Pathology of Necrobiosis
lipoidica , originally known as necrobiosis lipoidica diabeticorum, is a disorder of collagen degeneration with a granulomatous response and
thickening of blood vessels.
Diabetes mellitus is present in more than half the patients with necrobiosis lipoidica.
Age and sex:
Average age of onset is 30 years (may occur at any age) and females are commonly affected.
Most cases are located on the leg specially above the tibiae, but may also occur on the face, scalp, forearm and trunk.
Lesions may be single but multiple lesions are more common.
Necrobiosis lipoidica may present as red papules which may enlarge to form patches or plaques with an atrophic yellowish-brown and slightly depressed center.
The lesions may resolve spontaneously or become persistent chronic
lesions which may ulcerate.
Intradermal nerves are reduced in number.
Old and atrophic lesions show dermal fibrosis and thickened septa of the subcutaneous fat.
Lipid in the upper part of the dermis can be demonstrated by Sudan black and oil red O stain.
Stains for mucin (colloidal iron or alcian blue) are usually negative.
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