Reactive Granulomatous Dermatitis: A Review of Palisaded Neutrophilic and Granulomatous Dermatitis, Interstitial Granulomatous Dermatitis, Interstitial Granulomatous Drug Reaction, and a Proposed Reclassification

Palisaded Neutrophilic Granulomatous Dermatitis, Bowel-Associated Dermatosis-Arthritis Syndrome, and Rheumatoid Neutrophilic Dermatitis

Neutrophilic dermatosis is a heterogeneous group of inflammatory skin diseases characterized by the presence of a sterile neutrophilic infiltrate on histopathology. Three specific types of neutrophilic dermatoses are reviewed in this article: palisaded neutrophilic granulomatous dermatitis, bowel-associated dermatosis-arthritis syndrome, and rheumatoid neutrophilic dermatitis. The authors review the literature and highlight the clinical and histopathological features, disease pathogenesis, and the association of these conditions with various systemic diseases such as rheumatoid arthritis, inflammatory bowel disease, and others. A multidisciplinary approach is necessary for the diagnosis and management of these inflammatory skin conditions.

Quality of Life with Neutrophilic Dermatoses

Neutrophilic dermatoses (NDs) encompass a wide range of cutaneous and extracutaneous manifestations, many of which impair quality of life (QoL) and are difficult to treat. Although NDs are transient and mild, others are chronic, severely debilitating conditions with profound impacts on QoL, including pain, mental health, occupational limitations, and sexual health implications. Current literature lacks attention to these unique care challenges to the ND patient population. The authors aim to summarize what is currently known about QoL in NDs and identify which diseases would benefit from additional research and disease-specific QoL assessment.

Annular Erythematous Eruption in a Pediatric Patient

An 11-year-old girl presented in autumn with an asymptomatic rash on her arms, face, and legs of a 3-week duration. What is your diagnosis?

Reactive Granulomatous Dermatitis: A Descriptive Study of 10 Patients

BACKGROUND

Reactive granulomatous dermatitis (RGD) is a rare and misunderstood skin disorder. It includes interstitial granulomatous dermatitis and palisaded neutrophilic and granulomatous dermatitis: 2 entities of the same spectrum. Multiple associations are described with RGD in the literature, including autoimmune diseases, malignancy, and drugs.

OBJECTIVE

To report and describe the suspected associations with RGD at the time of diagnosis and in the following year.

METHODS

We retrieved and described cases of RGD confirmed by skin biopsy and clinicopathologic correlation. All patients were evaluated in the Centre Hospitalier Universitaire de Québec-Université Laval between January 2000 and December 2020. Collected data include the systemic diseases (autoimmune disease, malignancy) and suspected drugs, in addition to the clinical presentation and prescribed treatments.

RESULTS

Out of the 10 patients with RGD, 7 patients were known to have an autoimmune disease at the time of diagnosis. They either had inflammatory arthritis (3/10) or inflammatory bowel disease (4/10). There was a clinical suspicion of a possible association with a tumor necrosis factor (TNF) inhibitor in 2 of these 7 patients. Among the 3 patients with idiopathic RGD at the time of diagnosis, 1 patient developed a high-grade B-cell lymphoma 6 months later. There was no new association identified in the following year for patients with a known autoimmune condition.

CONCLUSION

This descriptive study supports RGD and its previously described systemic associations, particularly autoimmune diseases, malignancy, and certain drugs (specifically TNF inhibitors). The majority of patients already had one of these associations identified at the time of histopathological diagnosis.

