47: The Ichthyoses Flashcards
1
Q
What is the hallmark of ichthyosis and what does it reflect?
A
Generalized scaling is the hallmark of ichthyosis, reflecting altered differentiation of the epidermis.
2
Q
What are the primary criteria for classifying ichthyoses according to the revised nomenclature?
A
The primary criteria for classification include whether the disorder is limited to the skin (nonsyndromic) or affects the skin and other organ systems (syndromic), its mode of inheritance, and disease pathobiology.
3
Q
What are the important features in distinguishing different forms of ichthyosis?
A
Important features include:
- Age of onset
- Presence of collodion membrane at birth
- Quality of scale
- Presence or absence of erythroderma
- Abnormalities in other parts of the skin and adnexal structures.
4
Q
What is the significance of genetic analysis in ichthyosis?
A
Genetic analysis can support clinical diagnosis and may indicate the presence of ichthyosis in adulthood as a marker of systemic disease.
5
Q
What are the common tests used to determine underlying genetic defects in ichthyosis?
A
Common tests include:
- Fetoscopy, fetal skin biopsy - late in pregnancy
- CVS (Chorionic Villus Sampling) - 10-12 weeks
- Amniocentesis - second trimester
- Mutational analysis
- Preimplantation genetic diagnosis
- Carrier detection for at-risk relatives for AR disorders in which mutation is known.
6
Q
What are the two main categories of ichthyosis based on genetic inheritance?
A
The two main categories are:
- Autosomal Dominant (AD) diseases - high frequency of spontaneous/de novo mutations.
- Autosomal Recessive (AR) diseases - often associated with paternal consanguinity.
7
Q
What are the primary functions of keratinocytes in the epidermis?
A
Keratinocytes serve as the primary cell type of the epidermis, providing resilience and water retention, acting as a barrier to mechanical trauma and desiccation, and undergoing regular differentiation.
8
Q
What are the common therapeutic approaches for managing ichthyosis?
A
The common therapeutic approaches for ichthyosis include:
- Hydration - Softens skin surface, especially in moist climates and with long baths.
- Lubrication - Prolongs hydration and softening, using bath oils or lubricants before drying.
- Keratolysis - Enhances corneocyte desquamation to remove scale and thin hyperkeratotic stratum corneum using keratolytic creams and lotions containing urea, salicylic acid, or alpha-hydroxy acids.
9
Q
What is the clinical presentation of ichthyosis vulgaris?
A
Ichthyosis vulgaris typically manifests within the first year of life, with scaling most prominent on extensor surfaces of extremities, sparing flexural and diaper areas. The scaling may be centrally attached, with ‘cracking’ at the edges.
10
Q
What genetic mutations are associated with autosomal recessive congenital ichthyosis?
A
Genetic mutations associated with autosomal recessive congenital ichthyosis include:
- Transglutaminase-1: Catalyzes cross-linking of proteins and attachment of ceramides during corneocyte formation.
- Netherton syndrome (SPINK5): Encodes a serine protease inhibitor involved in normal epidermal differentiation.
- Filaggrin (FLG): Results in reduced or absent filaggrin and decreased moisture binding in the stratum corneum.
11
Q
What is the role of filaggrin in the skin barrier function?
A
Filaggrin is an epidermal protein that aggregates keratin intermediate filaments and retains moisture in the stratum corneum. It is synthesized as a high-molecular-weight precursor, profilaggrin, and is crucial for maintaining the integrity of the skin barrier.
12
Q
A patient with ichthyosis vulgaris has a severe phenotype. What genetic mutation is likely responsible, and how does it affect the skin?
A
The severe phenotype is likely due to mutations in both profilaggrin alleles (homozygotes or compound heterozygotes). This results in reduced or absent filaggrin, leading to decreased moisture binding in the stratum corneum.
13
Q
How does the absence or decrease of filaggrin contribute to the clinical features of ichthyosis vulgaris?
A
The absence or decrease of filaggrin leads to:
- Impaired aggregation of keratin intermediate filaments, resulting in reduced moisture retention in the stratum corneum.
- Keratinocytes maturing into corneocytes may not properly collapse and cross-link, affecting the integrity of the cornified cell envelope.
- This contributes to the characteristic scaling and dryness seen in ichthyosis vulgaris, as well as associations with atopic dermatitis due to compromised barrier function.
