33: Lichen Nitidus and Lichen Striatus Flashcards
What is the etiology of Lichen Nitidus?
Lichen Nitidus is associated with an idiopathic lichenoid tissue reaction involving exogenous antigens and allergens stimulating epidermal and dermal APCs (e.g., Langerhans cells), leading to a cell-mediated response and lymphocyte accumulation.
What are the clinical findings associated with Lichen Nitidus?
Clinical findings include multiple 1-2mm discrete smooth round skin-colored papules, which may be umbilicated with a glistening appearance. Scale can be elicited by rubbing the surface, and it is asymptomatic in most cases, with pruritus in 12%. Common sites include the trunk, genitalia, face, neck, hands, and lower extremities.
What is the prognosis for patients with Lichen Nitidus?
The prognosis is generally favorable, with resolution occurring spontaneously within 1 year in 2/3 of patients. Palmoplantar disease tends to have a more chronic course, but healing occurs without scar formation or pigmentary abnormalities.
What are the treatment options for Lichen Nitidus?
Treatment options include mid to high potency topical corticosteroids, tacrolimus for facial and intertriginous areas, PUVA, NBUVB, oral antihistamines for pruritus, and short course low dose oral glucocorticoids (e.g., prednisone 0.3mg/kg) for extensive or symptomatic disease.
What are the pathological features of Lichen Nitidus?
Pathological features include a dense infiltrate of lymphocytes, histiocytes, and Touton-type giant cells, elongation of rete ridges, thinning of the overlying epidermis in 90% of cases, and central parakeratosis without hypergranulosis.
What are the clinical features of actinic Lichen Nitidus?
Actinic Lichen Nitidus occurs in dark-skinned individuals and is characterized by lesions in areas of sun exposure.
What are the clinical features of spinous-follicular Lichen Nitidus?
Spinous-follicular Lichen Nitidus is a rare morphologic variant characterized by follicular involvement.
What is the role of low-dose oral glucocorticoids in Lichen Nitidus?
Low-dose oral glucocorticoids (e.g., prednisone 0.3 mg/kg) may be used to hasten resolution of extensive, generalized, or symptomatic Lichen Nitidus.
What is the clinical presentation of vesicular Lichen Nitidus?
Vesicular Lichen Nitidus is a rare morphologic variant characterized by vesicle formation.
What is the clinical significance of pruritus in Lichen Nitidus and Lichen Striatus?
Pruritus is present in 12% of Lichen Nitidus cases and 5-34% of Lichen Striatus cases, being more common in atopic individuals and adults.
What are the histological features of capillary wall degeneration in Lichen Nitidus?
Capillary wall degeneration is associated with purpuric or hemorrhagic lesions and RBC extravasation.
What is the significance of Touton-type giant cells in Lichen Nitidus?
Touton-type giant cells are part of the dense infiltrate, contributing to the ‘ball’ in the ‘ball and claw’ histological pattern.
What is the role of PUVA and NBUVB in Lichen Nitidus?
PUVA and NBUVB phototherapy are used for generalized patterns or lesions in cosmetic areas.
What is the role of macrophages in the pathogenesis of Lichen Nitidus and Lichen Striatus?
Macrophages (CD14+, CD68+) are part of the infiltrate in Lichen Nitidus, while dermal macrophages are common in Lichen Striatus, contributing to the immune response.
What is the clinical presentation of keratoderma in Lichen Nitidus?
Keratoderma presents as minute keratotic spicules or central plugs on the central palmar surface.
A patient presents with multiple 1-2mm smooth, round, skin-colored papules on the trunk and hands. What is the likely diagnosis, and what is the underlying pathophysiology?
The likely diagnosis is Lichen Nitidus, with pathophysiology involving exogenous antigens stimulating epidermal and dermal APCs, activating a cell-mediated response and lymphocyte accumulation.
What histological pattern is described as a ‘ball and claw’ in Lichen Nitidus?
The ‘ball and claw’ pattern refers to a dense infiltrate (‘ball’) of lymphocytes, histiocytes, and Touton-type giant cells embraced by elongated rete ridges (‘claw’).
A patient with Lichen Nitidus has pinpoint papules on the central palmar surface. What are the associated histological findings?
Palmar lesions show deep parakeratotic plugs.
What is the first-line treatment for Lichen Nitidus, and when is tacrolimus preferred?
First-line treatment includes mid to high potency topical corticosteroids. Tacrolimus is preferred for facial and intertriginous areas.
How does the immune cell profile differ between Lichen Nitidus and Lichen Striatus?
