This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General surgery, Subject name: Surgery
Flask shaped undermined ulcers in rectosigmoid area are seen in 
Select and explain. 
A. Amoebiasis, B. Typhoid, C. Tuberculosis, D. Hydatid disease
A: Amoebiasis
Answer: A: Amoebiasis 
Explanation: Most amoebic ulcers occur in the rectosigmoid. On sigmoidoscopy shallow skip lesions and 'flaskshaped' or 'collar-stud' undermined ulcers may be seen and can be biopsied or scrapings can be taken along with mucus for immediate microscopic examination. The presence of trophozoites distinguishes the condition from ulcerative colitis.Ref: Bailey and Love 27e pg: 58