14
Q
What are the clinical features of ichthyosis vulgaris, and how do they manifest in patients?
A
Clinical features of ichthyosis vulgaris include:
- Onset within the first year of life.
- Scaling most prominent on extensor surfaces of extremities, with sparing of flexural and diaper areas.
- Scaling may be centrally attached, often leading to cracking at the edges.
- Patients may exhibit a mild phenotype if they carry one mutated allele, while those with mutations in both profilaggrin alleles may present with a severe phenotype.
15
Q
What role do genetic mutations play in the pathogenesis of ichthyosis, particularly in relation to keratin and filaggrin?
A
Genetic mutations involved in ichthyosis include:
- Keratin 1 and 10 mutations: Affect the polymerization of keratin intermediate filaments, leading to compromised skin barrier function.
- Transglutaminase-1 mutations: Disrupt the cross-linking of proteins and attachment of ceramides, affecting corneocyte formation.
- Filaggrin (FLG) mutations: Result in reduced moisture binding in the stratum corneum, contributing to dryness and scaling.
These mutations collectively impair the skin’s barrier function, leading to the clinical manifestations of ichthyosis.
16
Q
What are the clinical features of X-linked recessive ichthyosis (XLI)?
A
- May begin in the newborn period
- Scaling, more prominent on extensors
- Hyperlinear palms and soles
- Comma-shaped corneal opacities
- Increased risk of cryptorchidism and testicular cancer
17
Q
What is the etiology of X-linked recessive ichthyosis (XLI)?
A
- Absence/Decrease in Steroid Sulfatase (Arylsulfatase C) enzyme activity
- Steroid sulfatase hydrolyzes sulfate esters, inhibiting proteases that degrade corneodesmosomes
- High serum cholesterol levels noted in many cases
18
Q
What are the management strategies for X-linked recessive ichthyosis (XLI)?
A
- Long bathwater soaks for prominent scaling
- Emollients to manage skin condition
19
Q
What are the clinical features of a collodion baby?
A
- Present at birth with red, scaly skin
- Encased in a translucent, parchment-like membrane
- May impair respiration and sucking
- Membrane breaks up and peels off during the first 2 weeks of life
20
Q
What is the etiology and pathogenesis of collodion baby presentations?
A
- In utero aqueous environment contributes to collodion presentation
- An AR self-healing collodion phenotype described, where skin clears within weeks
- Mutations in ALOX12B, ALOX3E, or TGM1.
21
Q
What management strategies are recommended for collodion babies?
A
- Newborn care including monitoring for infection, temperature, hydration, and electrolytes
- Pain management and eye care
- Use of humidified incubator and wet compresses to hydrate the membrane
- Release of constricting bands via curettage or debridement to prevent complications
22
Q
A patient with ichthyosis has generalized scaling, sparing the flexural areas, and hyperlinear palms. What is the diagnosis, and what environmental factors worsen the condition?
A
The diagnosis is Ichthyosis Vulgaris. The condition worsens in dry, cold environments and improves in warm, humid environments.
23
Q
A patient with ichthyosis has a history of prolonged labor and corneal opacities. What is the likely diagnosis, and what enzyme deficiency is involved?
A
The likely diagnosis is X-linked Recessive Ichthyosis (XLI), caused by a deficiency in the steroid sulfatase enzyme.
24
Q
What are the clinical features that distinguish X-linked recessive ichthyosis (XLI) from ichthyosis vulgaris?
A
XLI may begin in the newborn period and presents with scaling that is more prominent on extensors. In contrast to ichthyosis vulgaris, XLI shows more severe involvement with larger scale, comma-shaped corneal opacities, and affected males have an increased risk of cryptorchidism and testicular cancer.
25
What is the significance of steroid sulfatase enzyme activity in the etiology of X-linked recessive ichthyosis?
The absence or decrease in steroid sulfatase (Arylsulfatase C) enzyme activity leads to the accumulation of sulfate esters, which are crucial for the degradation of corneodesmosomes. This deficiency is detected in many tissues and is responsible for the clinical manifestations of XLI.
26
How does the management of a collodion baby differ from that of a newborn with X-linked recessive ichthyosis?