Clinical, Histopathological and Molecular Spectrum of Cutaneous Lesions in Myelodysplastic Syndrome and Myeloproliferative Neoplasms (MDS/MPN): An Integrative Review

Myeloid neoplasms and acute leukemias include different entities that have been recently re-classified taking into account molecular and clinicopathological features. The myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) category comprises a heterogeneous group of hybrid neoplastic myeloid diseases characterized by the co-occurrence of clinical and pathological features of both myelodysplastic and myeloproliferative neoplasms. The most frequent entity in this category is chronic myelomonocytic leukemia (CMML) which is, after acute myeloid leukemia (AML), the main myeloid disorder prone to develop cutaneous manifestations. Skin lesions associated with myelodysplastic and myeloproliferative neoplasms include a broad clinical, histopathological and molecular spectrum of lesions, poorly understood and without a clear-cut classification in the current medical literature. The aim of this review is to describe and classify the main clinical, histopathological and molecular patterns of cutaneous lesions in the setting of MDS/MPN in order to improve the diagnostic skills of the dermatologists, hematologists and pathologists who deal with these patients.

Reactive Granulomatous Dermatitis in a Child with Acute Lymphoblastic Leukemia

Reactive granulomatous dermatitis (RGD) is an umbrella term to describe a reaction pattern characterized by skin-colored to erythematous papules, plaques, and nodules although other morphologies have been described. RGD has rarely been reported in children, and in this report, we present the case of a 3-year-old girl with acute lymphoblastic leukemia (ALL) who presented with firm, tender nodules, and ulcerated plaques on her extremities. Histopathologic examination showed foci of dense granulomatous inflammatory infiltrates composed of histiocytes, neutrophils, and multinucleate giant cells. The constellation of clinical symptoms, negative infectious workup, and histopathology support the diagnosis of RGD.

Cutaneous Manifestations of Rheumatoid Arthritis: Diagnosis and Treatment

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disorder characterized by inflammatory arthritis and periarticular structural damage. Available evidence suggests that RA results from complex interactions between genetic susceptibility (e.g., HLA-DRB1), environmental factors (e.g., smoking), and immune dysregulation. Alongside joint-related symptoms, individuals with RA may also experience a wide array of skin issues, including the development of nodules, neutrophilic dermatoses, vasculitis, and vasculopathy. Treatment strategies for these manifestations vary but routinely involve corticosteroids, disease-modifying anti-rheumatic drugs, and biologics, with individualized approaches guided by disease severity. In this review, we provide comprehensive insights into the skin-related issues associated with RA, outlining their clinical characteristics and histopathological findings. Our aim is to facilitate early diagnosis and personalized treatment to improve the quality of life of affected individuals.

Immune checkpoint inhibitor-induced cutaneous toxicities: a review of histopathologic and clinical features

Immune checkpoint inhibitors (ICIs) represent an emerging treatment option for a variety of cancer types. Through inhibition of programmed cell death protein 1 (PD-1), programmed cell death ligand 1 (PD-L1), and/or cytotoxic lymphocyte-associated antigen-4 (CTLA-4), ICIs activate the host's immune system causing a heightened anti-tumor response. However, off-target effects of ICIs can result in numerous different immune-related cutaneous adverse events (irCAEs). Beyond impacting quality of life, irCAEs can lead to dose limitations or discontinuation of anti-cancer therapies. Correct diagnosis is necessary for expedient and appropriate management. Skin biopsies are often performed to increase diagnostic accuracy and guide clinical management. An extensive literature review was performed using the PubMed database to identify the reported clinical and histopathologic features of irCAEs. This comprehensive review primarily details the histopathologic features of various irCAEs reported to date. Clinical presentation and immunopathogenesis are also discussed in relation to histopathology.

A case of reactive granulomatous dermatitis associated with neonatal lupus erythematosus

Neonatal lupus erythematosus (NLE) is an uncommon disorder affecting approximately one out of 20 000 live births in the United States. Common manifestations of NLE include cutaneous eruptions and cardiac involvement. The typical rash of NLE most closely resembles the rash of subacute cutaneous lupus erythematosus both clinically and histopathologically. We present a case of reactive granulomatous dermatitis (RGD) associated with NLE in a 3-month-old male in whom the initial histopathology and immunohistochemistry were concerning for hematologic malignancy. RGD is a unifying term used to describe cutaneous granulomatous eruptions that occur in response to a variety of stimuli, including autoimmune connective tissue diseases. Our case demonstrates the range of histopathological findings that may be present in the setting of NLE.

