This is a benign inflammatory condition of unknown aetiology with dermal papules and annular plaques. Histology reveals foci of degenerative collagen with palisaded granulomatous inflammation. It may be associated with diabetes but association with systemic disease is rare.¹

Five variants of the condition are recognised:

1. Localised
2. Generalised
3. Subcutaneous
4. Perforating
5. Arcuate dermal erythema (some regard it as a separate entity)

Epidemiology

It is an uncommon condition and figures on incidence are not available. Localised is the most common type. Generalised represents about 10-15% of cases. Perforating is about 5%.

Women are affected twice as often as men. The localised type is usually found in those under 30 years old. The generalised type has peaks at age under 10 and age range 30-60 years. The subcutaneous type affects children aged 2-10 and the perforating type is also a disease of children.

History

Both localised and generalised varieties are usually asymptomatic lesions that may improve in winter and deteriorate in summer. The subcutaneous variety is often a large subcutaneous mass. They may be stable for months and then enlarge over weeks.

Examination

Localised lesions are usually groups of papules, about 1-2 mm in diameter with possible erythema. They tend to form an arc or a ring 1-5 cm in diameter. The centre of lesions may be slightly depressed and hyperpigmented. They are usually on the dorsal surfaces of hands, feet and fingers and the extensor surface of arms and legs.

The generalised variety has a similar appearance to the lesions but they are more numerous and more diffuse. They may coalesce into annular plaques 3-6 cm in diameter and these can expand over weeks or months. They tend to be on limbs or trunk.
Subcutaneous lesions are firm, skin-coloured or pink, not tender and the overlying skin looks normal. They are usually solitary lesions but can occur in clusters. The lower limb, especially the pretibial surface is the most common area. Lesions are mobile, except on the scalp.

Perforating lesions are papules 1-4 mm in diameter with possibly some degree of erythema. They may be solitary or number in hundreds but often coalesce to form annular plaques. They tend to be larger and more ulcerated in middle-aged or elderly people and the lesions may leave hyperpigmented or hypopigmented scars. They tend to be on the extensor surface or lower arms or legs or the dorsal surface of hands.

Arcuate dermal erythema is the rarest form. It produces infiltrated erythematous patches that may form large, hyperpigmented rings with central clearing. Papules are less pronounced. Lesions typically appear on the trunk and may spread centrifugally over weeks to months.

Images

Investigations

Diagnosis is essentially clinical and laboratory tests are not helpful unless another diagnosis is suspected. If in doubt, biopsy may be helpful.

Differential diagnosis

Lichen planus, sarcoidosis, rheumatoid nodules

Management

The local type tends to be indolent but the generalised type may produce cosmetic embarrassment. A number of treatments are effective.

• Intralesional steroid injection is almost always effective for local disease but less effective and less practical in generalised disease, and more steroid is needed.
• Potent steroid creams may be enhanced by using under occlusion.
• Cryotherapy works but may cause hypopigmentation or hyperpigmentation. Some regard it as the treatment of choice.²
• Generalised disease is not so amenable to the steroid treatment and is also less likely to resolve spontaneously. Systemic treatments have been disappointing. There are many options, none of which is satisfactory. They include psoralen + UVA (PUVA) treatment³, oral steroids, dapsone, chlorambucil and ciclosporin. Trials have usually been small. The tumour necrosis factor inhibitor infliximab may be useful in recalcitrant cases.⁴
• With subcutaneous lesions in children, the best management is reassurance.⁵
• Treatment of perforating lesions is disappointing.⁶

Prognosis

In untreated localised disease the lesions may last weeks or decades. Half will disappear inside two years but, in 40%, they will recur.
The prognosis for generalised disease is much worse with a chronic course, poor response to treatment, low chance of spontaneous remission and, if it does occur, high risk of recurrence.
Subcutaneous lesions often resolve spontaneously but may recur elsewhere.

Document references

1. Barron DF, Cootauco MH, Cohen BA; Granuloma annulare. A clinical review.
2. Zouboulis CC; Cryosurgery in dermatology. Eur J Dermatol. 1998 Oct-Nov;8(7):466-74. [abstract]
3. Kerker BJ, Huang CP, Morison WL; Photochemotherapy of generalized granuloma annulare; Arch Dermatol 1990 Mar;126(3):359-61.[abstract]
4. Hertl MS, Haendle I, Schuler G, et al; Rapid improvement of recalcitrant disseminated granuloma annulare upon treatment with the tumour necrosis factor-alpha inhibitor, infliximab; Br J Dermatol 2005 Mar;152(3):552-5.[abstract]
5. Felner EI, Steinberg JB, Weinberg AG; Subcutaneous granuloma annulare: a review of 47 cases. Pediatrics. 1997 Dec;100(6):965-7. [abstract]
6. Penas PF, Jones-Caballero M, Fraga J, et al; Perforating granuloma annulare. Int J Dermatol. 1997 May;36(5):340-8. [abstract]

Internet and further reading

• Ghadially R, Garg A, Granuloma Annulare, eMedicine Aug 2009

Acknowledgements