Management of a collodion baby includes monitoring for infection, hydration, and electrolytes, along with pain management and eye care. A humidified incubator and wet compresses are used to hydrate the membrane. In contrast, management of XLI focuses on long bathwater soaks and emollients for scaling.
27
What are the potential complications associated with the management of a collodion baby?
Complications can arise from the membrane breaking up and peeling off, which may leave fissures that impair the barrier to infection and water loss. Additionally, constricting bands may require release via curettage or debridement to prevent further complications.
28
What are the associated findings in X-linked recessive ichthyosis that may indicate overlap syndromes?
Associated findings in XLI include genetic deletions that involve STS and adjacent sulfatases, which can explain overlap syndromes such as chondrodysplasia punctata. Additionally, XLI is linked with conditions like Kallmann syndrome, characterized by hypogonadotropic hypogonadism and anosmia.
29
What are the clinical features of Lamellar Ichthyosis (LI) phenotype?
- Apparent at birth
- Encased in a collodion membrane
- Red skin at birth with large platelike scales, largest over lower extremities
- Resembles appearance of 'dry riverbed'
- Commonly associated mutation in TGM1 gene
- Scarring alopecia, most marked at periphery
- Bathing suit ichthyosis: scaling typical of LI but limited to bathing suit area; decreased transglutaminase; unique temperature-sensitive mutations in TGM1 have been identified.
30
What distinguishes Congenital Ichthyosiform Erythroderma (CIE) from Lamellar Ichthyosis (LI)?
- CIE is apparent at birth and encased in a collodion membrane.
- CIE presents with red skin even after shedding of the membrane, usually with a fine, white, generalized scale.
- Unlike LI, CIE does not typically present with ectropion, eclabium, or alopecia.
31
What are the key characteristics of Harlequin Ichthyosis phenotype?
- Dramatic, severe, and sometimes fatal presentation of ichthyosis.
- Premature birth with thick, shiny plates of stratum corneum separated by deep, red fissures that form geometric patterns.
- Poorly developed ears.
- Ectropion and eclabium are present.
- Tapered fingernails with hyperconvexity of nails.
32
What genetic mutations are associated with Autosomal Recessive Congenital Ichthyosis?
Mutations in the following genes are important for the formation of the intercellular lipid layer/cornified envelope of keratinocytes:
- TGM1
- ALOX12B
- ALOXE3
- NIPAL4
- CYP4F22
- ABCA12
- PNPLA1
- CERS3
- SDR9C7
- SULT2B1
33
What is the significance of the TGM1 gene in Lamellar Ichthyosis?
The TGM1 gene is commonly associated with Lamellar Ichthyosis (LI) phenotype, where mutations in this gene lead to the characteristic features of the condition, including the appearance of large, dark, platelike scales and scarring alopecia.
34
A newborn presents with a collodion membrane and red skin that transitions into large, dark, platelike scales. What is the likely diagnosis and associated mutation?
The likely diagnosis is Lamellar Ichthyosis.
35
What is the likely diagnosis and associated mutation for a newborn with a collodion membrane and red skin transitioning into large, dark, platelike scales?
The likely diagnosis is Lamellar Ichthyosis (LI), commonly associated with mutations in the TGM1 gene.
36
What syndrome is characterized by ichthyosis, structural hair shaft abnormalities, and atopy?
This is Netherton syndrome, caused by mutations in the SPINK5 gene, which encodes a serine protease inhibitor.
37
What is the diagnosis for a newborn with ichthyosis characterized by thick, shiny plates of stratum corneum separated by deep fissures?
The diagnosis is Harlequin Ichthyosis, caused by mutations in the ABCA12 gene.
38
What are the key clinical features of Lamellar Ichthyosis (LI) phenotype?
- Apparent at birth
- Encased in a collodion membrane
- Red skin at birth with large platelike scales, largest over lower extremities
- Resembles appearance of 'dry riverbed'
- Commonly associated mutation in **TGM1**
- Scarring alopecia, most marked at periphery
- Bathing suit ichthyosis, limited to bathing suit area with decreased transglutaminase
39
How does Congenital Ichthyosiform Erythroderma (CIE) phenotype differ from Lamellar Ichthyosis (LI)?
- Both are apparent at birth and encased in a collodion membrane.
- CIE presents with red skin even after shedding of the membrane, usually with a fine, white, generalized scale.
