eMedicine Specialties > Dermatology > Reactive & Inflammatory Dermatoses

Granuloma Annulare

Author: Ruby Ghadially, MB, FRCP(C)Derm, MB, BCh, Professor of Dermatology, Department of Dermatology, University of California at San Francisco
Coauthor(s): Amit Garg, MD, Director of Clinical Elective in Dermatology, Assistant Professor, Department of Internal Medicine, Division of Dermatology, University of Massachusetts Medical School
Contributor Information and Disclosures

Updated: Mar 14, 2007

Introduction

Background

T. Colcott Fox first described granuloma annulare (GA) in 1895; however, it was not until 1902 that Radcliffe-Crocker labeled it as GA.

GA is a benign inflammatory dermatosis characterized clinically by dermal papules and annular plaques. Its precise cause is unknown. Histological examination reveals foci of degenerative collagen associated with palisaded granulomatous inflammation.

The following clinical variants are recognized:

• Localized GA
• Generalized GA
• Subcutaneous GA
• Perforating GA
• Arcuate dermal erythema

Some authorities consider actinic granuloma (AG) to be a subset of GA, but others view it as a separate but related entity.

Pathophysiology

Proposed pathogenic mechanisms include cell-mediated immunity (type IV), immune complex vasculitis, and an abnormality of tissue monocytes. None has convincing supporting evidence.

Frequency

International

GA is an uncommon dermatosis whose frequency in the general population is unknown. Localized GA is the most common among the various subtypes. Of all patients with GA, 9-15% have the generalized variant. Perforating GA has been reported to have a prevalence of 5% among GA subtypes, although reports suggest that this variant may be more common in the Hawaiian Islands. The other subtypes are uncommon variants.

Mortality/Morbidity

Most cases resolve without adverse medical sequelae.

Sex

Women are affected twice as often as men.

Age

• Localized GA is most commonly found in children and in adults younger than 30 years.
• Generalized GA demonstrates a bimodal age distribution, occurring in patients younger than 10 years and in patients aged 30-60 years.
• Although subcutaneous GA can occur in adults, it is predominantly a disease of otherwise healthy children, who are typically aged 2-10 years. Similarly, perforating GA most often affects children.

Clinical

History

• Both localized and generalized GA lesions usually manifest as asymptomatic cutaneous lesions. Lesions may improve in winter and worsen in summer.
• Subcutaneous GA most often manifests as a large, asymptomatic soft tissue mass. Although nodules are usually stable for months, they may rapidly enlarge over the course of weeks.

Physical

• Patients with localized GA commonly present with groups of 1- to 2-mm papules that range in color from flesh-toned to erythematous, often in an annular arrangement over distal extremities.
  • Grouped lesions may expand into arciform or annular plaques measuring 1-5 cm in diameter.
  • Centers of lesions may be slightly hyperpigmented and depressed relative to their borders, which may be solid or composed of numerous dermal papules.
  • Lesions most commonly manifest on the dorsal surfaces of the feet, hands, and fingers, and on the extensor aspects of the arms and legs.
  • Rarely, lesions appear on the face, scalp, or penis.
• Patients with generalized GA characteristically present with a few to thousands of 1- to 2-mm papules or nodules that range in color from flesh-toned to erythematous and involve multiple body regions.
  • Lesions may coalesce into annular plaques, which measure 3-6 cm in diameter and which may enlarge centrifugally over weeks to months.
  • Although any part of the cutaneous surface may be involved, lesions tend to be symmetrically disposed over acral areas and the trunk.
  • Rarely, the head, palms, soles, and mucous membranes are involved.
• Patients with subcutaneous GA present with a firm, nontender, flesh-colored or pinkish nodule without overlying epidermal alteration.
  • Lesions are typically solitary but may occur in clusters.
  • The most commonly reported site of involvement is the lower extremities (65% of cases), often on the pretibial surface.
  • Other typical sites include the fingers and palms and the dorsa of the feet.
  • The buttocks, forehead, and scalp are less commonly affected.
  • Deep dermal or subcutaneous nodules on the extremities are attached to fascia and are often therefore mobile, whereas lesions on the scalp are attached to underlying periosteum and are therefore fixed or only slightly mobile.
• Patients with perforating GA present with 1 to hundreds of grouped 1- to 4-mm papules that range in color from flesh-toned to erythematous.
  • Papules often coalesce to form annular plaques.
  • In some patients, the erythematous papules may evolve into yellowish pustular lesions that subsequently exude a thick and creamy or clear and viscous fluid, forming umbilicating, crusting, or scaling papular lesions that heal, leaving atrophic hypopigmented or hyperpigmented scars.
  • Larger and more ulcerated plaques are common in middle-aged and elderly patients.
  • Lesions affect all areas of the body but have a predilection for the extensor surfaces of extremities and the dorsa of hands and fingers.
• Arcuate dermal erythema is an uncommon form of GA that manifests as infiltrated erythematous patches that may form large, hyperpigmented rings with central clearing. Papules are a less prominent feature in this variant. Patches typically appear on the trunk and may spread centrifugally over weeks to months.
• Patients with AG present with 1-10 plaques, which tend to be annular or serpiginous areas with raised erythematous borders.
  • Lesions may be hypopigmented centrally; the epidermis is otherwise spared.
  • Plaques are typically distributed over sun-exposed areas, such as the arms, neck, face, and dorsa of the hands.
  • Other than by their location on heat- or sun-damaged skin, AG lesions are difficult to distinguish clinically from eruptions of GA.

Causes

• GA has traditionally been hypothesized to be associated with tuberculosis, insect bites, trauma, sun exposure, thyroiditis, and viral infections, including HIV, Epstein-Barr virus, and herpes zoster virus. However, these suggested etiologic factors remain unproven.
• Familial cases of GA observed in identical twins and siblings in several generations, along with an association of GA with HLA phenotypes, suggest the possibility of a hereditary component in some cases. The HLA-B8 level has been reported to be increased in localized GA; HLA-A29 and HLA-BW35 levels are reported to be increased in generalized GA.
• Relationship to systemic diseases
  • GA has been associated with diabetes mellitus and thyroid disease based on an increased number of GA patients with these diseases in small case series. The evidence for a relationship with GA is weak.
  • Small case series have reported GA to occur in association with malignancy, AIDS, and herpes zoster lesions. Although no definite patterns relating GA and systemic disease have been thoroughly established, it has been suggested that an atypical histologic (vasculopathy or extravascular neutrophilia) or clinical presentation (unusual appearance or location) may indicate an associated disease. In the case of malignancy, a recent study by Li et al (2003) reviewed classic cases in the literature and could find no definite relationship between GA and malignant neoplasms.

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