A 23-year-old man with a history of eczema, allergies, and GERD presents with intermittent dysphagia at a gastroenterology clinic. His dysphagia, occurring about 50% of the time with solid foods (especially large pieces), has progressively worsened over the past year. Initially managed with waiting or carbonated beverages, now food consistently remains lodged, causing chest pain and occasional vomiting. Several months ago, he experienced an episode where food felt stuck for up to 3 hours before spontaneously clearing. His GERD symptoms (heartburn and regurgitation) have also worsened recently despite famotidine 20 mg daily. He has no history of surgeries or significant medical issues, and he leads a healthy lifestyle with no smoking, drug use, or excessive alcohol consumption. His blood pressure is 112/74 mm Hg, pulse 70 beats/min, respiration rate 12 breaths/min, temperature 98.6°F (37°C), and oxygen saturation 98% on room air. His body mass index (BMI) is 24.3 kg/m². The physical exam is largely normal except for an erythematous, vesicular rash on his hands and arms. The laboratory workup reveals the following values:
Hemoglobin                                                      140 g/L (125–170)
White blood cell count                               9.3 × 109/L (3.5–10.5)
Platelet count                                                  295× 109/L (130–380)
Absolute neutrophil count                              4.1× 109/L (2.0–7.5)
Absolute lymphocyte count                             2.7× 109/L (0.8–3.3)
Absolute monocyte count                                     0.6 × 109/L (0.1–1.0)
Absolute eosinophil count                                     1.5 × 109/L (0–0.5)
Absolute basophil count                                        0.07× 109/L (0–0.1)
An upper endoscopy was performed due to persistent symptoms, revealing mucosal changes with rings and longitudinal furrows throughout the esophagus, but no esophageal ulcers, exudates, strictures, or bleeding were observed.