In Lichen Nitidus, the majority of infiltrating cells are T lymphocytes (CD4+ > CD8+). In Lichen Striatus, CD8+ cells predominate at the dermoepidermal junction.
What is the prognosis for Lichen Nitidus and Lichen Striatus?
Lichen Nitidus resolves spontaneously within one year in two-thirds of patients, while Lichen Striatus is self-limited with a mean duration of 6-12 months.
What are the rare morphologic variants of Lichen Nitidus, and where are they commonly found?
Rare morphologic variants include vesicular, hemorrhagic-purpuric, spinous-follicular, and actinic Lichen Nitidus.
What is the significance of the Koebner phenomenon in Lichen Nitidus?
The Koebner phenomenon, seen in 12% of cases, refers to the appearance of lesions at sites of trauma.
What is the role of phototherapy in the treatment of Lichen Nitidus?
Phototherapy options include PUVA and NBUVB for generalized patterns or lesions in cosmetic areas.
What are the clinical features of hemorrhagic-purpuric lesions in Lichen Nitidus?
Hemorrhagic-purpuric lesions are associated with capillary wall degeneration and RBC extravasation.
What is the significance of colloid bodies in Lichen Nitidus and Lichen Striatus?
Colloid bodies are seen in 10% of Lichen Nitidus cases and represent degenerated keratinocytes.
What are the histological features of perforating lesions in Lichen Nitidus?
Perforating lesions occur in areas of friction and are characterized by deep parakeratotic plugs.
What is the primary mechanism by which exogenous antigens lead to the formation of inflammatory papules in Lichen Nitidus?
Exogenous antigens stimulate epidermal and dermal APCs, activating a cell-mediated response that initiates lymphocyte accumulation.
What are the most common clinical findings associated with Lichen Nitidus?
Common findings include multiple 1-2mm discrete smooth round skin-colored papules, scale elicited by rubbing, and pruritus in 12% of cases.
Describe the histopathological features observed in Lichen Nitidus.
Histopathological features include a dense infiltrate of lymphocytes, histiocytes, and Touton-type giant cells, elongation of dermal ridges, and central parakeratosis.
What is the prognosis for patients with Lichen Nitidus, and how does it typically resolve?
Lichen Nitidus typically resolves spontaneously within 1 year in 2/3 of patients, with healing occurring without scar formation.
What are the first-line treatment options for Lichen Nitidus, particularly for symptomatic cases?
First-line options include mid to high potency topical corticosteroids and tacrolimus for facial and intertriginous areas.
What are the key differences in incidence and lesion characteristics between Lichen Nitidus and Lichen Planus?
Feature | Lichen Nitidus | Lichen Planus |
|—————|—————-|—————-|
| Incidence | Rare | Common |
| Lesion Size | Usually 1-2 mm | Variable, usually larger |
| Shape | Round | Polygonal |
| Color | Flesh, pink, red-brown | Erythematous to violaceous |
| Wickham Striae| Absent | Present |
What are the differential diagnoses for Lichen Nitidus?
Condition | Characteristics |
|————————-|—————–|
| Lichen Planus | Larger polymorphic lesions located on flexural wrist, arms, and legs; highly pruritic; CD8 lymphocytes predominate. |
| Psoriasis | Plaques have silvery scale. |
| Verruca plana | Limited, asymmetric involvement; verrucous surface. |
| Keratosis pilaris | Commonly seen on the cheeks, lateral arms, and lateral hips. |
| Persistent disease | Shows periorbital scaling with keratotic plug formation.
What are the second-line treatment options for Lichen Nitidus?
Second-line options include topical tacrolimus, UVA and UVB therapy, and local PUVA for palmar lesions.
What systemic treatments can be considered for Lichen Nitidus?
Systemic treatments may include oral steroids, oral retinoids (acitretin), low-dose cyclosporine, itraconazole, antituberculous agents, and enoxaparin.
What is the typical duration of lichen striatus and its prognosis?
Lichen striatus is self-limited with a mean duration of approximately 6 to 12 months, and the prognosis is good.
What are the classic pathologic findings associated with lichen striatus?
Classic findings include hyperkeratosis, focal parakeratosis, mild spongiosis, keratinocyte necrosis, and perivascular lymphocytic infiltrate.
What is the prognosis for Lichen Striatus?
The prognosis for Lichen Striatus is generally good. It is a self-limited disease with a mean duration of approximately 6 to 12 months, and relapse is rare.
What are the classic pathologic findings associated with Lichen Striatus?
Classic pathologic findings include:
- Hyperkeratosis and focal parakeratosis.
