Does infection play a role in the pathogenesis of granuloma annulare?

Macrophage Biology in Human Granulomatous Skin Inflammation

Cutaneous granulomatoses represent a heterogeneous group of diseases, which are defined by macrophage infiltration in the skin. Skin granuloma can be formed in the context of infectious and non-infectious conditions. Recent technological advances have deepened our understanding of the pathophysiology of granulomatous skin inflammation, and they provide novel insights into human tissue macrophage biology at the site of ongoing disease. Here, we discuss findings on macrophage immune function and metabolism derived from three prototypic cutaneous granulomatoses: granuloma annulare, sarcoidosis, and leprosy.

Localized Versus Generalized Granuloma Annulare: A Retrospective Review of 407 Patients

BACKGROUND

Granuloma annulare has been linked to diabetes, dyslipidemia, thyroid disease, collagen vascular disease, malignancies, infectious hepatitis, and systemic infections. However, these associations have not been systematically investigated when categorized by its clinical variants.

OBJECTIVE

To evaluate disease associations of localized and generalized granuloma annulare.

METHODS

In total, 407 granuloma annulare patients from 1989 to 2019 were retrospectively reviewed, categorized by clinical variant (localized or generalized), age (pediatric or adult), and diagnostic method (clinical or histologic). Descriptive statistical analyses and multivariate logistic regression analysis were performed. Fisher's exact tests were conducted to produce unbiased probability values.

RESULTS

Overall, 75.2% of the study sample was female, 47.2% had dyslipidemia, 24.8% were diabetic, and 24.6% had thyroid disease. Dyslipidemia (OR 2.15, CI 1.95-2.35, P < .001), diabetes (OR 1.16, CI 1.01-1.31, P = .041), and histologic diagnosis (OR 2.08, CI 1.21-3.52, P = .007) were associated with increased risk of GGA compared to LGA. When stratified by adult versus pediatric cases, dyslipidemia and diagnostic method remained significant, but diabetes did not.

CONCLUSIONS

Evaluating granuloma annulare by its clinical variants may help to determine disease associations with each variant.

A Monocentric, Retrospective Analysis of 61 Patients with Generalized Granuloma Annulare

BACKGROUND

Granuloma annulare is a chronic noninfectious granulomatous skin condition with variable clinical presentations. Generalized granuloma annulare, defined as widespread disease with >10 skin lesions, accounts for 15% of all cases. Numerous associated diseases have been controversially discussed, most importantly diabetes mellitus, dyslipidemia, thyroid disease, malignancy and systemic infections.

OBJECTIVES

The objective of our study is to describe disease characteristics, treatment outcome and associated diseases in patients treated at the Department of Dermatology of the University Hospital Zurich during the last 20 years.

METHODS

The hospital database was searched for patients with generalized granuloma annulare in the last 20 years (January 1, 1998, to December 31, 2017). Overall, 61 patients, 14 males and 47 females, were included in our study. The mean age was 58 years at first consultation. The diagnosis was verified clinically and histologically.

RESULTS

Generalized granuloma annulare occurred at a mean age of 55 years, more commonly in females. Pruritus was absent in 51% of all patients. Metabolic diseases including diabetes mellitus, hypercholesterinemia and hypertriglyceridemia were present in 10.5, 8.2 and 4.9%, respectively. Thyroid disease was present in 9.8% and malignant disease in 23%, including colorectal cancer, lymphoproliferative disease, squamous cell carcinoma of the esophagus, basal cell carcinoma and gynecological malignancy. Therapy was initiated in 92%, while second- and third-line therapy was performed in 70 and 39%, respectively. Benefit during therapy (e.g., full and partial remission) was achieved in 39.3% during first-line, in 39.4% during second-line and in 33.8% during third-line treatment. Topical corticosteroids were the most commonly prescribed treatment, mostly leading to stable disease (46.6%). Combined full and partial remission occurred in a large proportion of patients receiving UVA1 (45%), PUVA (63.6%) and intralesional triamcinolone acetonide (100%).

CONCLUSIONS

Generalized granuloma annulare is a mostly asymptomatic and benign disease with a strong tendency for treatment resistance. We suggest to screen all patients for dyslipidemia, thyroid disease and malignant disease. While randomized trials are needed, we suggest topical corticosteroids as the first-line treatment, intralesional triamcinolone acetonide for persistent solitary lesions and, if further treatment is needed, UVA1 or PUVA.

Cutaneous Granulomatosis: a Comprehensive Review

Cutaneous granulomatosis is a heterogeneous group of diseases, characterized by a skin inflammatory reaction triggered by a wide variety of stimuli, including infections, foreign bodies, malignancy, metabolites, and chemicals. From a pathogenic point of view, they are divided into non-infectious and infectious granulomas. Pathophysiological mechanisms are still poorly understood. Non-infectious granulomatous skin diseases include granuloma annulare, necrobiosis lipoidica, rheumatic nodules, foreign body granulomas, cutaneous sarcoidosis, and interstitial granulomatous dermatitis. Necrobiosis lipoidica is more frequent in diabetic patients. Infectious granulomas of the skin are caused by mycobacteria, in particular Mycobacterium tuberculosis or atypical mycobacteria; parasites, such as Leishmania; or fungi. Pathogenic mechanisms of M. tuberculosis-related granuloma are discussed. From a clinical point of view, it is useful to divide cutaneous granulomatosis into localized and more disseminated forms, although this distinction can be sometimes artificial. Three types of localized granulomatous lesions can be distinguished: palisaded granulomas (granuloma annulare, necrobiosis lipoidica, and rheumatoid nodules), foreign body granulomas, and infectious granulomas, which are generally associated with localized infections. Disseminated cutaneous granulomas can be divided into infectious, in particular tuberculosis, and non-infectious forms, among which sarcoidosis and interstitial granulomatous dermatitis. From a histological point of view, the common denominator is the presence of a granulomatous inflammatory infiltrate in the dermis and/or hypodermis; this infiltrate is mainly composed of macrophages grouped into nodules having a nodular, palisaded or interstitial architecture. Finally, we propose which diagnostic procedure should be performed when facing a patient with a suspected cutaneous granulomatosis.