Interstitial Granulomatous Dermatitis and Palisaded Neutrophilic Granulomatous Dermatitis: Retrospective Clinicopathological Analysis of 16 Cases

INTRODUCTION

Reactive granulomatous dermatitis (RGD) is a new entity, which is highly associated with systemic disorders. There is scarce data regarding interstitial granulomatous dermatitis (IGD) and palisaded neutrophilic granulomatous dermatitis (PNGD).

OBJECTIVES

We aimed to evaluate clinical and histopathological characteristics of IGD and PNGD as unified entities under the term of RGD.

METHODS

Observational, retrospective, single-center study of patients diagnosed with IGD and PNGD between 2012 and 2021 were included in the study.

RESULTS

Of 16 patients (14 females and 2 males) with RGD, 13 had IGD and 3 had PNGD with a mean age of 62.5 years. The most common clinical presentation was plaques 37.5% (N=6), followed by patches 25% (N=4). The most common localization of involvement was lower extremity 75% (N=12), followed by trunk and upper extremity. Multiple localization of involvement was determined in 75% (N=12) of patients. None of the patients had rope sign. Associated comorbidities such as autoimmune diseases and malignancies were detected in 68.7% (N=11) of patients. In majority of biopsies (87.5%; N=14), there were lymphohistiocytic cell infiltration. Other accompanying cells were scarce neutrophils 31.2% (N=5) and eosinophils 31.2% (N=5). All of the biopsies had interstitially located lymphohistiocytic cell infiltration surrounding with swollen and degenerated collagen. Palisaded pattern was determined in 18.7% (N=3) of patients and floating sign was seen in 18.7% (N=3) of biopsies.

CONCLUSIONS

RGD is a rare entity and most patients with RGD had associated disorders such as autoimmunity or malignancy. There is overlapping between IGD and PNGD, therefore supporting the usage of umbrella term as reactive granulomatous dermatitis is compatible with the literature.

Multiple Erythematous-Violaceous Patches and Plaques on the Left Upper Arm and Left Side of the Chest

A woman in her late 20s had multiple, slowly growing, infiltrated erythematous-violaceous patches and plaques with occasional slight pain extending from her left upper arm to the left side of her chest. What is your diagnosis?

Reactive granulomatous dermatitis as a clinically relevant and unifying term: a retrospective review of clinical features, associated systemic diseases, histopathology and treatment for a series of 65 patients at Mayo Clinic

BACKGROUND

Reactive granulomatous dermatitis (RGD) is an umbrella term used to describe interstitial granulomatous dermatitis (IGD), palisaded neutrophilic and granulomatous dermatitis (PNGD), and interstitial granulomatous drug eruption (IGDR).

OBJECTIVE

The aim of this study was to describe systemic associations of RGD, explore possible associations between histopathologic findings and systemic RGD associations and determine clinical relevance of RGD subtypes.

METHODS

We retrospectively studied clinical and histopathologic characteristics of patients with RGD from 1990 through 2020.

RESULTS

Of 65 patients with RGD (41 women, 24 men; median age at diagnosis, 62 years), 37 had IGD, 26 had PNGD, and 2 had IGDR. Fifty patients (76.9%) had an associated systemic condition; rheumatologic conditions were identified for 34 (52.3%) patients. The associated systemic condition occurred before RGD in approximately 75% of patients. Statistical analyses did not show significant associations between specific subtypes of RGD and systemic diseases or treatment response, and specific histopathologic findings were not predictive of an associated systemic disease.

CONCLUSIONS

Although most patients with RGD had an associated systemic condition, subtypes of RGD did not correlate with systemic associations, lending support to the use of the umbrella term RGD.

