This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Radiology
[{'content': "'Bird beak' appearance on barium swallow is feature of? \nSelect and explain. \nA. Achalasia cardia, B. Diffuse esophageal spasm, C. Caustic stricture, D. Carcinoma of the esophagus", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. Achalasia cardia. (Harrison\'s Medicine, 18th ch. 292; /Fig. 292-5).Achalasia cardia- Megaesophagus/sigmoid esophagus- "Bird beak" deformity- Absence of primary peristalsis below level of cricopharyngeus- Hurst phenomenon (temporary transit through cardia when hydrostatic pressure of barium column is above toxic LES pressure)- Vigorous achalasia (numerous tertiary contractions in non-dilated distal esophagus of early achalasia).Hiatus hernia- Epiphrenic bulge- >4 longitudinal coarse thick gastric folds above gastroesophageal junction or in the suprahiatal pouch- A Schatzki or B ring if present, is pathognomonic of a hiatal hernia because it marks the junction between squamous and columnar epithelium and represents the Z line.- Distance between B ring and hiatal margin > 2 cm- Peristalsis causes above hiatus.Schatzki ring (B ring/Lower esophageal mucosal ring, seen as a thin, web-like annular constriction at the esophagogastric junction is associated with a small hiatal hernia.Lye stricture(alkali/caustic strictures) - Long, tight and smooth stricturePeptic stricture- Short and tubular narrowing.Carcinoma oesophagus- Typical annular narrowing with overhang- ing margins and destruction of the mucosa.- \'Rat-tail\' esophagus- Shouldering signLeomyoma/GIST- Smooth filling defect with right angles of origin from the esophageal wall (Submucosal smooth lesion)Cytomegalovirus esophagitis- iant ovoid flat ulcers (vasculitis of submucosal vessels)- Gastroesophageal junction with adjacent part of stomach is commonly affected.Herpes esophagitis- Discrete superficial punctate/linear serpentine/stellate/diamond shaped ulcers.Candidial esophagitis- Cobble stone mucosa- \'Shaggy\' contour of the esophagus with small diffuse superficial ulcers- Irregular plaque-like filling defectsTertiary esophageal contractions (presbyesophagus, diffuse esophageal spasm, neuromuscular diseases)- "Corkscrew" appearance- "Rosary-bead/Shish kebab" configuration- "Yo-Yo" motion of bariumScleroderma- Esophageal shortening- Sliding hiatus hernia- Hidebound esophagus', 'role': 'assistant'}]