Eosinophilic Esophagitis in a 3-Year-Old Girl with Spinal Muscular Atrophy Type 1: The First Reported Case.

Background: Spinal muscular atrophy type 1 (SMA1) is a severe neuromuscular disorder characterized by progressive muscle weakness and atrophy, including the muscles of the oral cavity and esophagus. Eosinophilic esophagitis (EoE), a chronic, allergic disease, presents with eosinophilic infiltration of the esophagus, leading to esophageal dysmotility. Feeding difficulties may occur in both conditions. So far, the coexistence of EoE and SMA1 has not been described; we present the first such case. Case presentation: The patient was a girl with SMA1 diagnosed shortly after birth, treated with nusinersen and onasemnogene abeparvovec, and fed a standard industrial diet through a gastrostomy. In her second year of life, she developed increasing symptoms: distress during feeding, regurgitation, vomiting, and weight loss. She was treated with proton pump inhibitors without clinical improvement. Gastroscopy was performed, revealing superficial epithelial damage with bleeding in the proximal esophagus. Histopathology showed chronic inflammation with up to 150 eosinophils per high-power field, microabscesses, spongiosis, and basal layer hypertrophy. The girl was diagnosed with EoE. Her diet was switched from a standard industrial formula to an amino acid-based formula, which led to marked clinical improvement, the resolution of symptoms, and appropriate weight gain. Conclusions: This case report highlights the challenges of diagnosing EoE in SMA1 patients and emphasizes the need for multidisciplinary approaches and further investigation of allergic manifestations in SMA1 patients.