Lichen planus and lichenoid drug-induced eruption: a histological and immunohistochemical study

Hypertrophic Lichen Planus: An Up-to-Date Review and Differential Diagnosis

CONTEXT.—

Hypertrophic lichen planus (HLP) is a variant of lichen planus that can be difficult to diagnose based on histopathologic features alone. Thus, patient clinical history and clinicopathologic correlation are essential considerations to make the correct diagnosis.

OBJECTIVE.—

To discuss the clinical and histologic presentation of HLP and provide a thorough review of commonly encountered mimickers in the differential diagnosis.

DATA SOURCES.—

Data were derived from a literature review, personal clinical and research experiences, and a review of cases in the archives of a tertiary care referral center.

CONCLUSIONS.—

In general, HLP involves the lower extremities and is characterized by thickened, scaly nodules and plaques that are often pruritic and chronic in nature. HLP affects both males and females and is most common in adults 50 to 75 years of age. Unlike conventional lichen planus, HLP tends to have eosinophils and classically displays a lymphocytic infiltrate most concentrated around the tips of rete ridges. The differential diagnosis for HLP is broad and encompasses numerous entities in many different categories, including premalignant and malignant neoplasms, reactive squamoproliferative tumors, benign epidermal neoplasms, connective tissue disease, autoimmune bullous disease, infection, and drug-related reactions. Therefore, a high index of suspicion must be maintained to avoid a misdiagnosis and potential inappropriate treatments.

Clinical Profile of Patients with Lichenoid Drug Eruption: A Observational Study

Background

Lichenoid drug eruption (LDE) is an uncommon cutaneous adverse drug reaction, where a variety of drugs used in day-to-day clinical practice have been implicated.

Objective

To describe the clinico-demographic characteristics of patients with LDE and to identify the most likely drugs involved.

Methods

In this prospective, observational study, consecutive patients with LDE presenting to the dermatology department of a tertiary teaching hospital were included. The clinico-demographic profile of patients with LDE and implicated drugs was noted. Treatment of drug reaction along with outcome was also documented. Naranjo adverse drug reaction probability scale was used for causality assessment of the drug reactions. A thorough literature review on LDE was also undertaken due to the paucity of existing literature.

Results

A total of 15 patients (11 males and 4 females) with LDE were evaluated. Their age ranged from 37 to 61 years, with a mean of 51.53 ± 7.59 years. Anti-hypertensive medications (40%) were the most common culprit agent, followed by antitubercular drugs (33.4%), anti-diabetic agents (13.3%), and others (13.3%). The latent period (time from drug initiation to the appearance of a cutaneous eruption) varied from 15 days to 6 months (mean 2.2 months). Cutaneous involvement was generalized in 73.4% and photo-distributed lesions in 26.6%. Drug provocation test was done to identify the culprit drug. According to the Naranjo adverse drug reaction probability scale, one-third of LDEs were "definite," whereas two-thirds were designated as "probable."

Conclusion

LDE is more common in the elderly population. The latent period is comparatively longer in LDE than in other common drug reactions. Prompt recognition and withdrawal of suspected drug are essential to minimize disease morbidity.

Camrelizumab-induced oral lichenoid reaction with subepithelial CD4+ T-cell infiltration

INTRODUCTION

Camrelizumab is a novel anti-programed cell death-1 (PD-1) antibody that has been investigated for the treatment of various malignancies. Increasing immune-related adverse events have been reported in clinical practice, with CD4+ T-cell-mediated-reactive cutaneous capillary endothelial proliferation being the most common. Camrelizumab-induced oral lichenoid reaction (OLR) appears to be a rare adverse effect compared with other anti-PD therapies induced OLR, with the main pathogenesis of activated CD8+ T cells mediating autoimmune reactions. Herein, we report a rare case of camrelizumab-induced OLR and a possible pathogenic mechanism of subepithelial CD4+ T-cell infiltration.

CASE REPORT

A 57-year-old male patient, who was diagnosed with metastatic esophageal squamous cell carcinoma three years prior, presented with a two-month history of oral erosion that developed while under camrelizumab therapy. Diffuse erythematous and erosive lesions surrounded by bilateral white lesions on the buccal mucosa were detected in his physical examination. Hematoxylin and eosin staining of the lesions revealed the presence of basal keratinocyte degeneration and band-like subepithelial T-cell infiltration. The immunostaining for CD4 on T-cell was positive, while CD8 were sporadically positive. Flow cytometry showed a gradual increase in the CD4+ T-cell proportion in the peripheral blood, with the CD8+ T-cell percentage almost unchanged and in the normal range. We obtained a score of 6 based on the Naranjo algorithm, which means a probable adverse drug reaction.

