33: Lichen Nitidus and Lichen Striatus

Question 1

What is the etiology of Lichen Nitidus?

Answer 1

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.

Question 2

What are the clinical findings associated with Lichen Nitidus?

Answer 2

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.

Question 3

What is the prognosis for patients with Lichen Nitidus?

Answer 3

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.

Question 4

What are the treatment options for Lichen Nitidus?

Answer 4

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.

Question 5

What are the pathological features of Lichen Nitidus?

Answer 5

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.

Question 6

What are the clinical features of actinic Lichen Nitidus?

Answer 6

Actinic Lichen Nitidus occurs in dark-skinned individuals and is characterized by lesions in areas of sun exposure.

Question 7

What are the clinical features of spinous-follicular Lichen Nitidus?

Answer 7

Spinous-follicular Lichen Nitidus is a rare morphologic variant characterized by follicular involvement.

Question 8

What is the role of low-dose oral glucocorticoids in Lichen Nitidus?

Answer 8

Low-dose oral glucocorticoids (e.g., prednisone 0.3 mg/kg) may be used to hasten resolution of extensive, generalized, or symptomatic Lichen Nitidus.

Question 9

What is the clinical presentation of vesicular Lichen Nitidus?

Answer 9

Vesicular Lichen Nitidus is a rare morphologic variant characterized by vesicle formation.

Question 10

What is the clinical significance of pruritus in Lichen Nitidus and Lichen Striatus?

Answer 10

Pruritus is present in 12% of Lichen Nitidus cases and 5-34% of Lichen Striatus cases, being more common in atopic individuals and adults.

Question 11

What are the histological features of capillary wall degeneration in Lichen Nitidus?

Answer 11

Capillary wall degeneration is associated with purpuric or hemorrhagic lesions and RBC extravasation.

Question 12

What is the significance of Touton-type giant cells in Lichen Nitidus?

Answer 12

Touton-type giant cells are part of the dense infiltrate, contributing to the ‘ball’ in the ‘ball and claw’ histological pattern.

Question 13

What is the role of PUVA and NBUVB in Lichen Nitidus?

Answer 13

PUVA and NBUVB phototherapy are used for generalized patterns or lesions in cosmetic areas.

Question 14

What is the role of macrophages in the pathogenesis of Lichen Nitidus and Lichen Striatus?

Answer 14

Macrophages (CD14+, CD68+) are part of the infiltrate in Lichen Nitidus, while dermal macrophages are common in Lichen Striatus, contributing to the immune response.

Question 15

What is the clinical presentation of keratoderma in Lichen Nitidus?

Answer 15

Keratoderma presents as minute keratotic spicules or central plugs on the central palmar surface.

Question 16

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?

Answer 16

The likely diagnosis is Lichen Nitidus, with pathophysiology involving exogenous antigens stimulating epidermal and dermal APCs, activating a cell-mediated response and lymphocyte accumulation.

Question 17

What histological pattern is described as a ‘ball and claw’ in Lichen Nitidus?

Answer 17

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’).

Question 18

A patient with Lichen Nitidus has pinpoint papules on the central palmar surface. What are the associated histological findings?

Answer 18

Palmar lesions show deep parakeratotic plugs.

Question 19

What is the first-line treatment for Lichen Nitidus, and when is tacrolimus preferred?

Answer 19

First-line treatment includes mid to high potency topical corticosteroids. Tacrolimus is preferred for facial and intertriginous areas.

Question 20

How does the immune cell profile differ between Lichen Nitidus and Lichen Striatus?

Answer 20

In Lichen Nitidus, the majority of infiltrating cells are T lymphocytes (CD4+ > CD8+). In Lichen Striatus, CD8+ cells predominate at the dermoepidermal junction.

Question 21

What is the prognosis for Lichen Nitidus and Lichen Striatus?

Answer 21

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.

Question 22

What are the rare morphologic variants of Lichen Nitidus, and where are they commonly found?

Answer 22

Rare morphologic variants include vesicular, hemorrhagic-purpuric, spinous-follicular, and actinic Lichen Nitidus.

Question 23

What is the significance of the Koebner phenomenon in Lichen Nitidus?

Answer 23

The Koebner phenomenon, seen in 12% of cases, refers to the appearance of lesions at sites of trauma.

Question 24

What is the role of phototherapy in the treatment of Lichen Nitidus?

Answer 24

Phototherapy options include PUVA and NBUVB for generalized patterns or lesions in cosmetic areas.

Question 25

What are the clinical features of hemorrhagic-purpuric lesions in Lichen Nitidus?

Answer 25

Hemorrhagic-purpuric lesions are associated with capillary wall degeneration and RBC extravasation.

Question 26

What is the significance of colloid bodies in Lichen Nitidus and Lichen Striatus?

Answer 26

Colloid bodies are seen in 10% of Lichen Nitidus cases and represent degenerated keratinocytes.