Annular drug eruptions

Cutaneous adverse drug reactions are undesirable cutaneous changes caused by medications. Drug eruptions can mimic a wide range of dermatoses that include exanthematous (morbilliform), urticarial, pustular, bullous, papulosquamous, or granulomatous lesions, and sometimes these eruptions may present with annular, polycyclic, or polymorphous configurations. The correct identification of a cutaneous drug eruption depends on a high index of suspicion, detailed medication exposure history, chronologic evaluation of the causal relationships between drug exposures and eruptions, and the exclusion of other infectious or idiopathic diseases. Most drug eruptions are annoying but self-limited, usually resolving after the withdrawal of the causative agents. Rarely, patients have severe cutaneous adverse reactions, such as Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms (DRESS), which are potentially lethal adverse drug reactions that involve the skin and mucous membranes and may also damage internal organs. Prompt recognition of the alarming signs of severe cutaneous adverse reactions and providing adequate treatment may thus be life-saving. We present the main clinical presentations, histopathology, possible implicated medications, and treatment of cutaneous adverse drug reactions that can present in annular configurations.

Interstitial Granulomatous Drug Reaction to Ustekinumab

Interstitial granulomatous drug reaction (IGDR) is a distinct inflammatory process that often presents as annular, violaceous plaques distributed on the extremities, proximal trunk, and intertriginous areas. The list of drugs implicated for inciting IGDR is growing, but most prominently includes ACE inhibitors, antihistamines, beta-blockers, antidepressants, and anticonvulsants. Ustekinumab is a human monoclonal antibody that targets inflammatory cytokines IL-12 and IL-23 and has been have shown to be effective in treating IGDR. However, we present a case that suggests ustekinumab can also act as an inciting agent for IGDR.

Unique Recognizable Histopathologic Variant of Palisaded Neutrophilic and Granulomatous Dermatitis that Is Associated With SRSF2-Mutated Chronic Myelomonocytic Leukemia: Case Report and Review of the Literature

ABSTRACT

Palisaded neutrophilic and granulomatous dermatitis (PNGD) represents a cutaneous histopathologic reaction spectrum associated with several underlying disorders. Few cases of PNGD have been associated with chronic myelomonocytic leukemia (CMML), a malignant hematopoietic disorder with features in between those of a myeloproliferative neoplasm and myelodysplastic syndrome. We present a patient with a generalized papular skin reaction involving the neck, chest, and shoulders with histomorphological features on the spectrum of PNGD. Subsequent laboratory workup demonstrated a persistent mild monocytosis, raising concern for CMML. The diagnosis was ultimately confirmed with a bone marrow biopsy and associated mutational analysis through next-generation sequencing which identified deleterious variants in SRSF2, IDH2, and ASXL1. The findings in this case strengthen the previously made association between PNGD and SRSF2-mutated CMML and may help better define a unique recognizable clinical-histopathological-molecular subtype for dermatopathologists.

Non-Infectious Granulomatous Dermatoses: A Pathologist's Perspective

Granulomatous dermatitis (GD) is one of the commonest tissue reaction patterns encountered in dermatopathology practice. Granulomatous inflammation in the skin can be seen in a wide range of conditions, thus, granulomatous dermatitis always poses significant challenge even to the astute dermatologists and dermatopathologists. Broadly, granulomatous dermatitis is divided into two groups-infectious and non-infectious, the prevalence of both highly variable and show overlapping pathology. However, there are subtle histological clues, which when combined with clinical features, help to narrow down the differential diagnosis. Thus, a good Clinicopathological correlation (CPC) along with histochemical stains, culture and ancillary techniques including molecular studies are required for arriving at a definite diagnosis. In this review, we shall discuss the histological clues to diagnose non-infectious granulomatous dermatitis (NIGD) and their differential diagnoses.

Symmetric drug-related intertriginous and flexural exanthema: Clinicopathologic study of 19 cases and review of literature

BACKGROUND

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a cutaneous drug reaction characterized by gluteal/anogenital erythema and symmetric involvement of other intertriginous location(s) without systemic signs. Clinicopathologic characterization has been limited to case reports and small series. We describe 19 new cases and review the literature to better define the clinical and histopathologic spectrum of SDRIFE.

METHODS

Pathology archives were searched for "SDRIFE" and "baboon syndrome." Cases meeting clinical criteria were included. Clinical and histopathologic features were recorded. Previous reports of SDRIFE with histopathologic descriptions were reviewed.