MANAGEMENT AND OUTCOME

The patient exhibited notable improvement after two weeks of treatment with topical glucocorticoid without regulating his immunotherapy, and remained in stable condition in the follow-up.

DISCUSSION

This case may offer new insight to clinicians on the pathogenesis of anti-PD-1-induced OLR. More critically, it may provide some ideas for a more precise anti-PD therapy or corresponding combination therapy for patients becoming resistant to immunotherapy due to exhausted CD4+ T-cell responses in the tumor microenvironment.

The role of eosinophils in the differential diagnosis of inflammatory skin diseases

Eosinophils are known to be present in inflammatory skin diseases, but their diagnostic utility is not well established. Upon review of the published status of lesional eosinophils, several categories were identified. 1) Lesional eosinophils highly characteristic such that, in their absence, the pathologist may question the diagnosis. These include arthropod bite reactions and scabies, urticarial dermatitis, and other eosinophilic dermatoses. 2) Lesional eosinophils rare or absent, such that, in their presence, the pathologist may question the diagnosis. These include pityriasis lichenoides, graft versus host disease, and connective tissue disorders. 3) Lesional eosinophils variable and, while in some cases expected, are not required for diagnosis. These include drug reactions, atopic dermatitis and allergic contact dermatitis. 4) Lesional eosinophils variable and not expected but may be seen to a limited extent. These include lichen planus and psoriasis.

Molecular Mechanisms of Cutaneous Immune-Related Adverse Events (irAEs) Induced by Immune Checkpoint Inhibitors

Over the past few decades, immune checkpoint inhibitors (ICIs) have emerged as promising therapeutic options for the treatment of various cancers. These novel treatments effectively target key mediators of immune checkpoint pathways. Currently, ICIs primarily consist of monoclonal antibodies that specifically block cytotoxic T-lymphocyte antigen 4 (CTLA-4), programmed cell death 1 (PD-1), programmed cell death-ligand 1 (PD-L1), and lymphocyte activation gene 3 protein (LAG-3). Despite the notable efficacy of ICIs in cancer treatment, they can also trigger immune-related adverse events (irAEs), which present as autoimmune-like or inflammatory conditions. IrAEs have the potential to affect multiple organ systems, with cutaneous toxicities being the most commonly observed. Although cutaneous irAEs are typically of low-grade severity and can usually be managed effectively, there are cases where severe irAEs can become life-threatening. Therefore, early recognition and a comprehensive understanding of the mechanisms underlying cutaneous irAEs are crucial for improving clinical outcomes in cancer patients. However, the precise pathogenesis of cutaneous irAEs remains unclear. This review focuses on the skin manifestations induced by ICIs, the prognosis related to cutaneous irAEs, and the exploration of potential mechanisms involved in cutaneous irAEs.

A progressive pigmentary dermatosis

A 53-year-old Indian man presented with a striking reticulate hyperpigmentation on photoexposed sites with a sharp cutoff in a V distribution on his anterior chest. Histopathology showed prominent basal degenerative changes, focal lymphocyte exocytosis and an upper dermal lymphohistiocytic infiltrate.

Lichenoid drug eruption associated with imatinib mesylate therapy

INTRODUCTION

Imatinib Mesylate (IM), a tyrosine kinase inhibitor, has been reported to cause several adverse reactions, most of them with cutaneous involvement. Non- Lichenoid IM associated skin reactions have been sufficiently- recorded. To our knowledge, Lichenoid Drug Eruption (LDE) is recorded in a minority of registries.

CASE REPORT

To describe an LDE induced case by IM treatment.

TREATMENT AND OUTCOME

Histological Confirmation and promptly dermatological consultation relieved successfully the cutaneous adverse event.

DISCUSSION

Ongoing expansion of IM usage in a wide spectrum of new indications is more likely to make physicians experience such LDE cutaneous side effects more often. Hence, they should be highly suspicious to early detect these distinct histologic entities, handle these undesired complications and guarantee satisfactory immediate outcomes, avoiding frivolous IM dosage modifications.

