Q6. A developmental remnant of the embryological hindgut persisting in the retrorectal (presacral) space is most likely to give rise to which of the following lesions?

A. Chondroma

B. Tailgut cyst

C. Epidermoid cyst

D. Dermoid cyst

1. A

   A. Chondroma

2. B

   B. Tailgut cyst

3. C

   C. Epidermoid cyst

4. D

   D. Dermoid cyst

Appeared in: INI-CET EXAM -2026

Explanation

• The question asks for a lesion originating from a hindgut remnant in the retrorectal space.
• The tailgut is a transient, caudal extension of the embryonic hindgut.
• A tailgut cyst (retrorectal cystic hamartoma) forms when this embryonic tailgut fails to completely regress.
• This makes it the only option directly derived from a hindgut remnant.

Why Other Options Were Wrong

• Option A: A chondroma is a benign tumor of cartilage, which originates from the mesoderm, not the endodermal hindgut.
• Option C: An epidermoid cyst arises from ectodermal tissue that becomes trapped during embryonic development. It is lined by squamous epithelium but is not of hindgut origin.
• Option D: A dermoid cyst is a type of teratoma also originating from the ectoderm. It contains skin appendages like hair follicles and glands. While it can occur in the presacral space, its origin is not the hindgut.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Embryological remnants and associated pathologies as background academic context rather than a clinical decision trigger.
• While many tailgut cysts are asymptomatic and found incidentally, nurses should be aware of potential symptoms like rectal pain, constipation, or signs of infection in the perianal area, which could indicate an underlying retrorectal mass.
• The primary treatment is surgical excision due to the risk of infection, abscess formation, and malignant transformation. Post-operative nursing care would focus on wound management, pain control, and monitoring for signs of infection or recurrence.
• What if? If a patient presents with a draining sinus or recurrent abscess in the sacrococcygeal area, a tailgut cyst should be considered in the differential diagnosis along with more common conditions like pilonidal cysts. An MRI would be crucial to differentiate these conditions and plan the correct surgical approach.

How to Approach the Question

• First, identify the key phrases in the question: 'embryological hindgut' and 'retrorectal (presacral) space'.
• The question requires knowledge of embryology and the origins of different types of cysts and tumors.
• Evaluate each option based on its germ layer origin.
• Recall or deduce that 'Chondroma' is from mesoderm (cartilage) and 'Epidermoid/Dermoid' cysts are from ectoderm (skin elements).
• The term 'Tailgut cyst' itself provides a strong clue, linking it directly to the 'tailgut', which is the caudal-most part of the embryonic hindgut.
• Conclude that the tailgut cyst is the only lesion listed that originates from a hindgut remnant.

Concept Tested & Keywords

• Concept Tested: Embryological remnants and associated pathologies
• Stem keywords: developmental remnant, embryological hindgut, retrorectal space, presacral space
• Lead-in keywords: most likely

Question ID

Ql_5zMlSQwEd5NcC8dJWj5

Copy ID

Reference Book

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 1093-1095

E6 Obstetrics Williams p. 64-85