RESULTS

Nineteen new cases were included, over half triggered by antibiotics. Six new causative medications were identified. Median onset was 7 days. Typical lesions were erythematous plaques or papules with or without scale. The most common histopathologic finding was superficial perivascular lymphocytic infiltrate followed by dermal eosinophils, spongiosis, and orthokeratosis. Basal vacuolization and apoptotic keratinocytes were less common. Interstitial histiocytes were present in almost half of our cases. Other findings included atypical lymphocytes and "flame figure."

CONCLUSIONS

Appreciation of the range of inciting medications and clinicopathologic features in SDRIFE will improve recognition of this condition. Although many histopathologic features overlap with other common dermatitides, biopsy may assist in excluding key clinical mimics.

Granulomas in Dermatopathology: Principal Diagnoses - Part 2

Part 2 of this series on granulomatous diseases focuses on skin biopsy findings. Whereas the first part treated noninfectious conditions (metabolic disorders and tumors, among other conditions), this part mainly deals with various types of infectious disease along with other conditions seen fairly often by clinical dermatologists.

Palisaded neutrophilic and granulomatous dermatitis following a long-standing monoclonal gammopathy: A case report

Background

Palisaded neutrophilic granulomatous dermatitis is a rare inflammatory dermatosis with possible underlying systemic conditions including rheumatoid arthritis, autoimmune connective tissue disease, and malignancies.

Case Summary

We report a case of an 84-year-old man presenting with a 3-week eruption of asymptomatic annular plaques on his neck, which progressed to involve his back and legs. Skin biopsies confirmed a diagnosis of palisaded neutrophilic granulomatous dermatitis, and he was treated with prednisone. Full workup related to potential underlying causes of palisaded neutrophilic granulomatous dermatitis was completed.

Conclusion

Palisaded neutrophilic granulomatous dermatitis may precede the onset of underlying systemic conditions or occur concomitantly. Following the diagnosis, clinicians should perform a comprehensive focused history, physical examination, and laboratory investigation related to the associated underlying diseases.

Immune-Mediated Dermatoses in Patients with Haematological Malignancies: A Comprehensive Review

Haematological malignancies induce important alterations of the immune system, which account for the high frequency of autoimmune complications observed in patients. Cutaneous immune-mediated diseases associated with haematological malignancies encompass a heterogeneous group of dermatoses, including, among others, neutrophilic and eosinophilic dermatoses, autoantibody-mediated skin diseases, vasculitis and granulomatous dermatoses. Some of these diseases, such as paraneoplastic pemphigus, are associated with an increased risk of death; others, such as eosinophilic dermatoses of haematological malignancies, run a benign clinical course but portend a significant negative impairment on a patient’s quality of life. In rare cases, the skin eruption reflects immunological alterations associated with an unfavourable prognosis of the associated haematological disorder. Therapeutic management of immune-mediated skin diseases in patients with haematological malignancies is often challenging. Systemic corticosteroids and immunosuppressive drugs are considered frontline therapies but may considerably augment the risk of serious infections. Indeed, developing a specific targeted therapeutic approach is of crucial importance for this particularly fragile patient population. This review provides an up-to-date overview on the immune-mediated skin diseases most frequently encountered by patients with onco-haematological disorders, discussing new pathogenic advances and therapeutic options on the horizon.

Reactive granulomatous dermatitis as a histological pattern including manifestations of interstitial granulomatous dermatitis and palisaded neutrophilic and granulomatous dermatitis: a study of 52 patients

BACKGROUND

Confusion exists regarding interstitial granulomatous dermatitis (IGD) and palisaded neutrophilic and granulomatous dermatitis (PNGD).

OBJECTIVE

To determine whether IGD and PNGD are two different entities, or whether they must be considered as two subtypes of the same reactive pattern, and thus whether the unification of the nomenclature is necessary.

METHODS

Observational retrospective multicentre study of patients with IGD and PNGD evaluated between 1999 and 2019 and review of their clinical and histological features.

