Skin-nontumor / Clinical dermatology
Other dermatoses
Subcutaneous fat necrosis of newborn

Author: Mowafak Hamodat, M.D., MB.CH.B, MSc., FRCPC (see Authors page)

Revised: 21 July 2016, last major update August 2011

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Subcutaneous fat necrosis of newborn

Definition / General
  • Uncommon disorder of infants in good health with lesions on trunk, extremities, buttocks, cheeks
  • Hypercalcemia has been reported in some cases; thrombocytopenia, hypoglycemia and hypertriglyceridemia may also develop
  • Lactic acidosis and hyperferritinemia were each present in one case
  • Numerous possible causes, including obstetrical trauma, hypothermia, asphyxia, anemia, forceps delivery, macrosomia, exposure to active or passive smoking during pregnancy, prostaglandin E administration, maternal exposure to cocaine or calcium channel blockers
Clinical Features
  • Indurated areas and distinct nodules with a predilection for the cheeks, shoulders, buttocks, thighs and calves
Case Reports
Micro Description
  • Basophilic fat necrosis, clusters of needle like clefts in lipocytes and histiocytes
  • Clefts may contain refractile crystals
  • Variable granulomatous inflammation and small calcium deposits
  • Normal epidermis and dermis with an underlying lobular panniculitis
  • Focal fat necrosis is present and this may lead to fat cyst formation
  • Lymphocytes, histiocytes, foreign body giant cells and sometimes a few eosinophils wedged between the fat cells
  • Many fat cells retain their outline but contain fine, eosinophilic cytoplasmic strands and granules, between which are narrow clefts radiating from a point near the periphery of the cell; clefts contain doubly refractile crystals, representing triglycerides, on frozen section
  • Similar fine, needle-like crystals can be seen in giant cells
  • Older lesions have fibrosis between fat cells
Electron Microscopy Description
  • Intact and necrotic fat cells containing needle-shaped crystals arranged radially or in parallel
  • Dense granular material is also present in necrotic fat cells, which are surrounded by macrophages
Additional References