115 Questions
What are the four classic clinical features of lichen planus?
Purple, polygonal, pruritic, papules
What type of immunity plays a major role in the pathogenesis of lichen planus?
Cell-mediated immunity
What does the term 'lichen planus' mean in Greek and Latin?
'Tree moss'; 'flat'
What cytokine plays a central role in lichen planus?
Interferon- (IFN-)
Which receptor is predominantly expressed on the surface of IFN-–producing CD4-Th cells?
CXCL-9
Which cells are likely the terminal effector cells in lichen planus?
CD8-Tc cells
Which cytokine upregulates the expression of matrix metalloproteinase-9 (MMP-9) in lesional T lymphocytes of oral lichen planus?
Tumor necrosis factor- (TNF-)
What is correlated with high levels of ulcerative disease in lichen planus?
Matrix metalloproteinase-9 (MMP-9)
What is the effector cell of lichen planus?
CD8-Tc cells
What do Langerhans cells upregulate in lichenoid disease?
MHC class II receptors
Which type of immunity is involved in the pathogenesis of lichen planus?
Cell-mediated immunity
What role do CD4-Th cells play after costimulation by Langerhans cells?
Release of inflammatory cytokines like IFN-γ
What do circulating antibodies indicate in lichen planus?
Clear target antigen
What might act as haptens and elicit an immunologic response in lichen planus?
Inorganic mercury
What has been found in patients with oral lichenoid tissue reactions?
Enhanced lymphocyte reactivity to inorganic mercury
What has been implicated in dysregulated cytokine production and the development of lichenoid tissue reactions?
Type I IFN and TNF-α inhibitors
What has elicited recurring debate regarding its role in the development of lichen planus?
Microbial mediators
What has been identified as potentially stimulating a lymphocytic reaction leading to lichen planus?
Inorganic mercury exposure
What type of immunity is primarily involved in the pathogenesis of lichen planus?
Cell-mediated immunity
Which cells are consistently found in the dermis despite disease chronicity in lichen planus?
CD4+ cells
According to modern theories, what are the three major stages encompassing the pathogenesis of lichen planus?
Antigen recognition, lymphocyte activation, keratinocyte apoptosis
What is the role of humoral immunity in the pathogenesis of lichen planus?
Secondary response in immunopathogenesis
What is the role of CD8-Tc cells in lichen planus?
Initial antigen recognition and effector cell
Which cell type is reported to express a lichen planus–specific antigen associated with major histocompatibility complex (MHC) class I on keratinocytes?
CD4-Th cells
Where are the CD4-Th population localized in lichen planus?
Dermis with scattered cells in the epidermis
Which cells play a central role in antigen presentation and the initiation of the Th1 response in lichen planus?
Langerhans cells
What type of T cells release inflammatory cytokines upon costimulation by Langerhans cells in lichen planus?
CD4-Th cells
Which component of dental amalgam has been found to enhance lymphocyte reactivity in patients with oral lichen planus?
Mercury
What type of reaction may low-grade chronic exposure to mercury and other metals stimulate in lichen planus?
Lymphocytic reaction
What has been implicated in the dysregulated cytokine production leading to lichenoid tissue reactions?
Upregulation of type I IFN
What is the peak age range for the onset of lichen planus?
30-60 years
What percentage of lichen planus cases does childhood lichen planus account for in the general population?
1-5%
Is there a clear sexual or racial predilection in lichen planus?
No, it affects both sexes equally.
What are the characteristics of familial lichen planus?
Early onset, widespread, and frequent relapses
Which HLA haplotype is more common in patients with oral lichen planus alone?
HLA-B8
What is the characteristic color of the skin lesions in lichen planus?
Dull red-violet
Which feature of lichen planus is more easily visualized with dermoscopy?
Fine, white and adherent reticulate scale
Which area of the body is the most commonly involved in lichen planus?
Flexural wrists, arms, and legs
What is the typical morphology of the cutaneous lesions in lichen planus?
Flat-topped, polygonal papules
Which area is considered atypical for classic lichen planus?
