Sclerema Neonatorum

Background

The classic description of sclerema neonatorum (SN) is credited to Underwood, who described it in 1784 and appropriately termed it "skinbound disease." In 1817, Alibert introduced the term sclerema, derived from the Greek word skleros, meaning hard. Sclerema neonatorum is a disorder of the subcutaneous fat in debilitated neonates and is considered best as a sign of a potentially fatal underlying disease process and not a specific disease entity.^[1] A thorough review of the nomenclature, clinical findings, histological features, differential diagnosis, and management of sclerema neonatorum was published in 2008.^[2]

The Medscape Pediatric Dermatology Resource Center may be of interest.

• References

Pathophysiology

In an infant, fat has a higher saturated-to-unsaturated fatty acid ratio compared to adult fat and thus, a higher melting point. Prematurity, hypothermia, shock, and metabolic abnormalities have been postulated to further increase this ratio, possibly as a result of enzymatic alteration allowing precipitation of fatty acid crystals within the lipocytes. This condition has been suggested to result in the dramatic clinical findings in affected skin. X-ray diffraction techniques have confirmed that infants with sclerema neonatorum have an increase in saturated fats and that the crystals within the fat cells are composed of triglycerides.^{[3, 4]}

• References

Etiology

Associated underlying conditions include pneumonia, septicemia, septic shock, hypothermia, metabolic acidosis, transient hyperammonemia of the newborn, respiratory distress syndrome, congenital heart defects, gastroenteritis, intestinal obstruction, and severe malnutrition.^{[2, 5, 6, 7]} Two case reports have described sclerema neonatorum that developed after therapeutic hypothermia initiated for neonatal asphyxia.^{[8, 9]}

• References

Epidemiology

Frequency

United States

The exact incidence of sclerema neonatorum is unknown. All studies describe sclerema neonatorum as extremely rare. The number of reported cases in recent years has declined, probably as a result of better neonatal care.

International

A 10% incidence of sclerema neonatorum was documented in preterm neonates admitted to a hospital in Bangladesh. Risk factors for developing sclerema neonatorum in these infants included poor feeding, jaundice, and bacteremia.^[10]

Race

No racial predilection has been reported.

Sex

Sclerema neonatorum shows a slight male predominance, with an estimated male-to-female ratio of 1.5:1.^[11]

Age

Sclerema neonatorum is a disease confined to the newborn period. Sclerema neonatorum can present at birth, but onset within the first week of life is more common. The oldest reported infant presented with Pseudomonas septicemia at age 106 days.

• References

Prognosis

Because sclerema neonatorum invariably is associated with serious underlying disease, the mortality rate is high. In different series, the reported mortality rates range from 67-88%, with death occurring hours to days after onset. If the underlying disease is treated successfully, the skin softens and returns to normal.

One case of an infant with consecutive episodes of sclerema was reported to occur in a severely ill infant, and both episodes resolved after appropriate treatment of underlying illness.^[12]

• References

History

Half the infants affected by sclerema neonatorum are premature, and the others are full term but have a serious underlying illness. They are often of low birth weight (Apgar scores

• References

Physical Examination

Physical findings of sclerema neonatorum appear suddenly, first on the thighs and buttocks and then, spreading rapidly, often affecting all parts of the body except the palms, soles, and genitalia. The involved skin is pale, waxy, and firm to palpation. The skin cannot be pitted or pinched up because it is bound to underlying subcutaneous tissue, muscle, and bone. The affected infant often displays flexion contractures at the elbows, knees, and hips; temperature instability; restricted respiration; difficulty in feeding; and decreased spontaneous movement. Newborns may also present with masklike facies or “pseudotrismus,” an inability to completely open the mouth, secondary to the thickening of the skin over the face, arms, and hands.^[14]

• References

Complications

Unless the underlying disease is identified and treated, the course of sclerema neonatorum is one of rapid deterioration in the general health of the infant and, ultimately, death.

• References

Laboratory Studies

Laboratory abnormalities associated with sclerema neonatorum correlate with the underlying disease process. Hypoglycemia, metabolic acidosis, respiratory alkalosis, hyperkalemia, hypocalcemia, and elevated blood urea are common, albeit nonspecific, findings. A complete sepsis workup should be initiated in all infants with sclerema neonatorum.

• References

Histologic Findings

Despite the striking clinical presentation, histologic findings of sclerema neonatorum are subtle. The subcutaneous fat may appear normal or may have only sparse inflammation, which, when present, consists of lymphocytes, histiocytes, and multinucleated giant cells. This is thought to reflect the poor immunologic response of the infant.^[15] The most consistent findings are edema, a thickening of the subcutaneous fibrous septa, and a radial array of fine, needlelike clefts in the fat cells, representing former sites of fat crystals. The lack of a granulomatous inflammation and the absence of fat necrosis help distinguish sclerema neonatorum from subcutaneous fat necrosis of the newborn (SCFN).^{[15, 16, 17]} Radially arranged needlelike clefts are common to both sclerema neonatorum and SCFN.

See the image below.

View Image

Needle-shaped crystals are arranged radially in adipocytes. Courtesy of DermNet New Zealand (https://www.dermnetnz.org/assets/Uploads/pathology/e/scle....

• References

Medical Care

Recognition and the prompt institution of therapy specific for the underlying disease are mandatory. Careful monitoring, correction of electrolyte abnormalities, respiratory support, correction of hypovolemia, and control of hypothermia are important in sclerema neonatorum patients.

Antibiotics

Some authors advocate the prompt institution of prophylactic broad-spectrum antibiotic therapy for possible associated sepsis.

Systemic steroids

The value of systemic steroids is controversial. No controlled studies have demonstrated improved survival with the use of systemic steroids in sclerema neonatorum, although they are often used and have been observed to limit the extent and development of new lesions.^{[2, 13, 18]}

Exchange transfusions

Several reports document the beneficial effect of exchange transfusions on survival.^{[1, 3, 4, 19]} A randomized controlled trial demonstrated a 50% survival rate in septic neonates with sclerema neonatorum who were treated with exchange transfusion used early in the course of the disease, compared with 5% who were not. Exchange transfusion may enhance humoral and cellular immunity in these immunologically immature neonates, and may improve peripheral and pulmonary circulation, thereby also improving oxygen exchange.^{[2, 19]}

Intravenous immunoglobulin

One case report describes the use of intravenous immunoglobulin in a neonate. There was transient improvement in the skin disease, but thoracic constriction from sclerema neonatorum ultimately led to the child's death.^[10]

• References

Consultations

Infants with sclerema neonatorum are best cared for in a neonatal intensive care unit by an intensivist.

Depending on the underlying illness (eg, sepsis), consultation to the appropriate specialists should be made.

• References

Medication Summary

Medical therapy of the skin is not beneficial; successful treatment of the underlying disorder improves the skin.

• References