1.4.2 Granuloma annulare

Granuloma annulare is a granulomatous dermal and/or subcutaneous disorder characterised by infiltrating mononuclear cells that presents with skin-coloured or reddish, annular or papular lesions related to different aetiologic background.

It is more common in children, young adults and people with diabetes mellitus.

The cause of granuloma annulare is unclear. It can be associated with autoimmune diseases or diabetes mellitus. Granuloma annulare can be caused by a large number of certain drugs. Disseminated forms have been described in association with HIV infection or cancer (solid cancers or haematological malignancies). Other comorbidities are significant associations with hyperlipidemia, rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE).

Granuloma annulare consists of localized or disseminated firm, small, skin-coloured or reddish papules arranged in rings or arcs, or hard, mobile, dermal and subcutaneous nodules.

Generally, there are no associated symptoms and the size of the lesions is only a few centimeters. It may be localized or generalized (disseminated).

Granuloma annulare typically appears on the extensor surfaces of the extremities (especially fingers and dorsum of hands). In its disseminated form, the trunk is also often involved.

The lesions can present as localized, disseminated, subcutaneous, perforating types or patch-type.

In isolated granuloma annulare no laboratory testing is needed. In disseminated granuloma annulare, HIV serology, complete blood count, hyperglycemia and lipid profile may be tested. Autoimmune diseases and cancers can be looked for, depending on the clinical context. Unusual courses and clinical aspects of the disease need histological confirmation.

Granuloma annulare is characterized by bundles, degenerative collagen bundles (necrobiosis) with a peripheral cuff of lymphocytes and histiocytes and a palisadic organisation of the granuloma (palisading pattern). The interstitial pattern is characterized by histiocytes between collagen bundles with mucin deposition in the superficial and mid dermis.

There are no complications, except for granuloma annulare associated with an underlying disease. In rare subsets, a perforating course of the lesions can be seen.

Therapeutic abstention except detection of underlying disease or psychoreactive reactions, topical corticosteroids, topical calcineurin inhibitor or cryotherapy are possible in limited forms.

In disseminated forms, phototherapy, dapsone, retinoids, hydroxychloroquine and TNF alpha blockers can be considered. Recently, TNF alpha antagonist (adalimumab) have been reported to be very successful. In the disseminated and polyarthritis-associated types, treatment with biologics. The treatment of these disseminated forms is generally difficult. Strong regulation of diabetic metabolism is mandatory. Rheumatic diseases must be treated with appropriate medications.

Preventive measures are not possible.