77: Hypermelanoses Flashcards
(307 cards)
What are the clinical features of congenital linear and whorled nevoid hypermelanosis?
Widespread streaky hyperpigmented macules along Blaschko lines; typically located on trunk and extremities; does not cross the midline; spares the face, palms, soles, eyes, and mucous membranes; may fade with advancing age.
What are the four clinical phases of Incontinentia Pigmenti?
- Vesicular stage (from birth or shortly thereafter); 2. Verrucous stage (between week 2 and 8); 3. Hyperpigmented stage (several months of age into adulthood); 4. Hypopigmented stage (from infancy onwards).
What is the etiology of Incontinentia Pigmenti?
X-linked dominant disorder; caused by mutation in the IKBKG gene (previously NEMO); lethal in male embryos; in females, inactivation of one of the two X chromosomes occurs during embryogenesis.
What are the extraneous manifestations associated with congenital linear and whorled nevoid hypermelanosis?
Developmental and growth retardation; facial and body asymmetry; ventricular septal defects; pseudohermaphroditism.
What histopathological findings are associated with congenital linear and whorled nevoid hypermelanosis?
Increased pigmentation of the basal layer; prominence or vacuolization of melanocytes; pigment incontinence is usually absent.
What is the typical clinical course and prognosis for congenital linear and whorled nevoid hypermelanosis?
Typical onset is within the first few weeks of life; hyperpigmentation may fade gradually with advancing age.
What are the common ocular and CNS manifestations in patients with Incontinentia Pigmenti?
Ocular manifestations occur in 30-70% of patients; CNS manifestations occur in 40% of patients.
What is the significance of the IKBKG gene in the pathogenesis of Incontinentia Pigmenti?
The IKBKG gene encodes a regulatory component of the IKappaB kinase complex, which is essential for activating the NF-kB pathway, protecting against apoptosis.
What are the differential diagnoses for congenital linear and whorled nevoid hypermelanosis?
Incontinentia pigmenti; epidermal nevus.
What management strategies are recommended for Incontinentia Pigmenti?
Topical steroids and topical tacrolimus in the vesicular stage; noncultured epidermal cell grafting for hypopigmented and atrophic scarring.
A newborn presents with widespread streaky hyperpigmented macules along the lines of Blaschko. What is the most likely diagnosis, and what are the associated extracutaneous manifestations?
The most likely diagnosis is Linear and Whorled Nevoid Hypermelanosis. Associated extracutaneous manifestations include developmental and growth retardation, facial and body asymmetry, ventricular septal defects, and pseudohermaphroditism.
A female infant develops vesicular lesions along the lines of Blaschko shortly after birth. Over time, these lesions progress to wart-like plaques and then hyperpigmented streaks. What is the diagnosis, and what gene mutation is responsible?
The diagnosis is Incontinentia Pigmenti (Bloch-Sulzberger Syndrome). It is caused by a mutation in the IKBKG gene (previously NEMO).
What are the key clinical features of Dyskeratosis Congenita (Zinsser-Cole-Engman syndrome)?
Reticulate skin pigmentation: especially on the neck and chest; nail atrophy: in fingernails and toenails; leukoplakia; extraneous manifestations: bone marrow failure (more than 80% of cases) and malignancy.
What is the etiology of Dyskeratosis Congenita?
Caused by mutations in components of the telomerase complex; X-linked DKC: mutations in DKC1 gene at Xq28 encoding dyskerin; autosomal dominant DKC: primarily caused by mutations in TERC; autosomal recessive form: involves mutations in telomerase-associated proteins such as NOP10, NHP2, and TINF2.
What are the clinical features of Naegeli-Franceschetti-Jadassohn syndrome?
Reticulate hyperpigmentation: most prominent in neck and axillae; palmoplantar diffuse keratoderma; absence of dermatoglyphs; nail and teeth changes; heat intolerance due to diminished or absent sweating.
What is the genetic basis of Naegeli-Franceschetti-Jadassohn syndrome?
Caused by mutations in the KRT14 gene, which encodes for keratin 14; mutations lead to fragility of basal keratinocytes and affect the development of dermatoglyphs and sweat glands.
How does Dermatopathia Pigmentosa Reticularis differ from Naegeli-Franceschetti-Jadassohn syndrome?
Dermatopathia pigmentosa reticularis is characterized by lifelong persistence of skin hyperpigmentation, partial alopecia, and absence of dental anomalies, while Naegeli-Franceschetti-Jadassohn syndrome does not have these features.
What are the histological findings in Dyskeratosis Congenita?
Epidermal atrophy and chronic inflammatory cell infiltrate with numerous melanophages in the upper dermis are usually observed, but specific changes are not demonstrated.
What are the clinical features of Dermatopathia Pigmentosa Reticularis?
Reticulate hyperpigmentation on the trunk; palmoplantar keratoderma with punctiform accentuation; nail and ocular changes; noncicatricial alopecia; ichthyosis; hypohidrosis; widespread hyperkeratotic lesions; ainhum formation; mechanic blister formation; pigmentation of the oral mucosa.
What is the prognosis for patients with autosomal dominant Dyskeratosis Congenita?
Patients with autosomal dominant form have a better prognosis than those with other forms, possibly due to the presence of an unaffected allele with some preservation of telomerase activity.
What are the histological features of Naegeli-Franceschetti-Jadassohn syndrome?
Numerous melanophages in the upper dermis, next to a patchy epidermal hyperpigmentation; eccrine glands appear normal in number and structure.
What are the differential diagnoses for Dyskeratosis Congenita?
Fanconi syndrome: characterized by short stature, hypoplastic or aplastic thumbs, and reduced number of carpal bones, with patchy hyperpigmentation appearing earlier than in Dyskeratosis Congenita.
A patient presents with reticulate hyperpigmentation on the neck and chest, nail atrophy, and leukoplakia. What is the underlying genetic defect, and what are the associated risks?
The condition is Dyskeratosis Congenita, caused by mutations in components of the telomerase complex. Associated risks include bone marrow failure and malignancies.
A child presents with reticulate hyperpigmentation on the neck and axillae, absence of dermatoglyphs, and heat intolerance. What is the diagnosis, and what gene mutation is implicated?
The diagnosis is Naegeli-Franceschetti-Jadassohn Syndrome, caused by mutations in the KRT14 gene.