RESULTS

We identified 52 patients (38 women and 14 men). Clinical and histological findings of IGD were observed in 88.4% of cases. The most common cutaneous lesions were plaques/macules (IGD) or annular plaques and papules/nodules (PNGD), located mostly on the limbs and trunk. The rope sign was developed in two patients with IGD that associated autoimmune disorders. Similar associated comorbidities (75%) were found in both entities, mainly autoimmune diseases (53.8%). In IGD, the infiltrate was predominantly lympho-histiocytic. Neutrophilic infiltrates, karyorrhexis and skin lesions with limited clinical course were mainly associated with PNGD biopsies. In biopsies with a limited recurrent course, a predominant lymphocytic inflammatory infiltrate was found. Collagen degeneration was present in 75.9% of cases. The floating sign was observed only in IGD type patients (63%). Overlapping histological findings were found in one fourth of cases, especially between IGD and interstitial granuloma annulare. Interface dermatitis, apparently unrelated to drug intake, was observed in 4 cases of IGD.

CONCLUSION

We support the term reactive granulomatous dermatitis to unify both the clinical and histological findings of IGD and PNGD, and the overlapping between IGD and interstitial granuloma annulare. According to this, a spectrum of histological changes will be found depending on the clinical course of the skin lesions.

Granulomatous Dermatitis and Systemic Disease: An Association to Consider

Granuloma annulare (GA) and interstitial granulomatous dermatitis (IGD) are granulomatous dermatoses with variable clinical appearances. GA is associated with diabetes mellitus, metabolic syndrome, chronic infections, and malignancies, while two Japanese reports described unusual cases of interstitial-type GA in setting of Sjogren syndrome. IGD was associated with rheumatoid arthritis, systemic lupus erythematosus, and autoantibodies. We report a case series of six patients with GA or IGD. Half of the patients were diagnosed with Sjogren syndrome, while all of them presented ANA positivity and the majority reported arthralgia. In many cases, GA showed interstitial-type histology, arising challenges in differential diagnosis with IGD. The overlap of clinical and histological features of GA and IGD can be explained considering them as a broad disease spectrum, including also the other forms of reactive granulomatous dermatitis. These conditions should be considered as an indicator of possible systemic disorders or other immunological dyscrasias, for which patients must be screened. Sjogren syndrome may be associated to GA also in Caucasians.

Interstitial granulomatous dermatitis following tocilizumab, a paradoxical reaction?

Interstitial granulomatous dermatitis (IGD) is a rare dermatosis generally seen in the setting of rheumatic diseases, but also hematological disorders, internal malignances, infections, or drug induced. Herein, we report an exceptional case of an IGD with a clear chronological association with tocilizumab onset and cessation in a patient with adult-onset Still's disease. We review the granulomatous cutaneous reactions so far reported with this novel therapy: sarcoidosis, granuloma annulare, and IGD. Tocilizumab is a humanized anti-interleukin 6 receptor monoclonal antibody useful for the treatment of various systemic inflammatory disorders. Lately, it has found useful also for granulomatous diseases such as giant cell arteritis and even a promising response in IGD. Therefore, we believe our case adds the possibility of an IGD presenting as a paradoxical reaction.

Cutaneous drug eruptions including serum sickness-like reaction, symmetrical drug-related intertriginous and flexural exanthema, and drug-induced lupus

Cutaneous manifestations of drug reactions are common yet vary widely in their appearance and degree of internal organ involvement. Serum sickness--like reactions, symmetrical drug-related intertriginous and flexural exanthem, granulomatous drug eruption, pseudolymphoma, and drug-induced lupus are medication-induced conditions with dermatologic presentations. Many of the conditions discussed are relatively rare but nonetheless demand our attention and understanding. Some of the conditions presented may be more likely encountered in the hospital setting, as is the case with serum sickness-like reactions and drug-induced lupus, whereas others may present to outpatient clinic for diagnosis. Given the similarities in clinical history of patients presenting with these conditions, an understanding of the clinical presentation, pathophysiology, culprit medications, histologic appearance, and serologic characteristics is warranted to correctly diagnose and manage these uncommon adverse reactions. We also discuss how to differentiate some of these conditions from more serious mimickers, as in the case of pseudolymphoma drug reaction mimicking a true lymphoma and drug-induced lupus mimicking acute systemic lupus erythematosus.

