Subcutaneous Fat Necrosis of the Newborn

What is Subcutaneous Fat necrosis of the newborn ?

• It is a lobular panniculitis.
• It is associated with complications during labor (labour)
• It presents as asymptomatic indurated subcutaneous dark-red nodules which are typically located in bone proeminant areas (upper back, proximal limbs, cheeks…)

When does it occur ?

• It occurs between 1 and 5 weeks following delivery.

Why does it happen ?

It is largely unknown but here is a hypothesis:

• Fat in the newborn contains a higher proportion of saturated fat; more exactly palmitate (palimitic acid). Saturated fat has a lower melting point (solid to liquid transition), which means that it crystallizes more easily.
• Because of fetal suffering (which consists of meconium aspiration, preeclampsia, prolonged labor, caesarean section…)…there is injury to the subcutaneous fat tissue which then crystallizes.

How does it evolve ?

• It resolves itself spontaneously within one to 4 months.
• There is no scar.
• Complications are of hypercalcemia which can lead to cardiac, neurological, and/or nephrologic impairement.

What is the differential diagnosis ?

• Diagnosis is usually straightforward but Sclerema Neonatorium must be differentiated. It is a diffuse subcutaneous sclerosis which heals with fibrosis.
• It is considered by some as an extensive form of subcutaneous fat necrosis.

One word on the classification of panniculitis

• Panniculitis is classified into septal, lobular or mixed forms.
• Although not exhaustive here, causes of lobular panniculitis include, lupus panniculitis, infectious panniculitis, erythema induratum of Bazin. Septal causes include erythema nodosum.

Comment: In the French literature, it is entrenched in the mind of some dermatologists that “panniculite” is used for lobular panniculitis.

Source of Information:

Laffitte E. 2012 (09) – 21st Annual Congress of the EADV (European Academy of Dermatology and Venerology) – Prague (Praha), Czech Republic (česká republika)

Dubertret L. Thérapeutique Dermatologique, 2011 Online Edition