- CIE is characterized by the absence of ectropion, eclabium, and alopecia, which may be present in LI.
40
What are the genetic mutations associated with Autosomal Recessive Congenital Ichthyosis?
The condition is caused by mutations in 10 genes important for the formation of the intercellular lipid layer/cornified envelope of keratinocytes:
- **TGM1**
- **ALOX12B**
- **ALOXE3**
- **NIPAL4**
- **CYP4F22**
- **ABCA12**
- **PNPLA1**
- **CERS3**
- **SDR9C7**
- **SULT2B1**
41
What are the clinical features of Harlequin Ichthyosis phenotype?
- Dramatic, severe, and sometimes fatal presentation of ichthyosis.
- Premature birth with thick, shiny plates of stratum corneum separated by deep, red fissures.
- Poorly developed ears.
- Ectropion and eclabium present.
- Tapered fingernails with hyperconvexity.
- Resembles the patched costumes of harlequin clowns.
42
What is Netherton syndrome and its associated features?
Netherton syndrome is an autosomal recessive disorder characterized by:
- Ichthyosis and structural hair shaft abnormalities.
- **Ichthyosis linearis circumflexa**: Polycyclic, serpiginous, migratory, double-edged scale at margins of erythematous plaques.
- **Trichorrhexis invaginata**: Hair shaft abnormality where the distal hair segment telescopes into the proximal one.
- Atopy-like diathesis: Atopic dermatitis, asthma, or severe food allergy with marked IgE elevation.
43
What are the characteristic clinical features of Autosomal Dominant ichthyosis vulgaris?
- Fine or coarsely scaled down skin with superficial fissuring affecting palms and soles.
- Keratosis pilaris, atopy, and frequent skin infections are common.
44
What is the genetic basis of Erythrokeratodermia variabilis?
Erythrokeratodermia variabilis is associated with mutations in the **GJB3** and **GJB4** genes, which encode for connexins involved in intercellular communication.
45
What are the associated features of X-linked recessive ichthyosis?
- Corneal opacities on the posterior capsule.
- Cryptorchidism in males, which may lead to delayed progression of puberty.
46
What is the function of the protein encoded by the **FLG** gene in ichthyosis vulgaris?
The **FLG** gene encodes for **filaggrin**, which aggregates keratin filaments and is crucial for maintaining the skin barrier function.
47
What are the clinical features of Chondrodysplasia punctata, X-linked dominant type?
- Characterized by linear hyperkeratosis, follicular atrophies, and skeletal abnormalities.
- Associated with cataracts and deafness.
48
What are the characteristic clinical features of Autosomal Dominant Ichthyosis Vulgaris and its associated gene?
**Characteristic Clinical Features:** Keratosis pilaris, atopy, and hyperlinear palms and soles.
**Associated Gene:** FLG (filaggrin)
**Function:** Uncertain; may aggregate keratin filaments and be a precursor to stratum corneum barrier dysfunction.
49
How does the inheritance pattern affect the clinical presentation of X-linked recessive ichthyosis?
**Clinical Presentation:** Fine to large scales, comma-shaped corneal opacities on the posterior capsule.
**Associated Gene:** STS (steroid sulfatase)
**Function:** Abnormal cholesterol metabolism, leading to issues with cholesterol biosynthesis.
50
What are the distinguishing features of Erythrokeratodermia Variabilis and its genetic implications?
**Characteristic Clinical Features:** Generalized hyperkeratosis and erythroderma with patches.
**Associated Gene:** GJB3, GJB4
**Function:** Abnormal intercellular communication, leading to variable skin presentations.
51
What are the associated features and genetic implications of Chondrodysplasia Punctata in X-linked inheritance?
**Characteristic Clinical Features:** May begin as erythroderma, linear-whorled ichthyosis, or hyperkeratosis.
**Associated Features:** Cataracts, deafness.
**Associated Gene:** ARSE (arylsulfatase E)
**Function:** Lipid metabolism; failure of hydrolysis of sulfate esters.
52
What are the characteristic clinical features of Ichthyosis prematurity syndrome?
- **Premature delivery** of infants with
- **Erythematous** dermatosis,
- **Transitional epidermis** with scaling,
- **Respiratory distress** due to transient respiratory distress syndrome.
53
What gene is associated with Harlequin ichthyosis and what is its functional effect?
