Subcutaneous Fat Necrosis of the Newborn

Abstract

This is an image-based clinical vignette showing pathologic findings typical of subcutaneous fat necrosis of the newborn (SFNN). The infant—a 15-month-old girl—presented with indurated subcutaneous masses of unknown etiology. This case is a reminder that SFNN, while more common in the newborn period, can occur throughout infancy. It also reminds us that the rare metabolic disorder (Lesch–Nyhan syndrome) may be associated with lesions that can appear somewhat similar under the microscope.

Keywords

subcutaneous fat necrosis of the newborn - light polarization - gout - Lesch–Nyhan syndrome - skin nodules

Image and Case Description

This figure is a composite view from subcutaneous nodules with changes typical of “subcutaneous fat necrosis of the newborn” (SFNN) from a 15-month-old girl. It shows degenerated fat surrounded by mild infiltrates of chronic inflammation and multinucleated foreign body giant cells. Unlike in gout, no negatively birefringent needle-like crystals were seen ([Fig. 1]).

Fig. 1 Hematoxylin and eosin-stained sections showing degenerated fat surrounded by mild infiltrates of chronic inflammation and multinucleated foreign body giant cells.

Comments

Clinically, SFNN usually presents as indurated subcutaneous mass lesions. The child is usually asymptomatic at presentation with no significant past medical history or findings upon physical examination (as it was the case here).

The etiology of SFNN is not certain, but an associated hypercalcemia can be seen in more than two-thirds of cases.[1] [2]

Despite the name and predominant presentation in newborns, “SFNN” is not limited to newborn age as it can also be encountered later during infancy (our patient being 15 months old at the time of diagnosis as an example).[3]

The histologic findings of SFNN can be separated from those in gout nodules by noting that the deposited material in the latter shows birefringence under polarizing light. Gout is extremely rare in children with the rare exception of patients of Lesch–Nyhan syndrome, a metabolic disorder inherited in an X-linked mode that affects the metabolism of purines, the raw materials of deoxyribonucleic acid and ribonucleic acid. It is caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase, which is needed to recycle purines (the patient in this case was an otherwise asymptomatic girl and no birefringence was seen under polarized light).[2]

Conclusion

SFNN is not limited to the newborn age. The main differential diagnosis at the microscopic level includes gout skin nodules. Gout is extremely rare in children except in the rare metabolic disorder, Lesch–Nyhan nodules.

Conflict of Interest

None declared.

Authors' Contributions

S.B.K. made the diagnosis, wrote the first draft, and prepared the composite photo. S.S. performed literature search and edited the manuscript.

Compliance with Ethical Principles

None.

• References

• 1 Hicks MJ, Levy ML, Alexander J, Flaitz CM. Subcutaneous fat necrosis of the newborn and hypercalcemia: case report and review of the literature. Pediatr Dermatol 1993; 10 (03) 271-276
• 2 Frank L, Brandt S, Wabitsch M. Subcutaneous fat necrosis in newborns: a systematic literature review of case reports and model of pathophysiology. Mol Cell Pediatr 2022; 9 (01) 18
• 3 Mitra S, Dove J, Somisetty SK. Subcutaneous fat necrosis in newborn-an unusual case and review of literature. Eur J Pediatr 2011; 170 (09) 1107-1110

Publikationsverlauf

Artikel online veröffentlicht:
17. Februar 2025