Clinical and histologic presentation of pediatric reactive granulomatous dermatitis

OBJECTIVE

To characterize the clinical and histologic presentation of reactive granulomatous dermatitis (RGD) in the pediatric population.

METHODS

In this multicenter retrospective chart review, 7 pediatric patients with biopsy-proven RGD were identified. Photographs, histology reports, and clinical course were reviewed to discover patterns in demographics, comorbid conditions, autoimmune sequelae, drug exposures, infections, morphology, and histologic features.

RESULTS

Overall, 7 patients were included and analyzed. Most were female and Hispanic. All presented with a similar dermatologic phenotype previously described in the adult literature including macular erythema and annular, pink to violaceous, edematous papules and plaques, often involving proximal extremities and extensor joints. All biopsies demonstrated variable collagen alteration and a perivascular interstitial infiltrate of histiocytes with or without mucin. Neutrophils or karyorrhexic debris were present in 4/7 of the biopsies, and eosinophils were occasionally seen (2/7 cases). In all cases, RGD was associated with active SLE or led to a new diagnosis, and initiation of systemic treatment improved cutaneous disease.

CONCLUSIONS

Pediatric RGD was more common in female patients and ethnic minorities, and strongly associated with SLE. Clinical and histologic presentations were consistent across all cases with only minor variations, suggesting that recognition and confirmation might be expedited by familiarity with these dominant patterns. Diagnosis of RGD in pediatric patients should prompt screening for SLE.

In vivo cutaneous antinuclear antibody positivity in palisaded neutrophilic and granulomatous dermatitis

Palisaded neutrophilic and granulomatous dermatitis (PNGD) is commonly associated with underlying systemic inflammatory and neoplastic diseases, infections, and drug reactions. In vivo cutaneous antinuclear antibodies (ANA) have been described in skin biopsies from patients with known autoimmune disorders, but not previously reported in the setting of PNGD. We present two patients with systemic lupus erythematosus (SLE) and histopathologically confirmed PNGD. Direct immunofluorescence (DIF) studies revealed in vivo cutaneous ANA positivity in both patients. DIF findings in the skin mirrored serum autoantibody results. ANA positivity in skin specimens is reported as highly predictive of systemic connective tissue diseases (SCTD), although specific testing is not currently recommended as part of the laboratory work-up or diagnostic criteria for these disorders. In this case report, positive ANA results in skin biopsies of PNGD reflect the serological findings and clinical evidence of SLE in both patients. In vivo cutaneous ANA positivity is an interesting and supportive finding in PNGD in the setting of SCTD.

Interstitial granulomatous dermatitis and granulomatous arteritis in the setting of PD-1 inhibitor therapy for metastatic melanoma

Checkpoint inhibition has become an important target in the management of malignant melanoma. As anti-CTLA4 inhibitors and anti-PD1 antibodies are increasingly utilized, reports of immune-related adverse events (IRAEs) are becoming more frequent. Common noted cutaneous IRAEs are morbilliform, lichenoid, bullous, granulomatous, psoriasiform, and eczematous eruptions. We report a case of interstitial granulomatous dermatitis and granulomatous arteritis in the setting of nivolumab (anti-PD1) monotherapy for metastatic melanoma. There are many different causes for granulomatous vasculitis, such as herpes virus infection, lymphoproliferative disorders, systemic vasculitis, and inflammatory bowel disease. This report adds to the growing literature on granulomatous IRAEs due to checkpoint inhibition.

Clinical and pathological changes in the skin with granuloma annulare

Granuloma annulare (GA) is a dermatosis of unknown etiology, which has distinctive clinical and histological features. In this article, we present current information about the etiology, pathogenesis, clinical picture and pathomorphological signs of GA, as well as conduct differential diagnosis of GA with diseases that have a similar clinical and histological picture.