- **Gene**: ABCA12
- **Functional Effect**: ATP-binding cassette, subfamily A, member 12, involved in lipid metabolism and membrane transport.
54
What are the associated features of Neetsham syndrome?
- **Associated Features**:
- Ichthyosis resembling ichthyosis vulgaris
- Short stature
- Squires
- May have immunologic failure to thrive.
55
What is the onset and characteristic clinical feature of Bifidum disease?
- **Onset**: Ichthyosis develops years after birth.
- **Characteristic Clinical Features**: Progressive neurologic dysfunction, skeletal, cardiac, and renal anomalies.
56
What is the genetic basis of Trichothiodystrophy and its associated features?
- **Genetic Basis**: X-linked recessive inheritance.
- **Associated Features**:
- Brittle hair, photosensitivity, short stature, intellectual impairment, microcephaly, recurrent infections.
57
What are the characteristic clinical features of Harlequin ichthyosis and its associated genetic factors?
**Characteristic Clinical Features:**
- Severe, generalized scaling
- Erythroderma
- Associated with **genetic defects** in the ABCA12 gene.
**Associated Features:**
- Restricted respiratory function
- Neonatal death due to respiratory failure
**Gene:** ABCA12
**Function or Functional Effect:**
- ATP-binding cassette, subfamily A, member 12, involved in lipid metabolism.
58
Describe the clinical presentation and genetic implications of Ichthyosis prematurity syndrome.
**Clinical Presentation:**
- Premature delivery of infants
- Erythrodermic dermatitis
- Transient epidermolysis
- Scaly skin with respiratory distress
**Associated Features:**
- Respiratory distress due to skin involvement
**Gene:** KRT17
**Function or Functional Effect:**
- Fatty acid transport protein involved in lipid metabolism.
59
What are the distinguishing features of Neetshorne syndrome and its genetic basis?
**Distinguishing Features:**
- Ichthyosis with **congenital** defects
- Short stature and **sparse hair**
**Associated Features:**
- Above average skin surface levels of **squalene**
**Gene:** SPINK5
**Function or Functional Effect:**
- LEKTI serine protease inhibitor, which may influence skin barrier function.
60
Explain the clinical significance of Bifidum disease and its associated genetic factors.
**Clinical Features:**
- Ichthyosis develops years after birth
- Progressive neurological dysfunction
**Associated Features:**
- Retinitis pigmentosa
- Elevated plasma phytanic acid
**Gene:** Most commonly associated with **PAX6**
**Function or Functional Effect:**
- Phytanoyl-CoA hydroxylase deficiency, leading to abnormal phytanic acid metabolism.
61
What are the clinical implications of Trichothiodystrophy and its genetic associations?
**Clinical Features:**
- Generalized scaling
- Brittle hair, photosensitivity
- Short stature and intellectual impairment
**Associated Features:**
- Severe pruritus, hepatic abnormalities
**Gene:** ABHDS
**Function or Functional Effect:**
- Abhydrolase domain-containing protein 5, involved in lipid metabolism.
62
What are the inheritance patterns associated with Epidermolysis bullosa simplex and what gene is involved?
Epidermolysis bullosa simplex has an **autosomal dominant (AD)** inheritance pattern and is associated with the **KRT5** and **KRT14** genes.
63
Which ichthyosis is linked to the gene ABCA12 and what is its inheritance pattern?
The ichthyosis linked to the **ABCA12** gene is **Harlequin ichthyosis**, which has an **autosomal recessive (AR)** inheritance pattern.
64
What is the inheritance pattern and associated gene for Lamellar ichthyosis?
Lamellar ichthyosis has an **autosomal recessive (AR)** inheritance pattern and is associated with the **TGM1** gene.
65
Identify the ichthyosis associated with the gene CDSN and its inheritance pattern.
The ichthyosis associated with the **CDSN** gene is **Generalized peeling skin disease**, which has an **autosomal recessive (AR)** inheritance pattern.
66
What is the inheritance pattern for X-linked ichthyosis and which gene is involved?
X-linked ichthyosis has an **X-linked recessive (XLR)** inheritance pattern and is associated with the **STS** gene.
67
What are the inheritance patterns associated with Epidermolysis bullosa simplex and its related gene mutations?
Epidermolysis bullosa simplex is inherited in an **autosomal dominant (AD)** manner and is associated with mutations in the **KRT5** and **KRT14** genes.
