unmanaged. This case emphasizes the need for a multidisciplinary approach to effectively identify and manage this rare vasculitis disorder in the pediatric population.

Abstract

Polyarteritis nodosa (PAN) is a rare and life-threatening vasculitis with diverse clinical presentations, posing a diagnostic challenge. Early recognition and prompt intervention are crucial to prevent organ damage. We present the case of an 8-year-old boy who exhibited atypical symptoms including migratory arthritis, myalgia, digital discoloration and ischemic changes, and subcutaneous nodules. Initial concerns for septic arthritis were ruled out. A comprehensive evaluation revealed elevated inflammatory markers and a confirmatory skin biopsy demonstrating active leukocytoclastic vasculitis, are highly suggestive of a diagnosis of PAN. Notably, elevated ASO titers suggested a possible concurrent streptococcal infection. The aggressive treatment approach with high-dose aspirin, steroids, methotrexate, and tocilizumab is justified given the severity of the patient's symptoms and the nature of the disease process. This case underscores the importance of considering PAN in the differential diagnosis for children presenting with atypical features. Early diagnosis and prompt intervention, including addressing potential infectious triggers, are crucial for optimal outcomes in pediatric PAN.

Systemic disease in leukocytoclastic vasculitis: a focus on direct immunofluorescence findings

BACKGROUND

Direct immunofluorescence (DIF) panels are usually ordered for clinically suspected cutaneous vasculitis, but their positivity rate is variable, and their prognostic significance is not clear to date.

OBJECTIVE

The study aims to investigate the systemic involvement rate in leukocytoclastic vasculitis (LCV) patients and the potential clinical and laboratory associations with systemic involvement, including DIF findings.

METHODS

A retrospective study of patients with histopathologically proven cutaneous LCV examined in the dermatology department between 2013 and 2017 was performed.

RESULTS

Of the 81 patients (mean age, 50.6 years), 42 (52%) were male. The mean time between the appearance of skin lesions and biopsy was 23.1 days, ranging from 2 to 180 days. DIF showed overall positivity of 90.1%, and C3 was the most frequent immunoreactant (82.7%). Any kind of extracutaneous involvement was present in 47 (58%) of patients, with renal involvement being the most frequent (53.1%), followed by articular (18.5%) and gastrointestinal (11.1%) involvement. The presence of renal disease was associated with the detection of IgG in the lesional skin (p = 0.017), and with the absence of IgM in the lesional skin (p = 0.032). There was a significant association between C3 deposition and joint involvement (p = 0.05).

STUDY LIMITATIONS

This is a single-center study with a retrospective design.

CONCLUSION

DIF seems to be a useful ancillary diagnostic tool in the evaluation of cutaneous vasculitis, but the relationship between DIF findings and systemic involvement needs to be further elucidated due to contradictory data in the current literature.

Cutaneous vasculitis: Lessons from COVID-19 and COVID-19 vaccination

Cutaneous vasculitis (CV) is an inflammatory skin-limited vascular disease affecting the dermal and/or hypodermal vessel wall. From the pathogenetic point of view, idiopathic forms are described as well as the induction from various triggers, such as drugs, infections, and vaccines. Following SARS-CoV-2 pandemic outbreak, cases of CV induced by both COVID-19 and COVID-19 vaccinations have been reported in literature. The aim of our work was to collect multiple cases available in the literature and analyze the frequency of the different forms of induced vasculitis, as well as their histological and immunopathological features. Although rare, CV induced by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and vaccines may provide interesting insights into the pathogenesis of these inflammatory processes that may in the future be useful to understand the mechanisms underlying cutaneous and systemic vasculitis.

A Cross-Sectional Study to Correlate Serum Complement C3 and C4 Levels With Clinical and Pathological Severity in Cutaneous Small-Vessel Vasculitis

Introduction

The role of serum C3 and C4 levels as a marker of disease activity in cutaneous small-vessel vasculitis (CSVV) has been sparsely studied, especially in India. The primary objective was to determine the correlation between clinico-histopathological severity and serum C3 and C4 levels in CSVV. The secondary objective was to determine the association between direct immunofluorescence (DIF) findings and serum C3 and C4 levels and clinico-histopathological findings.

Method

This prospective cross-sectional study included all the clinically diagnosed cases of CSVV that satisfied the pathological criteria for CSVV. A clinical disease activity grade and a histopathological severity grade were calculated in all patients (N=50).

