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Skin-nontumor

Other dermatoses

Granuloma annulare


Reviewer: Mowafak Hamodat MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns (Canada) (see Reviewers page)
Revised: 31 July 2011, last major update July 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

Definition
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● Benign self-limited dermatosis characterized by raised annular lesions

Clinical features
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● Self-limited, asymptomatic disorder of dorsum of hands and legs, occasionally generalized
● Associated with morphea, chronic hepatitis C infection, autoimmune thyroiditis, secondary hyperparathyroidism, Plummerís disease, myelodysplastic syndrome, metastatic carcinoma
● Rarely associated with diabetes and disseminated
● Some cases are persistent
● 50% resolve within 2 years
● May regress spontaneously after biopsy
● May recurred seasonally in sun exposed areas
Pseudorheumatoid nodules: also called giant granuloma annulare; large, isolated, and deep necrobiotic collagen granulomas in extremities or occupate of children, may be limited to penis; not associated with rheumatoid or rheumatic disease; may affect siblings

Case reports
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● 78 year old woman with lesions on palms (Dermatol Online J 2011;17:7)

Treatment
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● Localized lesions are self-limited - treatment not needed
● Various options for disseminated disease (eMedicine)

Clinical description
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● One or several papules, skin colored, red or violaceous, which form 1-5 cm annular or arcuate lesions

Clinical images
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Granuloma annulare of leg

   
Various images

Micro description
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● Mid dermal necrobiotic collagen center surrounded by palisading histiocytes, as well as fibroblasts and lymphocytes
● Occasional foreign body giant cells, vasculitis and mucin
● May need multiple sections to find necrobiotic collagen

Micro images
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H&E (left) and Alcian Blue at pH 2.5 (right)


Palisaded granulomatous infiltrate of lymphocytes and histiocytes around a central zone of degenerated collagen; many histiocytes are multinucleated and exhibit elastophagocytosis


Granuloma annulare of palms: interstitial lymphohistiocytic infiltrate and focal increased mucin deposition in mid dermis

   
Interstitial pattern

       
Generalized perforating lesions

Positive stains
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● Histiocytes: vimentin, lysozme, CD68

Negative stains
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● Histiocytes: Ham56

Electron microscopy
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● Degenerated elastic fibers

Differential diagnosis
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Rheumatoid arthritis and rheumatic fever nodules: different clinical presentation
Annular elastolytic giant cell granuloma: histiocytes and foreign body giant cells engulfing elastotic fibers; may be a related entity
Necrobiosis lipodica: ill defined areas of disintegrating dermal collagen, surrounded by palisading lymphocytes and histiocytes, with thick walled vessels, usually in reticular dermis

Additional references
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AOCD

End of Skin-nontumor > Other dermatoses > Granuloma annulare


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