68
How does the inheritance of Lamellar ichthyosis differ from that of X-linked ichthyosis?
Lamellar ichthyosis is inherited in an **autosomal recessive (AR)** manner, while X-linked ichthyosis is inherited in an **X-linked recessive (XLR)** manner.
69
What is the role of the gene ABCA12 in the context of ichthyosis?
The gene **ABCA12** is associated with **lamellar ichthyosis** and is inherited in an **autosomal recessive (AR)** manner, indicating its critical role in lipid transport and skin barrier function.
70
Identify the cellular defect associated with the disease 'Harlequin ichthyosis' and its inheritance pattern.
Harlequin ichthyosis is associated with a defect in the **cornified envelope** and is inherited in an **autosomal recessive (AR)** manner.
71
What distinguishes the genetic basis of ichthyosis vulgaris from that of X-linked recessive ichthyosis?
Ichthyosis vulgaris is primarily caused by mutations in the **filaggrin gene (FLG)** and follows an **autosomal dominant (AD)** inheritance pattern, whereas X-linked recessive ichthyosis is linked to mutations in the **steroid sulfatase gene (STS)** and follows an **X-linked recessive (XLR)** inheritance pattern.
72
What is the role of the TGM1 gene in lamellar ichthyosis (LI) phenotypes?
The **TGM1** gene encodes **transglutaminase 1**, which catalyzes **calcium-dependent cross-linking** of proteins during the formation of the stratum corneum.
73
What are the clinical features of Harlequin ichthyosis?
Harlequin ichthyosis is characterized by:
- **Autosomal recessive inheritance** of mutations in the **ABCA12** gene, which is involved in lamellar granule secretion and epidermal lipid transport.
74
What is Netherton syndrome and its associated genetic mutation?
Netherton syndrome is caused by mutations in the **SPINK5** gene, which encodes **LEKTI**, a serine protease inhibitor.
75
How do clinical features aid in the diagnosis of lamellar ichthyosis (LI) and congenital ichthyosiform erythroderma (CIE)?
The diagnosis of LI and CIE is primarily based on clinical features and history, which include:
- Presentation with a **collodion membrane** at birth that sheds to reveal either the thick, adherent scale of LI or the erythroderma and finer scale of CIE.
76
What is the role of the mutated protein in a patient with ichthyosis and mutations in the SPINK5 gene?
The mutated protein, LEKTI, is a serine protease inhibitor that prevents premature desquamation by inhibiting proteases that degrade corneodesmosomes.
77
What is the role of the mutated protein in SPINK5 gene mutations?
The mutated protein, LEKTI, is a serine protease inhibitor that prevents premature desquamation by inhibiting proteases that degrade corneodesmosomes.
78
What is the role of transglutaminase 1 in the formation of the stratum corneum?
Transglutaminase 1 catalyzes the cross-linking of cellular proteins during the formation of the stratum corneum, facilitating processes such as cross-linking of proteins, depositing the protein complex on the plasma membrane, and attaching ceramides to cornified envelope proteins.
79
How do mutations in ABCA12 contribute to Harlequin ichthyosis?
Mutations in ABCA12 lead to Harlequin ichthyosis by causing autosomal recessive inheritance, impaired secretion of lamellar granules, absence of normal lamellar granules, and no formation of lipid lamellae between granular and cornified cells.
80
What is the significance of LEKTI in Netherton syndrome?
LEKTI, encoded by the SPINK5 gene, acts as a serine protease inhibitor, inhibiting proteases that degrade the corneodesmosome, allowing for premature desquamation and is associated with atopy and atopic dermatitis.
81
What are the clinical features of lamellar ichthyosis and congenital ichthyosiform erythroderma at birth?
At birth, they typically present with a collodion membrane that sheds to reveal either thick, adherent scale characteristic of lamellar ichthyosis or erythroderma and finer scale associated with congenital ichthyosiform erythroderma.
82
What are the clinical features of Harlequin ichthyosis?
Harlequin ichthyosis presents with armor-like plates of scale, deep fissures at birth, severe erythroderma and scaling after shedding of scales, and risks of abnormal water loss, poor temperature regulation, fluid and electrolyte imbalance, and infection.
83
What is Netherton syndrome and its clinical presentation at birth?