A Case Report of Pirfenidone-Induced Lichenoid Drug Eruption in a Patient with Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and lethal lung disease characterized by progressive dyspnea and irreversible loss of lung function. Pirfenidone is a novel anti-fibrotic and anti-inflammatory drug, which reduces deterioration in the lung function and prolongs progression-free survival in patients with IPF. However, it has adverse effects including gastrointestinal symptoms, hepatic dysfunction or skin photosensitivity, and rash. Lichenoid drug eruption (LDE) refers to lichen planus-like drug eruption usually presenting symmetric eczematous plaques with a purple hue. To date, numerous cases of LDE due to various drugs and pirfenidone-associated photosensitivity have been reported. However, a case of pirfenidone-induced LDE has been very rarely reported to our knowledge. Herein, is a case of pirfenidone-induced LDE so that clinicians can be aware of the possibility of LDE when using pirfenidone.

Oxidative Stress in Cutaneous Lichen Planus-A Narrative Review

Lichen planus (LP) is a chronic, immune-mediated inflammatory skin condition that mainly affects the skin (cutaneous LP, CLP) and oral mucosa (oral LP, OLP). However, the mechanisms involved in the pathogenesis of the disease are not fully elucidated. Over time, several theories that could explain the appearance of LP lesions have been postulated. The key players in LP pathogenesis are the inflammatory infiltrate consisting of T cells and the proinflammatory cytokines. The cytokines stimulate the production of reactive oxygen species that induce cell apoptosis, a defining element encountered in LP. The lead inquiry triggered by this revolves around the role of oxidative stress in LP development. There are currently numerous studies showing the involvement of oxidative stress in OLP, but in terms of CLP, data are scarce. In this review, we analyze for the first time the currently existing studies on oxidative stress in CLP and summarize the results in order to assess the role of oxidative stress in skin lesions offering a fresher updated perspective.

Cutaneous Adverse Events of Immune Checkpoint Inhibitors: A Literature Review

Immune checkpoints assist with self-tolerance and minimize collateral tissue damage when immune responses are activated. Although immune checkpoint inhibitors (CPIs) are characterized by a favorable risk/benefit ratio, immune checkpoint blockade has been associated with a new subset of autoimmune-like toxicities, named immune-related adverse events (irAEs). Dermatologic reactions are among the most prevalent irAEs triggered by CPIs. In a majority of cases they are self-limiting and readily manageable. However, it is not uncommon that they result in severe skin involvement and impairment of patients' quality of life. Awareness of the spectrum of cutaneous irAEs is mandatory for every clinician involved in the management of oncologic patients. The role of the dermatologists is essential because early recognition and appropriate management of skin toxicity may prevent dose modifications and discontinuation of CPIs. The latter is particularly relevant, considering that recent data suggest favorable oncologic response in patients developing irAEs.

The new differential diagnostic test for the lichenoid drug eruption

The differential diagnosis between lichenoid drug eruption (LDE) and lichen planus (LP) is difficult due to similar clinical and histological signs but important for treatment and prognosis. The purpose of this study was to propose the new diagnosis method for differentiate LDE from LP. During 2015-2018, 20 patients with confirmed LDE, 13 patients with LP and 134 controls were examined and treated at the Lenoblcenter. All enrolled patients were underwent the injection of 0.5 mL of the 2% lidocaine solution by insulin syringe into the papule with following histological examination. The formation of a blister (bulla) at the site of injection was considered a positive test result. Among LDE, 18 of 20 patients were found positive for developing blister (bulla) and two results were questionable. In 12 of 13 LP patents, bulla on the site of injection was not identified and the result of one patient was nonspecific. All control patients were negative for the proposed test. The histological sections showed that the bulla has corresponded to the separation of the epidermis from the dermis. Intracutaneous injection of 0.5 mL of lidocaine into the papule is an easy highly specific and sensitive method to differentiate LDE from LP.