Results

Serum C3 and C4 levels (n=44) were diminished in 4.5% of cases. There was no significant correlation between the serum C3 and C4 levels and the clinical and histopathological severity. DIF was positive in 60.0% of cases (n=45), and IgA was the predominant immune deposit (46.7%). No significant association was detected between the DIF findings and the serum C3 and C4 levels, histopathological severity, and clinical disease activity grade. Positive DIF findings were significantly associated with palpable purpura and cutaneous necrosis. A significant association was detected between gastrointestinal involvement and IgA positivity.

Conclusion

In CSVV, serum C3 and C4 may not be used as markers of disease severity, and a positive DIF finding may indicate an underlying gastrointestinal involvement.

Urticarial vasculitis: Clinical and laboratory findings with a particular emphasis on differential diagnosis

Urticarial vasculitis (UV) is a rare cutaneous vasculitis of small vessels characterized by recurrent episodes of wheal-like lesions that tend to last more than 24 hours, healing with a residual ecchymotic postinflammatory hyperpigmentation. The histopathologic pattern of UV is that of leukocytoclastic vasculitis, consisting of fibrinoid necrosis of dermal vessels' walls and neutrophil-rich perivascular inflammatory infiltrates. Although its etiopahogenesis remains still undefined, UV is now regarded as an immune complex-driven disease with activation of the complement cascade, leading to exaggerated production of anaphylatoxins that are responsible for neutrophil recruitment and activation. This condition can be categorized into 2 main entities according to serum complement levels: normocomplementemic UV and hypocomplementemic UV, the latter being associated with circulating anti-C1q autoantibodies and possible extracutaneous manifestations. Systemic multiorgan involvement may be seen particularly in syndromic hypocomplementemic UV, also known as McDuffie syndrome. This review summarizes the clinicopathological and laboratory features as well as the underlying pathophysiological mechanisms of UV. A focus on its main differential diagnoses is provided, that is, chronic spontaneous urticaria, bullous pemphigoid, IgA (Henoch-Schönlein purpura) and IgM/IgG immune complex vasculitis, lupus erythematous tumidus, Wells syndrome, erythema multiforme, cutaneous mastocytosis, cryopyrin-associated periodic syndromes, and coronavirus disease 2019-associated and anti-severe acute respiratory syndrome coronavirus 2-vaccine-associated urticarial eruptions.

Urticarial vasculitis: A potential signpost for multisystem inflammatory syndrome in children

Multisystem inflammatory syndrome in children (MIS-C) is a rare and serious complication of Sars-Cov-2 infection. Dermatologic manifestations are present in the majority of patients. Skin lesions found in children with MIS-C are classified into four categories: morbilliform, reticulated, scarlatiniform, and urticarial lesions. Clinicopathologic characterization within these categories is limited. Thus, we present a clear example of an urticarial lesion in the context of MIS-C with well-documented clinicopathologic phenomena. A previously healthy 16-year-old female presented with 3 weeks of an itchy, burning rash initially presenting on her right forearm (and lasting greater than 24 hours without migration) before spreading diffusely. She also reported fever, cough, myalgias, nausea, and vomiting of 4 weeks' duration. Physical examination revealed an edematous, maculopapular, nonblanching, erythematous rash covering the patient's upper extremities, abdomen, back, anterior thighs, and face. The patient tested positive for COVID-19. A low-grade leukocytoclastic vasculitis was noted along with intraluminal fibrin and rare microthrombi in vessels of the mid to deep dermis. The patient was diagnosed with MIS-C and urticarial vasculitis. She was treated with steroids and naproxen for subsequent MIS-C flares. Dapsone treatment was started for the urticarial vasculitis.

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.

Immunoglobulin-A Vasculitis With Renal Involvement in a Patient With COVID-19: A Case Report and Review of Acute Kidney Injury Related to SARS-CoV-2

Rationale:

Acute kidney injury is a common complication of COVID-19 and is associated with significantly increased mortality. The most frequent renal biopsy finding with SARS-CoV-2 infection is acute tubular injury; however, new onset glomerular diseases have been reported. The development of persistent urinary abnormalities in patients with COVID-19 should prompt consideration for renal biopsy to rule out glomerulonephritis.

