Granuloma annulare (GA) is a benign
inflammatory, self-limiting granulomatous dermatoses that is seen in
both adults and children
Females are more commonly affected than
The lesions may involve skin and/or subcutaneous tissue.
The etiology of GA is unknown.
The lesions could be related to insect
bites, sun exposure, viral infections, diabetes, thyroiditis,
immunoglobulin-mediated vasculitis, and certain medications such
as antibiotics, antiinflammatory agents and oral contraceptives.
have also been reported in patients with AIDS, sarcoidosis, hepatitis C
infection, Hodgkin's and non Hodgkin's lymphoma, metastatic
adenocarcinoma and granulomatous mycosis fungoides.
(1) Localized - Children & young adults. Papules & annular or arciform
Site: Hands, feet, arms & legs.
(2) Generalized - Middle aged and elderly patients. Multiple macules,
papules or nodules.
Site: Trunk & limbs.
(3) Perforating - Middle aged & elderly females. Papules & annular
plaques. Scaling & crusting with central umbilication may be present.
Site: Dorsa of the hands and feet.
(4) Subcutaneous or deep form - Children & young adults. Solitary or
multiple nodules (a few millimeters to several centimeters in size).
Lower extremities, dorsa of the hands & feet, buttock and scalp.
Histological patterns in
1. Necrobiotic granuloma
2. Interstitial or 'incomplete' form - Most common
3. Granuloma of sarcoidal or tuberculoid type: Rare
|Features of Necrobiotic
Granulomas in the Dermis:
- Located in the
superficial and mid dermis.
- Areas of necrobiosis surrounded by peripheral rim of histiocytes and
- Multinucleated giant cells (+/-)
- Intervening areas of dermis between the necrobiotic granulomas is
- Central necrobiotic area contains abundant connective tissue mucins
which is lightly basophilic in apperance. Mucin stains (Colloidal iron
and alcian blue) are useful.
- Small amounts of fibrin may be present as fibrillary eosinophilic
- Perivascular infiltrate of lymphocytes in superficial & mid dermis.
- Neutrophils and nuclear dusts are present in some cases.
- Vasculitis may be present near foci of necrobiosis.
Multilayered necrobiosis (stacks of plates) with open ends.
Numerous plasma cells.
Thickened collagen bundles within palisaded granuloma.
Diffuse process present throughout the reticular dermis.
Features of interstitial or
'incomplete' form of Granuloma Annulare:
- Should be assessed under low power.
- "Busy dermis" - increased number of inflammatory cells in the dermis
separated by connective tissue mucin.
- Infiltrate composed of lymphocytes and histiocytes.
- Inflammatory cells are noted around blood vessels and between
- No well-defined areas of necrobiosis
(1) Interstitial granulomatous drug reaction: Eosinophils (+) , lichenoid changes
at dermoepidermal junction , true necrobiosis is rarely noted .
(2) Interstitial granulomatous dermatitis : Neutrophils,
neutrophil fragments, histiocytes, lymphocytes & eosinophils are present
, palisades of histiocytes around
basophilic collagen fibres.
Changes may involve the full thickness of
Features of Subcutaneous Granuloma Annulare-(Pseudorheumatoid
- Located in the deep dermis, subcutis and rarely deep soft tissue.
- Area of necrobiosis is larger than the superficial type.
- Granulation tissue and lymphoid aggregates may be present near
- Eosinophils are more common in this variant.
Rheumatoid nodule and
subcutaneous granuloma annulare. A comparative histologic study.Am
J Dermatopathol. 1988 ;10(1):1-8.
Necrobiotic foci contain abundant fibrin. Degenerated bundles of
collagen (+/-). Palisade of elongated histiocytes.
Features of disseminated form
of granuloma annulare:
- Poorly formed granulomatous foci in the papillary dermis.
- Necrobiosis is not prominent.
Lichen Nitidus :
Claw-like acanthotic elongation of rete-ridges at the periphery of the
lesion is absent in GA.
Non-necrobiotic sarcoidal or
tuberculoid type of GA:
Dermal mucin and eosinophils help in distinguishing this lesion from
connected to the underlying necrobiotic granuloma.