Developmental anomolies Flashcards
(39 cards)
“What is the hair collar sign, and what does its presence suggest in the context of a scalp lesion?”
The hair collar sign is the presence of a ring of long, dark, coarse, and often radially arranged hair surrounding a congenital scalp lesion
It’s most frequently seen around:
Membranous aplasia cutis congenita (ACC)
Cephaloceles
Rudimentary meningoceles
Heterotopic neural tissue (e.g., glial heterotopia)
Its presence is a** red flag for a neural tube defect and often warrants imaging (CT/MRI) to exclude intracranial extension.**
What is a nasal dermoid cyst?
Failure of ectodermal separation from the dura during the development of the frontonasal region;
Ectodermal remnants become trapped along embryonic fusion planes -
May have a fibrous tract to dura (~25–50%) — especially when a sinus ostium is present.
Histo: Keratinizing squamous epithelium + adnexal structures (hair follicles, sebaceous glands)
What is a cephalocele?
Defective neural tube closure allows herniation of meninges and/or brain through a persistent bony defect in the skull base.
Always communicates with the intracranial compartment (by definition). Contains meninges ± brain.
What is Nasal glial heterotopia (NGH)?
Originally herniated brain tissue that becomes sequestered extracranially as the skull bones fuse around it.
No true communication, but ~15–25% have a fibrous stalk remnant extending to dura.
What are the differences between a true encephalocele and heterotopic brain tissue?
What is sinus pericranii, and how does it differ from cephaloceles and venous malformations?
a rare vascular anomaly characterized by an epicranial venous malformation that communicates directly with an intracranial dural venous sinus (usually the superior sagittal sinus) through dilated diploic veins in the skull.
What is aplasia cutis?
a clinical finding, not a single disease. It refers to the congenital absence of skin, most commonly on the scalp but potentially affecting any body region. It can present as:
An ulcer
A scar
A membranous defect
Multiple symmetric lesions
How is aplasia cutis classified?
Frieden’s Classification Scheme for ACC (1986)
Frieden classified ACC into 9 groups based on:
Anatomic site
Number of lesions
Associated anomalies
Inheritance pattern
What is Adams–Oliver Syndrome (AOS)?
A genetic multisystem developmental disorder defined by two major features:
- Aplasia Cutis Congenita (usually on the scalp)
- Terminal transverse limb defects (ranging from hypoplastic nails to limb truncation)
It can also involve:
* Dilated scalp veins
* Skull defects
* Cutis marmorata telangiectatica congenita (CMTC)
* Congenital heart defects
* CNS malformations
* Ocular anomalies
What is the inheritance of Adams Oliver Syndrome?
AD or AR
What is group 1 Aplasia Cutis Congenita?
Group 1 – Isolated Scalp ACC
Most common form
Typically membranous, located at the vertex
May show hair collar sign
No Systemic anomolies
What is group 2, Aplasia Cutis Congenita?
Group 2: ACC ass with Adam Oliver Syndrome
AR or AD condition - defect in NOTCH signalling
Leads to:
- ACC (usually scalp)
- Transverse limb defects
As well as dilated scalp veins, CMTC, cardiac and CNS defects
What is group 3 Aplasia Cutis Congenita?
Group 3 = Aplasia cutis congenita + **epidermal or Sebaceous Naevi **
- Often unilateral and localized
- ** Adjacent to epidermal nevus, nevus sebaceus, or rarely CMN**
- Part of RASopathy syndromes (mosaic mutations in HRAS/KRAS)
What is group 4 Aplasia Cutis Congenita?
ACC Overlying Embryologic Malformations
Skin absence over:
Cephaloceles, spinal dysraphism, sternal clefts, omphalocele
Often hair collar sign
Indicates an underlying malformation, not primary skin failure
What is group 5 Aplasia Cutis Congenita?
ACC from Ischemic Events
Symmetric, stellate, or angulated lesions
Usually on trunk and limbs
Linked to:
* Fetus papyraceus (twin demise)
* Placental infarction
* Vascular atresias
What is group 6 Aplasia Cutis Congenita?
ACC with Epidermolysis Bullosa (EB)
Seen in severe EB simplex, JEB, or DEB
Lesions due to fragile skin breaking down in utero
May resemble erosions or ulcers
What is group 7 Aplasia Cutis Congenita?
ACC from Mechanical or Physical Injury
Localized lesions on limbs, often linear
Related to:
* Amniotic bands
* Intrauterine trauma or compression
Think: “something slashed or constricted the roof mid-construction”
What is group 8 Aplasia Cutis Congenita?
ACC due to Teratogens, Infections, or Maternal Conditions
Teratogens: methimazole, valproate, misoprostol
Infections: herpes simplex, varicella
Maternal: antiphospholipid syndrome
What is group 9 Aplasia Cutis Congenita?
ACC Associated with Syndromes
ACC appears as one component of broader malformation syndromes:
Trisomy 13 (Patau)
Setleis syndrome
MIDAS (microphthalmia with linear skin defects)
SCALP, Oculoectodermal, UBA2-related
What are the morphological differences between membranous ACC and Irregular / Stellate ACC?
Irregular / Stellate ACC has a higher risk of dural / drain exposure and underlying brain defect.
False
List some high risk clinical features of ACC?
Midline Vertex location
Membranous quality
Hair collar sign
Pulsatility or visible blood vessels
Proximity to posterior fontanelle
Lesion > 2 -3 cm
Scalp vein dilation or varicosities
List five cutaneous markers of occult spinal dysraphism
Occult spinal dysgraphism refers to a group of congenital anomalies caused by abnormal neural tube closure, in which spinal cord, meninges, or vertebral arches fail to form or separate correctly.
- Midline Lumbosacral Dimple (Atypical)
- Hypertrichosis (Faun Tail Nevus)
- Hemangioma or Capillary Stain (Port-Wine Stain)
- Subcutaneous Lipoma or Lipomyelomeningocele
- Dermal Sinus Tract or Pits
What is LUMBAR syndrome?
LUMBAR syndrome is a neurocutaneous syndrome characterized by a segmental infantile hemangioma over the lumbosacral region that is a clue to underlying systemic anomalies — especially in mesodermal derivatives like the spine, kidneys, and genitourinary tract.
L – Lower body hemangioma (segmental)
U – Urogenital anomalies
* Includes: Hypospadias, Hydrocolpos, Urethral atresia, Cloacal malformations
M – Myelopathy
* Abnormal spinal cord development: Tethered cord, Lipomyelomeningocele, Diastematomyelia, Syringomyelia
B - Bony deformities
* Includes: Hemivertebrae, Sacral agenesis, Spina bifida occulta
A – Anorectal anomalies
* Such as: Imperforate anus, Anal stenosis, Rectovaginal/rectourethral fistula
R – Renal anomalies
* Includes: Renal agenesis, Duplicated collecting system, Vesicoureteral reflux