Face and palms
What is the primary characteristic of lichen planus?
Severe pruritus
Which region is commonly involved in inverse lichen planus?
Axillae
What is the isomorphic phenomenon exhibited by lichen planus in the acute setting?
Koebner phenomenon
Which population has shown a predominance of childhood lichen planus in the United States?
African American children
What is the term used for the annular lesions found in approximately 10% of lichen planus cases?
Actinic lichen planus
What pattern may linear lichen planus follow?
Dermatomal lines
What is thought to be related to postzygotic, somatic mutations in susceptibility-associated genes in cases of Blaschkoid lichen planus?
Resident memory cells
(True/False) Zosteriform and linear lichen planus have been found to be the same disease.
False
(True/False) Hypopigmentation is common in lichen planus.
False
What is considered an atypical site for classic lichen planus?
Inguinal region
What cells are responsible for attacking fast dividing tissue in GVHD?
Cytotoxic CD8-positive T cells
What type of signaling drives chronic GVHD?
Th1/ Th17 signaling
What characteristic features are seen in lichenoid GVHD?
Classic lichenoid papules with prominent follicular involvement of the head and neck
Which cells are unable to develop GVHD in mice deficient of their receptors?
CD4-positive T-regulatory cells
What is the possible role of IL-17 blockade in lichen planus?
Transdifferentiation of Th17 cells into CD4-positive T-regulatory cells
What distinguishes lichenoid GVHD from lichen planus histopathologically?
Satellite cell necrosis, plasma cells, and monocytic infiltration
What is the most common site of involvement of oral lichen planus?
Buccal mucosa
Which form of oral lichen planus is often asymptomatic?
Reticular
What is the distinguishing feature of erosive and ulcerative oral lichen planus?
Extreme pain
What is the most common cause of desquamative gingivitis?
Oral lichen planus
What distinguishes oral lichenoid reactions (OLRs) from oral lichen planus?
Site of occurrence
What has been identified as a unique lichenoid eruption in individuals with HIV?
Tongue eruption
Which gender is most commonly affected in cases of esophageal lichen planus?
Middle-aged women
What type of lesions are commonly present in cases of anal mucosal lichen planus?
Leukokeratosis
What is the most common presentation of vulvar and vaginal lichen planus?
Symptomatic patches
Which area is commonly involved in inverse lichen planus?
Flexural areas like axillae and groin
What is the characteristic color of the skin lesions in palmoplantar lichen planus?
Red-brown
In which population has inverse lichen planus been most commonly reported?
Asians
What are the differential diagnoses for isolated nail lichen planus?
Psoriasis, alopecia areata, and atopic dermatitis
What is a characteristic feature of palmoplantar lichen planus lesions on the hands?
Callus-like appearance with purple hue
What is the term preferred by some to describe inverse lichen planus?
Lichen pigmentosus inversus
What is the most common age group affected by the latter two forms of nail lichen planus?
Adolescents and young adults
What percentage of individuals with palmoplantar lichen planus have other areas of cutaneous involvement?
~25%
What distinguishes palmoplantar lichen planus from other types of lichen planus?
$100% have Wickham striae
Which pattern is rare and characterized by red-brown, discrete papules and flat-topped plaques?
Inverse lichen planus
What color are the yellow, compact keratotic papules or papulonodules seen on the lateral margins of the fingers and hand surfaces in palmoplantar lichen planus?
Yellowish-brown
Which area may be rarely involved in inverse lichen planus?
Antecubital and popliteal areas
What is the most common cause of oral lichenoid eruptions?
Dental restorations metals
Which dermatosis has distinct clinical and histologic features and is characterized by lichenoid, keratotic papules and plaques in a seborrheic distribution with characteristic linear or reticulate pattern?
Keratosis Lichenoides Chronica
Which variant of lichen planus is characterized by features of lichen planus and lupus erythematosus?
Lichen Planus–Lupus Erythematosus Overlap
What is the characteristic color of the lesions in lichen planus pemphigoides?
