Fat necrosis of the newborn

Abstract

Introduction: Panniculitis is a group of diseases that affect subcutaneous fat tissue and clinically manifest as nodules. Its pathogenesis is not entirely clear, and it is usually asymptomatic. The confirmatory diagnosis is histological. Objective: To describe the clinical and histopathological characteristics of a case of fat necrosis, a specific form of panniculitis in the newborn (NB). Clinical Case: 40-week female NB, born by emergency cesarean section due to fetal tachycardia with meconium, Apgar score 7-8-9. She required oxygen and positive pressure for five minutes. On the fifth day of life, she presented an increased volume in the posterior trunk region, with an erythematous-purplish discoloration, which is soft and non-tender to palpation. Skin and soft tissues ultrasound showed increased echo-genicity of the subcutaneous cellular tissue and loss of definition of the adipocytes of 42.3 x 9.7 x 20.1 mm approximately, without vascularization. Skin biopsy showed epidermis with irregular acanthosis and basket-weave orthokeratosis; papillary dermis with inflammatory infiltrate, and reticular dermis and adipose tissue with presence of lymphohistiocytic infiltrate with a tendency to form nodules, without vascular involvement, and small cholesterol deposits, compatible with subcutaneous fat necrosis (SBFN) of the newborn. The patient at three months of age had complete regression of the lesion. Conclusions: a clinically and histologically compatible case with SBFN is described, that did not present complications during observation. In general, this pathology has a good prognosis, with spontaneous resolution as in our case.