Granuloma Annulare: A Focused Review of Therapeutic Options

Granuloma annulare (GA) is a benign inflammatory disease associated with many conditions such as malignancy, trauma, thyroid disease, diabetes mellitus, and HIV infection. Common clinical subtypes include localized GA, generalized GA, subcutaneous GA, perforating GA, and patch GA. There exists an abundance of literature on GA, yet we know relatively little about its exact etiology and even less about its treatment. The paucity of conclusive data on effective treatment options is largely because the majority of published studies are limited to small case reports, case series, and retrospective studies. As such, there does not yet exist a gold standard of care to guide clinical management. Depending on the clinical subtype, the clinical prognosis for GA can vary. The localized variant generally self-resolves within 2 years without treatment, whereas the generalized form is more chronic and less responsive to treatment. This focused up-to-date review serves to summarize the latest therapeutic options available for GA.

Histopathologic review of granulomatous inflammation

Granulomatous inflammation is a histologic pattern of tissue reaction which appears following cell injury. Granulomatous inflammation is caused by a variety of conditions including infection, autoimmune, toxic, allergic, drug, and neoplastic conditions. The tissue reaction pattern narrows the pathologic and clinical differential diagnosis and subsequent clinical management. Common reaction patterns include necrotizing granulomas, non necrotizing granulomas, suppurative granulomas, diffuse granulomatous inflammation, and foreign body giant cell reaction. Prototypical examples of necrotizing granulomas are seen with mycobacterial infections and non-necrotizing granulomas with sarcoidosis. However, broad differential diagnoses exist within each category. Using a pattern based algorithmic approach, identification of the etiology becomes apparent when taken with clinical context. The pulmonary system is one of the most commonly affected sites to encounter granulomatous inflammation. Infectious causes of granuloma are most prevalent with mycobacteria and dimorphic fungi leading the differential diagnoses. Unlike the lung, skin can be affected by several routes, including direct inoculation, endogenous sources, and hematogenous spread. This broad basis of involvement introduces a variety of infectious agents, which can present as necrotizing or non-necrotizing granulomatous inflammation. Non-infectious etiologies require a thorough clinicopathologic review to narrow the scope of the pathogenesis which include: foreign body reaction, autoimmune, neoplastic, and drug related etiologies. Granulomatous inflammation of the kidney, often referred to as granulomatous interstitial nephritis (GIN) is unlike organ systems such as the skin or lungs. The differential diagnosis of GIN is more frequently due to drugs and sarcoidosis as compared to infections (fungal and mycobacterial). Herein we discuss the pathogenesis and histologic patterns seen in a variety of organ systems and clinical conditions.

Etiology, diagnosis, and therapeutic management of granuloma annulare: an update

Granuloma annulare (GA) is a common cutaneous disorder classically presenting as annular groups of skin-colored to erythematous papules without epidermal change localized to the dorsal hands and/or feet. In addition to the localized form, there are variants including generalized (including generalized annular GA, disseminated papular GA, and atypical generalized GA), subcutaneous, and perforating GA, providing for a wide spectrum of clinical lesions. The etiology of GA remains unknown and several systemic associations have been proposed but not proven, including diabetes mellitus, malignancy, thyroid disease, and dyslipidemia. The diagnosis of GA relies on clinicopathological correlation, with a skin biopsy confirming the histological features of the disease, including palisading granulomas, collagen degeneration, mucin, and a lymphohistiocytic infiltrate. Localized GA is often asymptomatic and self-limited within 2 years; however, the patient may desire treatment for cosmetic reasons, with topical and intralesional corticosteroids as the mainstays of therapy. When GA is generalized, disseminated, or atypical, a more thorough medical workup for underlying diseases may be considered depending on the physical examination, a thorough review of systems, comorbidities, and clinical suspicion. Treatment is often challenging for generalized GA, especially because of its recalcitrant nature and a lack of evidence-based therapy. Over 30 different treatments have been described for GA with variable results; however, the majority of these have been single case reports, small case series, or retrospective studies. Reported treatments for GA include topical, intralesional, intramuscular, and oral medications (steroidal vs. non-steroidal); biologic agents; surgical interventions; phototherapy; and laser treatments. When selecting a systemic therapy for a patient with GA, multiple variables must be considered, such as baseline blood evaluations, comorbidities, drug interactions, compliance, adverse effect profiles, prior treatments, and reproductive status. This evidence-based review will focus on the advances made in the twenty-first century regarding the etiology, diagnosis, and therapeutic management of GA.