Skin nontumor

Dermal granulomatous and necrobiotic reaction patterns

Necrobiosis lipoidica



Last author update: 1 August 2011
Last staff update: 9 February 2024

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PubMed Search: Necrobiosis lipoidica

Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hamodat M. Necrobiosis lipoidica. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumornecrobiosislipoidica.html. Accessed April 14th, 2024.
Definition / general
  • Atrophic, yellow depressed plaques, usually on legs of diabetic patients
Clinical features
  • Also associated with hypo and hyperthyroidism, inflammatory bowel disease and vasculitis
  • 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
Clinical images

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Necrobiosis lipoidica diabeticorum

Microscopic (histologic) description
  • 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
Microscopic (histologic) images

Contributed by Gaurav Jain, M.B.B.S., M.D.
Degenerated collagen alternating with inflammation

Degenerated collagen alternating with inflammation

Layers of degenerated collagen

Layers of degenerated collagen

Degenerated collagen

Degenerated collagen

Negative stains
Differential diagnosis
  • Granuloma annulare: mucin+, lysozyme+
  • Necrobiotic xanthogranuloma: head and neck of patients with paraproteinemia, not associated with diabetes
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