- Mild spongiosis with lichenoid tissue reaction and exocytosis.
- Keratinocyte necrosis and perivascular and appendageal lymphocytic infiltrate.
- Superficial lichenoid dermatitis and deep lymphocytic infiltrate are present in almost all cases.
What are the common areas of predilection for Lichen Striatus?
The common areas of predilection for Lichen Striatus are:
- Extremities (75% to 77%)
- Trunk (9% to 21%)
- Face (3% to 13%)
- Nails (2.6%)
What external factors have been implicated in triggering Lichen Striatus?
External precipitants implicated in triggering Lichen Striatus include:
- Environmental stressors
- Drugs (e.g., interferon)
- Vaccines (e.g., BCG)
- Viral antigens
- Hypersensitivity
- Skin injury
What is the role of topical calcineurin inhibitors in the treatment of Lichen Striatus?
Topical calcineurin inhibitors, such as pimecrolimus, are used for facial involvement or disease refractory to topical corticosteroids in Lichen Striatus. Significant improvement is often seen within six weeks.
What is the clinical significance of seasonal variation in Lichen Striatus?
Seasonal variation, with outbreaks in spring and summer, supports an infectious etiology for Lichen Striatus.
What is the significance of decreased Langerhans cells in Lichen Striatus?
Decreased Langerhans cells in Lichen Striatus suggest a localized immune dysregulation, although intraepidermal vesicles may contain Langerhans cells along with T lymphocytes in 23-45% of cases.
What is the significance of postinflammatory hypopigmentation in Lichen Striatus?
Postinflammatory hypopigmentation is seen in 50% of Lichen Striatus cases but is self-limited and resolves without scarring.
What are the histological features of superficial lichenoid dermatitis in Lichen Striatus?
Superficial lichenoid dermatitis in Lichen Striatus is characterized by a lichenoid tissue reaction with lymphocytic infiltrate.
What is the role of intralesional corticosteroids in Lichen Striatus with nail involvement?
Intralesional corticosteroids (e.g., triamcinolone 5 mg/mL) combined with topical corticosteroids and calcineurin inhibitors have shown improvement in nail involvement in Lichen Striatus.
What is the clinical presentation of Blaschko-linear acquired inflammatory skin eruption (BLAISE)?
BLAISE, another term for Lichen Striatus, presents as a sudden onset of flat-topped, 1-3mm pink, tan, or hypopigmented papules in a linear configuration along Blaschko lines.
What is the clinical significance of mild spongiosis in Lichen Striatus?
Mild spongiosis in Lichen Striatus is a histological feature indicating epidermal inflammation.
What is the significance of somatic mosaicism in Lichen Striatus?
Somatic mosaicism in Lichen Striatus involves postzygotic somatic mutations in keratinocytes, leading to altered antigens that migrate along Blaschko lines and trigger an immune response.
A patient presents with a linear configuration of 1-3mm pink papules on the extremities. What is the likely diagnosis, and what is the proposed etiology?
The likely diagnosis is Lichen Striatus. The proposed etiology involves somatic mosaicism, where postzygotic somatic mutations in keratinocytes lead to altered antigens that migrate along Blaschko lines, triggering an immune response.
What are the common histological findings in Lichen Striatus?
Histological findings in Lichen Striatus include hyperkeratosis, focal parakeratosis, mild spongiosis, lichenoid tissue reaction, exocytosis, keratinocyte necrosis, and perivascular and appendageal lymphocytic infiltrate.
A patient with Lichen Striatus has nail involvement. What are the clinical features and treatment options?
Nail involvement in Lichen Striatus may include longitudinal ridging, onycholysis, splitting, fraying, and loss of the nail plate. Treatment options include topical corticosteroids, calcineurin inhibitors, and intralesional corticosteroids (e.g., triamcinolone).
What is the role of environmental stressors in the pathogenesis of Lichen Striatus?
Environmental stressors, such as drugs (e.g., interferon), vaccines (e.g., BCG), viral antigens, hypersensitivity, and skin injury, are implicated in the loss of immune tolerance and triggering an immune response in Lichen Striatus.
What are the histological mimickers of Lichen Striatus?
Histological mimickers of Lichen Striatus include lichen planus, lupus erythematosus, graft-versus-host disease (GVHD), lichen planopilaris, mycosis fungoides, syphilis, and atypical dermatitis.
What is the role of oral antihistamines in managing Lichen Striatus?
Oral antihistamines may be helpful in managing generalized itch or sleep disruption in Lichen Striatus.