Netherton syndrome is characterized by hair shaft abnormalities, generalized erythroderma at birth, possible atopic features, and increased risk for systemic toxic effects due to an abnormal skin barrier.
84
How do oral retinoids affect patients with Lamellar Ichthyosis?
Oral retinoids can improve or prevent sequelae of Lamellar Ichthyosis and cause side effects like blepharitis or conjunctivitis but are usually well tolerated.
85
What are the key features of Epidermolytic Ichthyosis?
Epidermolytic Ichthyosis is characterized by vacuolar degeneration of the epidermal keratinocyte leading to epidermal lysis, associated hyperkeratosis, and presentation at birth with blistering, redness, and peeling.
86
What are the implications of using topical agents in patients with Netherton syndrome?
Topical agents may require monitoring of serum levels due to increased absorption and risk of systemic effects, while topical and systemic retinoids should be avoided as they can exacerbate the condition.
87
What is the diagnosis for a newborn with ichthyosis presenting with blistering and redness?
The diagnosis is Epidermolytic Ichthyosis (EI), characterized by vacuolar degeneration of the epidermal keratinocyte and associated hyperkeratosis.
88
What is the likely diagnosis for a patient with ichthyosis and erythroderma that improves with systemic retinoids?
The likely diagnosis is Lamellar Ichthyosis or Congenital Ichthyosiform Erythroderma. Retinoids reduce hyperkeratosis and facilitate desquamation.
89
What is the diagnosis for a patient with ichthyosis presenting with armor-like plates of scale?
The diagnosis is Harlequin Ichthyosis. Systemic retinoids can facilitate desquamation and improve outcomes.
90
What are the clinical features and management considerations for Harlequin ichthyosis in neonates?
- Clinical Features: Armor-like plates of scale, deep fissures, risk of abnormal water loss, poor temperature regulation, and erythroderma after shedding.
- Management Considerations: Systemic retinoids facilitate desquamation, supportive care for feeding issues, and monitoring for infection.
91
How does Netherton syndrome present at birth?
- Presentation at Birth: Generalized erythroderma, with some individuals having persistent erythroderma or fading with inflammatory lesions.
- Implications for Treatment: Caution with topical agents, avoidance of retinoids, and monitoring serum levels.
92
What are the key clinical features of epidermolytic ichthyosis?
- Key Clinical Features: Vacuolar degeneration of the epidermal keratinocyte, blistering, redness, peeling, and hyperkeratosis.
- Differentiation: Histopathologic examination reveals epidermal lysis, with presentation typically at birth.
93
What are the clinical features of Linear Ichthyosiform Erythroderma?
- Striking clinical heterogeneity with phenotypes including thick palmoplantar hyperkeratosis, generalized spiny scale, and migratory patches of erythrokeratoderma.
94
What is the genetic basis of Linear Ichthyosiform Erythroderma?
Linear EI results from somatic mutations in the genes KRT1 and KRT10, identical to those found in generalized ichthyosis.
95
What are the characteristics of Superficial Epidermolytic Ichthyosis?
- SIE is a rare autosomal dominant genodermatosis, presenting with redness and blistering that subsides over weeks to months, developing corrugated hyperkeratosis.
96
What is the clinical presentation of Annular Epidermolytic Ichthyosis?
Annular Epidermolytic Ichthyosis presents at birth or within the first few months with severe, intermittent scaling and blistering that resolves during puberty.
97
What are the clinical implications of generalized hyperkeratosis in patients with erythroderma?
Generalized hyperkeratosis may develop, leading to a characteristic odor due to superinfection. Management includes topical and systemic antibiotics.
98
How does Linear Ichthyosiform Erythroderma present?
It presents in a linear mosaic pattern along Blaschko lines, with areas of hyperkeratosis alternating with normal skin, associated with somatic mutations in KRT1 and KRT10.
99
What are the distinguishing features of Superficial Epidermolytic Ichthyosis?
Characterized by fragility of the epidermis, leading to loss of the uppermost epidermis and development of corrugated hyperkeratosis, particularly in flexural areas.
100
What are the clinical features and progression of Annular Epidermolytic Ichthyosis?
Annular Epidermolytic Ichthyosis is characterized by severe, intermittent scaling and blistering that typically resolves during puberty, requiring monitoring and management.