Question 27

What are the histological features of perforating lesions in Lichen Nitidus?

Answer 27

Perforating lesions occur in areas of friction and are characterized by deep parakeratotic plugs.

Question 28

What is the primary mechanism by which exogenous antigens lead to the formation of inflammatory papules in Lichen Nitidus?

Answer 28

Exogenous antigens stimulate epidermal and dermal APCs, activating a cell-mediated response that initiates lymphocyte accumulation.

Question 29

What are the most common clinical findings associated with Lichen Nitidus?

Answer 29

Common findings include multiple 1-2mm discrete smooth round skin-colored papules, scale elicited by rubbing, and pruritus in 12% of cases.

Question 30

Describe the histopathological features observed in Lichen Nitidus.

Answer 30

Histopathological features include a dense infiltrate of lymphocytes, histiocytes, and Touton-type giant cells, elongation of dermal ridges, and central parakeratosis.

Question 31

What is the prognosis for patients with Lichen Nitidus, and how does it typically resolve?

Answer 31

Lichen Nitidus typically resolves spontaneously within 1 year in 2/3 of patients, with healing occurring without scar formation.

Question 32

What are the first-line treatment options for Lichen Nitidus, particularly for symptomatic cases?

Answer 32

First-line options include mid to high potency topical corticosteroids and tacrolimus for facial and intertriginous areas.

Question 33

What are the key differences in incidence and lesion characteristics between Lichen Nitidus and Lichen Planus?

Answer 33

| 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 |

Question 34

What are the differential diagnoses for Lichen Nitidus?

Answer 34

| 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.

Question 35

What are the second-line treatment options for Lichen Nitidus?

Answer 35

Second-line options include topical tacrolimus, UVA and UVB therapy, and local PUVA for palmar lesions.

Question 36

What systemic treatments can be considered for Lichen Nitidus?

Answer 36

Systemic treatments may include oral steroids, oral retinoids (acitretin), low-dose cyclosporine, itraconazole, antituberculous agents, and enoxaparin.

Question 37

What is the typical duration of lichen striatus and its prognosis?

Answer 37

Lichen striatus is self-limited with a mean duration of approximately 6 to 12 months, and the prognosis is good.

Question 38

What are the classic pathologic findings associated with lichen striatus?

Answer 38

Classic findings include hyperkeratosis, focal parakeratosis, mild spongiosis, keratinocyte necrosis, and perivascular lymphocytic infiltrate.

Question 39

What is the prognosis for Lichen Striatus?

Answer 39

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.

Question 40

What are the classic pathologic findings associated with Lichen Striatus?

Answer 40

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.

Question 41

What are the common areas of predilection for Lichen Striatus?

Answer 41

The common areas of predilection for Lichen Striatus are: - Extremities (75% to 77%) - Trunk (9% to 21%) - Face (3% to 13%) - Nails (2.6%)

Question 42

What external factors have been implicated in triggering Lichen Striatus?

Answer 42

External precipitants implicated in triggering Lichen Striatus include: - Environmental stressors - Drugs (e.g., interferon) - Vaccines (e.g., BCG) - Viral antigens - Hypersensitivity - Skin injury

Question 43

What is the role of topical calcineurin inhibitors in the treatment of Lichen Striatus?

Answer 43

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.

Question 44

What is the clinical significance of seasonal variation in Lichen Striatus?

Answer 44

Seasonal variation, with outbreaks in spring and summer, supports an infectious etiology for Lichen Striatus.

Question 45

What is the significance of decreased Langerhans cells in Lichen Striatus?

Answer 45

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.

Question 46

What is the significance of postinflammatory hypopigmentation in Lichen Striatus?

Answer 46

Postinflammatory hypopigmentation is seen in 50% of Lichen Striatus cases but is self-limited and resolves without scarring.

Question 47

What are the histological features of superficial lichenoid dermatitis in Lichen Striatus?

Answer 47

Superficial lichenoid dermatitis in Lichen Striatus is characterized by a lichenoid tissue reaction with lymphocytic infiltrate.

Question 48

What is the role of intralesional corticosteroids in Lichen Striatus with nail involvement?

Answer 48

Intralesional corticosteroids (e.g., triamcinolone 5 mg/mL) combined with topical corticosteroids and calcineurin inhibitors have shown improvement in nail involvement in Lichen Striatus.

Question 49

What is the clinical presentation of Blaschko-linear acquired inflammatory skin eruption (BLAISE)?

Answer 49

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.

Question 50

What is the clinical significance of mild spongiosis in Lichen Striatus?

Answer 50

Mild spongiosis in Lichen Striatus is a histological feature indicating epidermal inflammation.

Question 51

What is the significance of somatic mosaicism in Lichen Striatus?

Answer 51

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.

Question 52

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?

Answer 52

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.

Question 53

What are the common histological findings in Lichen Striatus?