What is the typical distribution of Lichen Striatus lesions?
Lichen Striatus lesions are typically distributed along Blaschko lines, with predilection for the extremities (75-77%), trunk (9-21%), face (3-13%), and nails (2.6%).
What is the significance of the Blaschko-linear pattern in the etiology of Lichen Striatus?
The Blaschko-linear pattern suggests somatic mosaicism, indicating that postzygotic somatic mutations of keratinocytes lead to the development of altered antigens that migrate along the lines of Blaschko, triggering an immune response.
What are the common clinical features of Lichen Striatus?
Lichen Striatus is characterized by:
1. Sudden onset of flat-topped, 1-3 mm, pink, tan, or hypopigmented papules.
2. Linear configuration or Blaschkoid distribution.
3. Pruritus occurs in 5% to 34% of cases.
4. Predilection areas include extremities, trunk, face, and nails.
What are the first-line treatment options for managing Lichen Striatus?
First-line treatment options include:
1. Topical steroids of low to medium potency for symptomatic control of pruritus.
2. Topical calcineurin inhibitors and Pimecrolimus for refractory cases.
3. For nail involvement, topical corticosteroids combined with calcineurin inhibitors and intralesional corticosteroids have shown improvement.
What are the characteristics of Linear Lichen Planus in the differential diagnosis of Lichen Striatus?
Linear Lichen Planus is characterized by older patients, violaceous primary lesions, high pruritus, brisk lichenoid tissue reaction, and positive DIF.
What are the key features of Inflammatory Linear Verrucous Epidermal Nevus?
Inflammatory Linear Verrucous Epidermal Nevus occurs in children, appears psoriasis-like, is highly pruritic, and most resolve by adulthood.
What are the characteristics of Blaschkitis in the differential diagnosis of Lichen Striatus?
Blaschkitis is characterized by older patients, truncal papular eruption with multiple streaks, features of concomitant dermatitis, and often resolves in days to weeks.
What conditions should be considered in the differential diagnosis of Lichen Striatus?
Conditions to consider include Linear psoriasis, Linear Darier disease, Linear porokeratosis, Linear lichen nitidus, and Incontinentia pigmenti.
Most frequent sites of LN?
trunk, genitalia, face, neck, hands, and lower extremities
Palmoplantar involvement in LN are more common in what demographic?
adults
Hemorrhagic / purpuric LN is common in what sites?
palms and distal extremities
LN is more common in which demographic?
children and young adults
Rare disease associations of LN?
AD
Crohn disease
Juvenile chronic arthritis
LN is seen in histopathology as embracement by neighboring rete ridges around a focused dense infiltrate ball of lymphocytes, histiocytes and touton type giant cells, with the involvemenet of _____ dermal papillae.
less than or equal to 3
DIF finding of LN?
Negative
Differentiate LN and LP clinically and histopathologically.
LN is typically a focal, asymptomatic, chronic inflammatory reaction that eventually resolves spontaneously within _____ in 2/3 of patients or, less
frequently, over a few years. _____ disease may be associated with a more chronic course.
1 year
palmoplantar
Do lesions in LN heal with scars and pigmentary abnormalities?
No.
1st, 2nd and 3rd line treatment for LN?
Demographic most commonly affected in LS?
<18 years (mean age of onset: 3 - 5 years of age)
Pruritis (5-34% of cases) in LS is more common in _____ and _____.
Atopic
Adults
Most common locations involved in LS?
extremities and trunk > face and nails
Nail findings in LS?
longitudinal ridging
onycholysis
splitting
fraying
loss of the nail plate (reversible with treatment)
Possible precipitating factors of LS?
environmental stressors
drugs (specifically interferon)
vaccines (bacillus Calmette–Guérin)
viral antigens
hypersensitivity
skin injury
LS is prevalent in what seasons?
Spring
Summer
Histopathologic features of LS seen in almost all cases?
superficial lichenoid dermatitis
deep lymphocytic infiltrate
LS is a self limited disease (approximately _____). Post-inflammatory hypopigmentation is found in _____% of cases. Lesions heal _____ scarring.
6 to 12 months
50%
without
1st line for pruritus in LS?
Topical steroids (low to midpotent)
Topical tacrolimus / pimecrolimus for facial involvement or refractory LS is used up to _____.
6 weeks
Treatment for nail LS?
Topical steroid + topical C.I. + intralesional triamcinolone (5mg/ml)
Most likely DDx of LS and how to differentiate?
Linear LP
ILVEN
Blaschkitis
LN exhibits koebner reaction in ___% of cases.
12%