Presenting Concerns:

A 30-year-old man with no prior medical history presented to the emergency department with symptoms of COVID-19 and new onset painful purpuric rash, arthralgia, and abdominal pain. SARS-CoV-2 infection was confirmed with nucleic acid testing and laboratory investigations revealed preserved renal function with dysmorphic hematuria and nephrotic range proteinuria.

Diagnosis:

A skin biopsy of the purpuric rash was performed, which demonstrated leukocytoclastic vasculitis. Renal biopsy revealed focally crescentic and segmentally necrotizing IgA nephropathy. Overall, given the clinical syndrome of glomerulonephritis with purpuric rash, arthralgia, and abdominal pain, the presentation is most in keeping with a diagnosis of IgA vasculitis in the setting of COVID-19.

Interventions:

The patient was treated conservatively for COVID-19 in the community. A 7-day course of prednisone was started for the vasculitic rash. IgA nephropathy was managed conservatively with blood pressure control and RAAS blockade with losartan.

Outcomes:

With conservative management, the patient’s COVID-19 symptoms resolved completely and he did not require hospital admission. Following prednisone therapy, the patient’s rash, arthralgia, and abdominal pain improved. However, despite resolution of COVID-19, hematuria and proteinuria persisted. With the initiation of RAAS blockade, renal function remained stable and proteinuria improved dramatically at 6 weeks.

Novel Findings:

De novo glomerulonephritis is a renal manifestation of SARS-CoV-2 infection beyond acute tubular injury. IgA vasculitis appears to be a rare complication of COVID-19.

Atypical Bacterial Pathogens and Small-Vessel Leukocytoclastic Vasculitis of the Skin in Children: Systematic Literature Review

Leukocytoclastic small-vessel vasculitis of the skin (with or without systemic involvement) is often preceded by infections such as common cold, tonsillopharyngitis, or otitis media. Our purpose was to document pediatric (≤18 years) cases preceded by a symptomatic disease caused by an atypical bacterial pathogen. We performed a literature search following the Preferred Reporting of Systematic Reviews and Meta-Analyses guidelines. We retained 19 reports including 22 cases (13 females and 9 males, 1.0 to 17, median 6.3 years of age) associated with a Mycoplasma pneumoniae infection. We did not find any case linked to Chlamydophila pneumoniae, Chlamydophila psittaci, Coxiella burnetii, Francisella tularensis, or Legionella pneumophila. Patients with a systemic vasculitis (N = 14) and with a skin-limited (N = 8) vasculitis did not significantly differ with respect to gender and age. The time to recovery was ≤12 weeks in all patients with this information. In conclusion, a cutaneous small-vessel vasculitis with or without systemic involvement may occur in childhood after an infection caused by the atypical bacterial pathogen Mycoplasma pneumoniae. The clinical picture and the course of cases preceded by recognized triggers and by this atypical pathogen are indistinguishable.

[Cutaneous vasculitis and vasculopathy : Differential diagnosis in biopsies of the lower extremities]

The skin is one of the most frequently involved organs in primary systemic and secondary vasculitis; moreover, a vasculitis can occur as single organ vasculitis, limited to the skin. For most types of vasculitis, the lower extremities constitute common sites with clinical symptoms of palpable purpura, nodules, and ulcers. In histopathology of cutaneous vasculitis, it is of utmost importance to correctly identify the vessel types involved and to discriminate between vasculitic vessel damage, unspecific reactive vessel changes, vascular occlusive diseases, noninflammatory purpura, or perivascular infiltrates due to other inflammatory skin diseases. Small-vessel vasculitis is the most frequent type of cutaneous vasculitis; during florid phases, a dermal leukocytoclastic vasculitis is found regardless of etiology. Additional extravascular changes may give etiological clues, however, a correlation with the clinical picture, radiology, and serology is essential. The biopsy type and technique need to be adjusted to the suspected diagnosis and site of the vessels involved. Polyarteritis nodosa and nodular vasculitis can be diagnosed only in biopsies with sufficient subcutaneous tissue. Especially in cutaneous ulcers, a lateral rim of vital skin and subcutaneous tissue is indispensable for a correct diagnosis. Large-vessel vasculitis is not found in skin biopsies of the lower extremities.