Answer 53

Histological findings in Lichen Striatus include hyperkeratosis, focal parakeratosis, mild spongiosis, lichenoid tissue reaction, exocytosis, keratinocyte necrosis, and perivascular and appendageal lymphocytic infiltrate.

Question 54

A patient with Lichen Striatus has nail involvement. What are the clinical features and treatment options?

Answer 54

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).

Question 55

What is the role of environmental stressors in the pathogenesis of Lichen Striatus?

Answer 55

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.

Question 56

What are the histological mimickers of Lichen Striatus?

Answer 56

Histological mimickers of Lichen Striatus include lichen planus, lupus erythematosus, graft-versus-host disease (GVHD), lichen planopilaris, mycosis fungoides, syphilis, and atypical dermatitis.

Question 57

What is the role of oral antihistamines in managing Lichen Striatus?

Answer 57

Oral antihistamines may be helpful in managing generalized itch or sleep disruption in Lichen Striatus.

Question 58

What is the typical distribution of Lichen Striatus lesions?

Answer 58

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%).

Question 59

What is the significance of the Blaschko-linear pattern in the etiology of Lichen Striatus?

Answer 59

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.

Question 60

What are the common clinical features of Lichen Striatus?

Answer 60

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.

Question 61

What are the first-line treatment options for managing Lichen Striatus?

Answer 61

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.

Question 62

What are the characteristics of Linear Lichen Planus in the differential diagnosis of Lichen Striatus?

Answer 62

Linear Lichen Planus is characterized by older patients, violaceous primary lesions, high pruritus, brisk lichenoid tissue reaction, and positive DIF.

Question 63

What are the key features of Inflammatory Linear Verrucous Epidermal Nevus?

Answer 63

Inflammatory Linear Verrucous Epidermal Nevus occurs in children, appears psoriasis-like, is highly pruritic, and most resolve by adulthood.

Question 64

What are the characteristics of Blaschkitis in the differential diagnosis of Lichen Striatus?

Answer 64

Blaschkitis is characterized by older patients, truncal papular eruption with multiple streaks, features of concomitant dermatitis, and often resolves in days to weeks.

Question 65

What conditions should be considered in the differential diagnosis of Lichen Striatus?

Answer 65

Conditions to consider include Linear psoriasis, Linear Darier disease, Linear porokeratosis, Linear lichen nitidus, and Incontinentia pigmenti.

Question 66

Most frequent sites of LN?

Answer 66

trunk, genitalia, face, neck, hands, and lower extremities

Question 67

Palmoplantar involvement in LN are more common in what demographic?

Answer 67

adults

Question 68

Hemorrhagic / purpuric LN is common in what sites?

Answer 68

palms and distal extremities

Question 69

LN is more common in which demographic?

Answer 69

children and young adults

Question 70

Rare disease associations of LN?

Answer 70

AD Crohn disease Juvenile chronic arthritis

Question 71

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.

Answer 71

less than or equal to 3

Question 72

DIF finding of LN?

Answer 72

Negative

Question 73

Differentiate LN and LP clinically and histopathologically.

Answer 73

Question 74

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.

Answer 74

1 year palmoplantar

Question 75

Do lesions in LN heal with scars and pigmentary abnormalities?

Answer 75

No.

Question 76

1st, 2nd and 3rd line treatment for LN?

Answer 76

Question 77

Demographic most commonly affected in LS?

Answer 77

<18 years (mean age of onset: 3 - 5 years of age)

Question 78

Pruritis (5-34% of cases) in LS is more common in _____ and _____.

Answer 78

Atopic Adults

Question 79

Most common locations involved in LS?

Answer 79

extremities and trunk > face and nails

Question 80

Nail findings in LS?

Answer 80

longitudinal ridging onycholysis splitting fraying loss of the nail plate (reversible with treatment)

Question 81

Possible precipitating factors of LS?

Answer 81

environmental stressors drugs (specifically interferon) vaccines (bacillus Calmette–Guérin) viral antigens hypersensitivity skin injury

Question 82

LS is prevalent in what seasons?

Answer 82

Spring Summer

Question 83

Histopathologic features of LS seen in almost all cases?

Answer 83

superficial lichenoid dermatitis deep lymphocytic infiltrate

Question 84

LS is a self limited disease (approximately _____). Post-inflammatory hypopigmentation is found in _____% of cases. Lesions heal _____ scarring.

Answer 84

6 to 12 months 50% without

Question 85

1st line for pruritus in LS?

Answer 85

Topical steroids (low to midpotent)

Question 86

Topical tacrolimus / pimecrolimus for facial involvement or refractory LS is used up to _____.

Answer 86

6 weeks

Question 87

Treatment for nail LS?

Answer 87

Topical steroid + topical C.I. + intralesional triamcinolone (5mg/ml)

Question 88

Most likely DDx of LS and how to differentiate?

Answer 88

Linear LP ILVEN Blaschkitis

Question 89

LN exhibits koebner reaction in ___% of cases.

Answer 89

12%