Direct immunofluorescence testing in vasculitis-A single institution experience with Henoch-Schönlein purpura

Navigating the initial diagnosis and management of adult IgA vasculitis: A review

Background

IgA vasculitis in adults has not been thoroughly studied. This has left a practice gap related to the management and follow-up of a population that is at an increased risk of comorbidities and potentially poor outcomes. For this reason, it is important to synthesize evidence from the current literature because this can help direct the movement for more robust studies to clarify best practice recommendations.

Objective

We sought to create a narrative review for the practicing dermatologist when diagnosing and leading the care of IgA vasculitis in adult patients.

Methods

A broad literature search was performed with a focus on articles that were published after the introduction of the most updated European Alliance of Associations for Rheumatology/Pediatric Rheumatology International Trials Organization/Pediatric Rheumatology European Society criteria.

Results

The characteristics and management guidelines for IgA vasculitis in adults have been refined, although more rigorous studies are needed to develop best practice recommendations.

Limitations

Because of the lack of sufficient randomized controlled trials on IgA vasculitis in adults, this narrative review is composed of mostly observational, descriptive studies.

Conclusion

Adults with IgA vasculitis are at an increased risk of complicated disease course, necessitating formal diagnostic assessment and clear-cut follow-up recommendations to manage and prevent poor health outcomes related to various comorbidities.

Assessment of Clinical and Laboratory Use of the Cutaneous Direct Immunofluorescence Assay

Importance

Dermatologists submit direct immunofluorescence (DIF) biopsies on a daily basis, using an assay detecting immunoreactant deposition with a panel that has traditionally comprised immunoglobulin (Ig) G, IgA, IgM, C3, and fibrin, with or without albumin antibodies.

Objectives

To evaluate and compare the frequency of immunoreactants in DIF biopsies submitted over an 8-year period and assess use by dermatologists based on clinical impression.

Design, Setting, and Participants

A quality improvement study was conducted in a community outreach reference laboratory associated with a large academic medical center. Results of 2050 consecutive DIF skin biopsies submitted to the laboratory between April 1, 2012, and June 12, 2020, were analyzed by final pathologic diagnosis and antibody subtype positivity, in comparison with clinical impression. Biopsies in which the submitting physician had not performed the biopsy were excluded.

Main Outcomes and Measures

Histopathologic findings and the results of DIF biopsies using the standard 6-antibody panel were evaluated in correlation with the submitted clinical diagnosis to assess immunoreactivity of the assay.

Results

Of 2050 DIF biopsies submitted, 367 (17.9%) were positive; IgG, IgA, and C3 alone identified all primary immunobullous disease cases (pemphigoid, pemphigus, linear IgA, and dermatitis herpetiformis), and IgA, C3, and fibrin antibodies alone identified all vasculitis cases. A panel of IgG, IgA, IgM, and fibrin identified all cases of lupus erythematosus. DIF results were positive in less than half of cases of hematoxylin and eosin biopsy-confirmed lupus erythematosus (23 of 47 [49%]). A total of 247 biopsies were submitted for clinical diagnoses not optimally supported on DIF: lichen planus, porphyria, and connective tissue disease.

Conclusions and Relevance

The findings of this study suggest that there is a knowledge gap among dermatologists relating to the opportunity for high-value, cost-conscious use of DIF. The practice of reflexive antibody testing using a 6-antibody panel for all DIF biopsies is likely unnecessary. DIF protocols tailored to the clinical diagnosis may enhance cost-effectiveness without loss of test sensitivity or specificity.

Practical Direct Immunofluorescence

Direct immunofluorescence (DIF) remains a valuable tool that may be underused because of perceived challenges in the interpretation, limitations, and processing of DIF specimens. The aim of this review is to provide a practical guide for appropriately incorporating DIF in a variety of clinical diseases, such as autoimmune blistering disorders. In vasculitis, the role of DIF continues to evolve, particularly in the setting of IgA vasculitis. Although typically not indicated for the workup of connective tissue disease, DIF may be helpful in cases with negative serologies, nondiagnostic histologic findings, or scarring alopecia. Practical pearls for biopsy technique, specimen handling, and storage are also discussed.

Clostridioides difficile infection in a patient with immunoglobulin A vasculitis: a triggering factor or a rare complication of the disease? A case-based review

IgA vasculitis, formerly known as Henoch-Schonlein purpura (HSP), is the most common form of systemic vasculitis in children and is characterized by inflammation of the small vessels with typical deposition of IgA immune complexes. It is a leukocytoclastic type of vasculitis and is characterized by a tetrad of clinical manifestations: non-thrombocytopenia or coagulopathy-induced palpable purpura, arthritis, or arthralgia, gastrointestinal, and renal involvement. The exact cause of IgA vasculitis is not known yet, although infections, vaccinations and insect bites have been implicated in the appearance of the disease. The main risk factors for Clostridioides difficile infection (CDI) are previous CDI, age > 65 years old, pharmacologic agents (antibiotics, PPIs, histamine-2 receptor antagonists, glucocorticoids, and chemotherapy), prior hospitalization, the presence of co-morbidities, especially inflammatory bowel diseases and chronic kidney disease (CKD) and immunosuppression. Oral vancomycin or fidaxomicin are the gold standard of the therapy, with metronidazole being an alternative choice. The purpose of this study was to describe a case of IgA vasculitis and Clostridioides difficile infection to see whether there is any association between the two distinct clinical entities. Herein, we describe a 17-year old patient with IgA vasculitis and bloody diarrhea due to Clostridioides difficile infection and we discuss the co-existence of these two pathological conditions. The patient presented to the hospital with diffuse abdominal pain, nausea, vomiting, and two episodes of bloody diarrhea. Stools tested positive for Clostridioides difficile toxins, while he remained afebrile with hs-CRP = 1.5 mg/dL (normal range < 0.5 mg/dL). Direct immunofluorescence from the extremities' purplish eruption showed leukocytoclastic vasculitis with IgA deposition. Whether co-existence of the two above-mentioned distinct clinical entities is just a co-incidence or CDI is a triggering factor for IgA vasculitis remains to be elucidated in future large-scale studies.