Drug-induced cutaneous vasculitis and anticoagulant-related cutaneous adverse reactions: insights in pathogenesis, clinical presentation, and treatment

Drug-induced vasculitis and anticoagulant-related skin reactions are commonly encountered in the inpatient and outpatient settings. The spectrum of clinical presentation is broad and ranges from focal, skin-limited disease, to more extensive cutaneous and soft tissue necrosis, to potentially fatal systemic involvement. The prompt recognition of these adverse events can have a significant impact on patient morbidity and mortality. We highlight the key features of the clinical presentation with an emphasis on primary lesion morphology, distribution, and epidemiology of purpuric drug reactions. The proposed pathophysiology, histologic findings, and therapeutic interventions of these potentially life-threatening diseases are discussed.

Ex vivo confocal laser scanning microscopy: An innovative method for direct immunofluorescence of cutaneous vasculitis

Ex vivo confocal laser scanning microscopy (ex vivo CLSM) offers an innovative diagnostic approach through vertical scanning of skin samples with a resolution close to conventional histology. In addition, it enables fluorescence detection in tissues. We aimed to assess the applicability of ex vivo CLSM in the detection of vascular immune complexes in cutaneous vasculitis and to compare its diagnostic accuracy with direct immunofluorescence (DIF) microscopy. Eighty-two sections of 49 vasculitis patients with relevant DIF microscopy findings were examined using ex vivo CLSM following staining with fluorescent-labeled IgG, IgM, IgA, C3 and fibrinogen antibodies. DIF microscopy showed immunoreactivity of vessels with IgG, IgM, IgA, C3 and Fibrinogen in 2.0%, 49.9%, 12.2%, 59.2% and 44.9% of the patients, respectively. Ex vivo CLSM detected positive vessels with the same antibodies in 2.0%, 38.8%, 8.2%, 42.9% and 36.7% of the patients, respectively. The detection rate of positive superficial dermal vessels was significantly higher in DIF microscopy as compared to ex vivo CLSM (P < .05). Whereas, ex vivo CLSM identified positive deep dermal vessels more frequently compared to DIF microscopy. In conclusion, ex vivo CLSM could identify specific binding of the antibodies in vessels and showed a comparable performance to conventional DIF microscopy in diagnosing vasculitis.

Case of both rivaroxaban- and dabigatran-induced leukocytoclastic vasculitis, during management of pulmonary thromboembolism

Leukocytoclastic vasculitis is a disorder characterized by neutrophilic inflammation that is predominantly limited to the superficial cutaneous postcapillary venules. This condition may be idiopathic or may have a defined cause. Rivaroxaban and dabigatran have been widely used as warfarin alternatives, because of their efficacy and safety. In this case report, we describe a case of leukocytoclastic vasculitis induced by both rivaroxaban- and dabigatran-, which developed during the management of pulmonary thromboembolism.

Treatment of urticarial vasculitis: A systematic review

Urticarial vasculitis (UV) is a difficult-to-treat condition characterized by long-lasting urticarial rashes and histopathologic findings of leukocytoclastic vasculitis. Treatment is dictated by the severity of skin and systemic involvement and the underlying systemic disease. This is a comprehensive systematic review of the efficacy of current UV treatment options. We searched for relevant studies in 7 databases, including MEDLINE, Scopus, and Web of Science. In total, 261 eligible studies and 789 unique patients with UV were included in the systematic review. Most patients with UV are adult women with chronic (≥6 weeks) and systemic disease. UV is mostly idiopathic but can be associated with drugs, malignancy, autoimmunity, and infections. It usually resolves with their withdrawal or cure. Corticosteroids are effective for the treatment of skin symptoms in more than 80% of patients with UV. However, their long-term administration can lead to potentially serious adverse effects. The addition of immunomodulatory or immunosuppressive agents often allows corticosteroid tapering and improves the efficacy of therapy. Biologicals, including omalizumab, as well as corticosteroids, cyclophosphamide, dapsone, mycophenolate mofetil, plasmapheresis, colchicine, hydroxychloroquine, intravenous immunoglobulin, nonsteroidal anti-inflammatory drugs, and cyclosporine, can be effective for both skin and systemic symptoms in patients with UV. H₁-antihistamines, montelukast, danazol, H₂-antihistamines, pentoxifylline, doxepin, and tranexamic acid are not effective in most patients with UV. As of yet, no drugs have been approved for UV, and management recommendations are based mostly on case reports and retrospective studies. Prospective studies investigating the effects of treatment on the signs and symptoms of UV are needed.