Haematoma complicating subcutaneous fat necrosis of the newborn: a rare complication following therapeutic hypothermia

Background

Neonatal hypoxic-ischaemic encephalopathy (HIE) is a major global health problem with more than one million new cases annually. Fifteen to twenty per cent of the affected neonates die in the neonatal period, and 40% suffer neurodevelopmental complications.1 Therapeutic hypothermia (TH) is a standard of care for term and near-term infants ≥35 weeks gestational age with moderate-to-severe HIE. Evidence from multiple randomised trials has established that TH improves survival without disability to infancy and mid-childhood.2 TH is generally safe. However, transient adverse effects commonly occur with TH in the background of asphyxia, including bradycardia, hypotension and prolonged coagulation profiles.3 Subcutaneous fat necrosis (SCFN) is a known complication of TH occurring in about 3% of patients undergoing TH for HIE.4 SCFN is a self-limited condition with occasional association with hypercalcaemia, which may be life threatening, requiring careful monitoring and treatment.5 We report an unusual case of SCFN that presented as a large, rapidly progressive subcutaneous haematoma requiring surgical intervention in a term baby following TH.

Case presentation

A male newborn weighing 3.99 kg (>90th% of birth weight and gestation) was delivered by caesarian section for decreased fetal movements after induced labour. The mother was G6P2, with a history of three previous spontaneous abortions. This pregnancy was complicated with gestational diabetes and hypothyroidism.

The baby was born through meconium-stained amniotic fluid. He was non-vigorous at birth with apnoea and bradycardia, requiring endotracheal intubation and chest compression for 3 min. Apgar scores were 1, 2, 4 and 4 at 1, 5, 10 and 15 min, respectively. Cord arterial pH was 6.69 and base deficit of −21.7. The baby had clinical signs of severe encephalopathy, and he was treated with TH using a total body cooling blanket. The target temperature of 33–34°C was reached at about 4 hours of age and continued for 72 hours. Seizures were noted at 2 hours of age, and his amplitude integrated electroencephalography tracing (aEEG) showed a burst suppression pattern. Brain MRI and magnetic resonance spectroscopy on day 5 of life showed evidence of injury in deep grey matter and watershed area with bilateral intraventricular haemorrhage associated with post haemorrhagic hydrocephalus.

The baby’s condition was complicated with meconium aspiration syndrome, which was treated with surfactant administration and high-frequency mechanical ventilation. The seizures were treated with phenobarbitone, levetiracetam and fosphenytoin. He had hypotension that required treatment with multiple fluid boluses, multiple inotropes and steroids. He developed pulmonary hypertension (PPHN) that was treated with inhaled nitric oxide (iNO), milrinone and prostaglandin E1 infusion. He had a low platelet count with abnormal coagulation profile that required multiple transfusions of platelets and fresh frozen plasma.

After 48 hours on total body cooling, the baby developed tender, indurated subcutaneous nodules consistent with SCFN. It initially started over the back but gradually spread to cover both shoulders, upper arms, chest area and both thighs (figure 1).

Over the following days, the baby was gradually weaned from inotropic support but stayed on mechanical ventilation, iNO and milrinone for PPHN. He continued to receive daily platelet transfusion for thrombocytopenia. Serum calcium level was normal, and he was supplemented with oral vitamin D by day 14 of life as he reached full feeding of expressed breast milk.

On day 19 of life, multiple small nodules on the back softened and merged to form one large fluctuant swelling over the thoracolumbar area. The swelling was initially small, soft and tender but rapidly progressed over few hours to a large, tense mass measuring 10×7 × 7 cm with sloughing of a gangrenous overlying skin (figure 2). The baby’s clinical condition did not change on mechanical ventilation. He was haemodynamically and neurologically stable and received morphine for pain. The baby’s laboratory tests showed thrombocytopenia and abnormal coagulation profile, which improved after transfusion of platelet, fresh frozen plasma and cryoprecipitate.

Investigations

The ultrasonographic examination of the baby’s back revealed a well-defined oval heterogeneous mass with both solid and cystic components within the subcutaneous tissues. Its measurements were approximately 10.8×6.9×4.4 cm in size. With no internal vascularity on colour Doppler assessment, the lesion was considered to be a haematoma.

A sample from the skin and adipose tissue of the haematoma was sent for pathological analysis. Microscopic examination demonstrated extensive SCFN exhibiting classical features of SCFN of the newborn. The overlying skin appeared extensively necrotic. The pathological examination of the specimen did not identify an apparent cause for the described haematoma. The scattered vessels (arteries and veins) identified in the subcutis appeared normal.

Treatment

On day 23 of life, the baby underwent surgical evacuation and debridement of the haematoma under general anaesthesia. The overlying necrotic skin was excised at the same time, leaving an open wound measuring 13×7 cm on the baby’s back (figure 3).

The large back wound that resulted was dressed with negative-pressure wound therapy (VAC, KCI Medical Canada, Mississauga, Ontario, Canada), which was increased gradually from 50 mm Hg to 150 mm Hg over several weeks to facilitate healing and decrease wound size.

Outcome and follow-up

On day 67 of life, a split-thickness skin graft harvested from the right thigh was used to cover the bare area on the baby’s back. The recovery went well with a 95% gain (figure 4). The baby was eventually transferred to a level 2 hospital on nasal cannula and full gavage tube feeding at 79 days of age.