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Skin-nontumor

Other dermatoses

Necrobiosis lipoidica


Reviewer: Mowafak Hamodat MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns (Canada) (see Reviewers page)
Revised: 1 August 2011, last major update August 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

Definition
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● Atrophic, yellow depressed plaques, usually on legs of diabetic patients

Clinical features
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● Also associated with hypo- and hyperthyroidism, inflammatory bowel disease and vasculitis

Clinical description
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● Atrophic, yellow depressed plaques, telangiectasia, and active inflammatory edge
● Chronic lesions may show ulceration and crusting
● Solitary or multiple, often symmetrical in lower extremities in pretibial area
● Involvement of penis with a lesion resembling chronic balanitis has been described
● Rarely, squamous cell carcinoma may arise in chronic lesions

Clnical images
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Various images

Micro description
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● Epidermal changes may be inconspicuous or absent; variable acanthosis, atrophy or hyperkeratosis
● Palisading, necrobiotic granuloma consist of a large confluent area of necrobiosis centered in the superficial dermis and subcutaneous fat
● Usually epithelioid histiocytes, giant cells and sometimes a well formed granuloma
● Eosinophilic, swollen or degenerate collagen appears hyalinised with surrounding infiltrate of lymphocytes and histiocytes
● Linear infiltrate of histiocytes between collagen bundles; occasionally lipomemebranous fat necrosis
● Blood vessel wall thickening with intimal proliferation and narrowing of the lumen; also mild to moderate perivascular lymphocytic infiltrate
● Plasma cells are almost always present
● Cholesterol clefts are rare
● Loss of elastic tissue

Micro images
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Necrobiosis lipoidica

Negative stains
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● Lysozyme, mucin

Differential diagnosis
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Granuloma annulare: mucin+, lysozyme+, and no association with diabetes
Necrobiotic xanthogranuloma: head and neck of patients with paraproteinemia, not associated with diabetes

Additional references
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eMedicine

End of Skin-nontumor > Other dermatoses > Necrobiosis lipoidica


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