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?

1. A

   Chondroma

2. B

   Tailgut cyst

3. C

   Epidermoid cyst

4. D

   Dermoid cyst

Appeared in: PGICH Noida NO-2025

Explanation

• A tailgut cyst, also known as a retrorectal cystic hamartoma, is a congenital lesion that arises from persistent remnants of the embryonic tailgut.
• The tailgut is the most caudal portion of the hindgut, an endoderm-derived structure, which normally regresses by the eighth week of gestation.
• Its characteristic location is the retrorectal or presacral space, precisely as described in the question stem.

Why Other Options Were Wrong

• Option A: A chondroma is a benign tumor composed of mature cartilage. Cartilage is derived from the mesoderm, not the endodermal hindgut.
• Option C: An epidermoid cyst arises from the inclusion of ectodermal tissue. It is lined by stratified squamous epithelium but lacks the skin appendages (like hair follicles) seen in dermoid cysts. Its origin is ectodermal, not endodermal.
• Option D: A dermoid cyst is a type of mature teratoma that contains tissues from multiple germ layers, but predominantly ectodermal structures like skin, hair, and sebaceous glands. It arises from pluripotent germ cells, not a specific remnant of 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 origin of retrorectal lesions as background academic context rather than a clinical decision trigger.
• While often asymptomatic and discovered incidentally, tailgut cysts can present with symptoms due to mass effect (constipation, pain) or complications.
• A key nursing consideration is the potential for complications, which include secondary infection (leading to abscesses and fistulas) and, in rare cases, malignant transformation into adenocarcinoma.
• Definitive diagnosis often requires MRI, which can show the characteristic multiloculated cystic appearance. The standard of care is complete surgical excision to prevent complications, provide a definitive histological diagnosis, and rule out malignancy.

How to Approach the Question

• First, dissect the question to identify the core concepts: a 'developmental remnant' of the 'embryological hindgut' located in the 'retrorectal space'.
• Recognize that the 'hindgut' is an endoderm-derived structure. This is the most critical clue.
• Next, evaluate each option based on its embryological origin.
• A 'Chondroma' is mesodermal (cartilage). Eliminate this option.
• 'Epidermoid' and 'Dermoid' cysts are ectodermal in origin. Eliminate these options.
• The term 'Tailgut cyst' itself points to its origin from the embryonic tailgut, which is a part of the hindgut. This makes it the only logical choice.

Concept Tested & Keywords

• Concept Tested: Embryological origin of retrorectal lesions
• Stem keywords: developmental remnant, embryological hindgut, retrorectal space, presacral space
• Lead-in keywords: most likely
• Negative lead-in flag: false

Question ID

Q8aQHsH-81HQ2Of8H2XduK

Copy ID

Reference Book

E6 PATHOLOGY QUICK REVIEWBased on Harsh Mohan Textbook of PATHOLOGY p. 232-234

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