Red-violet
What is the major consideration in the differential diagnosis of lichen planus pemphigoides?
Bullous lichen planus
What antigen may be unique for lichen planus pemphigoides?
BPAG180
What is the characteristic distribution pattern of keratosis lichenoides chronica?
Seborrheic distribution with a linear or reticulate pattern
What is the characteristic color of the skin lesions in lichen planus–lupus erythematosus overlap?
Red-violet
What type of immunity has been implicated in the pathogenesis of lichenoid graft versus host disease?
Cell-mediated immunity
Where do hypertrophic lichen planus lesions occur most commonly?
Anterior shins and interphalangeal joints
Which variant of lichen planus is characterized by oligo-lesional disease with well-marginated, blue-white papules or plaques with central atrophy?
Atrophic lichen planus
Where are vesiculobullous lesions in lichen planus more common?
Lower extremities
Which area is erosive and ulcerative cutaneous disease more common in lichen planus?
Feet
What is the characteristic color of the skin lesions in lichen planus pigmentosus?
Dark-brown
What is the primary characteristic of vesiculobullous lichen planus?
Development of vesicles and bullae
Where is follicular lichen planus most commonly found?
Scalp
Which type of lichen planus is associated with chronic lesions of ulcerative oral lichen planus leading to squamous cell carcinoma?
Atrophic lichen planus
Where are the lesions of hypertrophic lichen planus most commonly found?
Anterior shins and interphalangeal joints
What is a common clinical entity in the differential diagnosis of atrophic lichen planus?
Mycosis fungoides (MF)
Which morphological feature is characteristic of atrophic lichen planus?
Blue-white papules or plaques with central atrophy
Where is vesiculobullous disease often symptomatic in lichen planus?
Oral cavity
Which subtype of lichen planus is characterized by cicatricial alopecia of the scalp, nonscarring alopecia of the axilla and groin, and follicular papules on the trunk and extremities?
GLPLS
Which variant of lichen planus on the scalp consists of diffuse erythema with perifollicular hyperkeratosis and livid erythema?
Lichen planopilaris
Which area of the body is most commonly affected by actinic lichen planus?
Face
What is the primary color of the annular well-marginated, hyperpigmented brown-violet, flat-topped plaques associated with actinic lichen planus?
Brown-violet
Which condition was once considered uncommon but has seen a dramatic increase in recent years, especially in postmenopausal women?
Frontal fibrosing alopecia
Which dermoscopic feature aids in the diagnosis of early scarring lichen planopilaris?
Cicatricial white patches
What has been identified as potentially stimulating a lymphocytic reaction leading to lichen planus?
Low-grade chronic exposure to mercury
What is the long-term sequelae associated with vulvovaginal gingival syndrome?
Fibrosis and stricture
What has been found in 80% of individuals with vulvovaginal gingival syndrome?
Class II HLA DBQ1–0201 allele
What should be considered in the differential diagnosis if a patient presents with severe oral and ocular disease and a lichenoid infiltrate on biopsy?
Paraneoplastic autoimmune multiorgan syndrome
What is an irreversible process in nail lichen planus involving the matrix?
Dorsal pterygium
Which form of nail lichen planus is characterized by diffuse nail involvement with thinning, longitudinal ridging, and distal nail splitting?
Classic nail lichen planus
What is the characteristic feature of idiopathic atrophy of the nails?
Abrupt onset and rapidly progressive thinning of the nails
Which condition may present as cicatricial conjunctivitis?
Conjunctival lichen planus
What is another rare manifestation of lichen planus affecting the external auditory canal and the tympanic membrane?
Otic lichen planus
What does dermoscopy aid in the early diagnosis of?
Nail lichen planus
What are the major forms of nail lichen planus?
Classic nail lichen planus, 20-nail dystrophy, and idiopathic atrophy of the nails.
Explore the lack of conclusive evidence linking lichen planus to various infections or colonization, and delve into the activation of CD8-Tc cells and their oligoclonal expansion following antigen recognition.
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