From a mosquito bite to neonatal lupus: primary care initial diagnosis and multidisciplinary evaluation (case report)

Introduction: This clinical case demonstrates that a common lesion like an insect bite can often be much more than it appears. It also illustrates the approach taken to pathology. Case description: This case report describes a newborn who, on the 10th day of life, developed skin lesions with characteristics resembling insect bites. Three weeks later, at 45 days of life, the lesions progressed in size and dimension, leading to an urgent referral to Dermatology. The infant was admitted for a differential diagnosis, undergoing several studies, including skin biopsies and autoimmune studies. The mother’s autoimmune study revealed positive anti-SSA and anti-SSB antibodies, confirming the diagnosis of neonatal lupus. He performed topical treatment with hydrocortisone, which helped stabilize and reduce some lesions. However, after discharge, due to clinical aggravation, the infant returned to the hospital, with impetiginization of the lesions. Antibiotic therapy (topical with fusidic acid and oral with amoxicillin + clavulanic acid) was thus initiated, topical corticosteroid (hydrocortisone) reintroduced, and oral corticosteroid (deflazacort) initiated, and breast-feeding was temporarily suspended due to the presence of antibodies in breast milk (anti-SSA and anti-SSB antibodies). After five months of topical and oral corticoid, maintenance, and cessation of breastfeeding, there was significant improvement in the lesions, and the infant exhibited appropriate psychomotor development. The mother began follow-up in a Rheumatology appointment, where she was diagnosed with Sjögren’s syndrome and initiated appropriate treatment. She also received counseling regarding future pregnancies, particularly about the higher likelihood of the baby experiencing manifestations of neonatal lupus, potentially affecting other systems besides the skin. Comment: This case highlights the deceptive simplicity of the initial diagnosis and the role of a multidisciplinary team in addressing complex conditions. The family physician plays a crucial role in supporting and guiding families throughout their healthcare journey. In this case, the cessation of breastfeeding and the potential impact on future pregnancies posed additional challenges for the mother, and the family doctor played a key role in addressing her concerns and providing emotional support.