Fixed drug eruptions, bullous drug eruptions, and lichenoid drug eruptions

Drug reactions are among the most common reasons for inpatient dermatology consultation. These reactions are important to identify because discontinuation of the offending agent may lead to disease remission. With the rising use of immunomodulatory and targeted therapeutics in cancer care and the increased incidence in associated reactions to these drugs, the need for accurate identification and treatment of such eruptions has led to the development of the "oncodermatology" subspecialty of dermatology. Immunobullous drug reactions are a dermatologic urgency, with patients often losing a significant proportion of their epithelial barrier; early diagnosis is critical in these cases to prevent complications and worsening disease. Lichenoid drug reactions have myriad causes and can take several months to occur, often leading to difficulties identifying the offending drug. Fixed drug eruptions can often mimic other systemic eruptions, such as immunobullous disease and Stevens-Johnson syndrome, and must be differentiated from them for effective therapy to be initiated. We review the clinical features, pathogenesis, and treatment of immunobullous, fixed, and lichenoid drug reactions with attention to key clinical features and differential diagnosis.

Necrotic Keratinocytes Are Common in Psoriasis and Have a Predilection to the Upper Epidermis: A Quantitative and Comparative Analysis

BACKGROUND

The most salient histopathological features of psoriasis are epidermal hyperplasia, hypogranulosis, parakeratosis, dilated capillaries in dermal papillae, and intraepidermal and intracorneal neutrophils. Several additional "nonclassic" features of psoriasis have recently been reported, including necrotic keratinocytes (NK). To determine the diagnostic utility of NK, we characterized NK in a large cohort of psoriasis cases compared with psoriasiform spongiotic dermatitis (PSD) and normal skin.

METHODS

NK were quantified in 101 cases of psoriasis, 20 cases of PSD, and 20 cases of normal skin. The location of NK within the lower, middle, or upper thirds of the epidermis was recorded.

RESULTS

NK were identified in 77/101 (76%) of psoriasis cases. By comparison, NK were seen in 8/20 (40%) cases of PSD and 4/20 (20%) cases of normal skin. The linear concentration of NK was significantly higher in psoriasis (0.36 NK/mm) compared with PSD (0.12 NK/mm) and normal skin (0.03 NK/mm) (P = 0.0009). NK were preferentially located in the upper (58%) and middle (31%) epidermis in psoriasis.

CONCLUSIONS

NK are a common feature of psoriasis and have a predilection to the upper layers of epidermis. Superficial NK may provide additional diagnostic support for psoriasis in challenging or borderline cases.

Immunologic adverse reactions of β-blockers and the skin

β-Blockers are a widely utilised class of medication. They have been in use for a variety of systemic disorders including hypertension, heart failure and intention tremors. Their use in dermatology has garnered growing interest with the discovery of their therapeutic effects in the treatment of haemangiomas, their potential positive effects in wound healing, Kaposi sarcoma, melanoma and pyogenic granuloma, and, more recently, pemphigus. Since β-blockers are deployed in a variety of disorders, which have cutaneous co-morbidities such as psoriasis, their pertinence to dermatologists cannot be overstated. Likewise, β-blockers, like any other drug category, carry risks of side effects, some of which are dermatologic. These include triggering and exacerbation of psoriasis, psoriatic and rheumatoid arthritis, anaphylaxis, contact dermatitis, occupational contact dermatitis, Raynaud's disease, alopecia, lichen planus-like drug eruption, hyperhydrosis and vitiligo. While recent articles have focussed on the positive uses of β-blockers, it may also be wise to call our attention to the potential dermatologic adverse effects that may follow β-blocker use, as well as possible therapeutic approaches to these. This short review will focus on those dermatoses resulting from β-blocker use, which have an immunologic basis.

Lichen planus and lichenoid dermatoses: Clinical overview and molecular basis

Deriving from the Greek word λειχήν for "tree moss" and the Latin word planus for "planar," lichen planus is a relatively uncommon and heterogeneous cutaneous disorder that typically develops in middle-aged adults. Despite the significant clinical burden associated with the disorder, little well-conducted molecular research has been undertaken, possibly because of heterogeneity impeding consistent and confident phenotyping. The multiple variants of lichenoid disease bear overlapping clinical and pathologic features despite manifesting as distinct clinical disorders. The first article in this 2-part continuing medical education series provides a comprehensive overview of the clinical and pathologic characteristics of cutaneous lichenoid dermatoses and links these manifestations to recent advances in our understanding of the underlying pathobiology of such diseases.

Adverse Immunologically Mediated Oral Mucosal Reactions to Systemic Medication: Lichenoid Tissue Reaction/Interface Dermatitis-Stomatitis, Autoimmune Vesiculobullous Disease, and IgE-Dependent and Immune Complex Reactions

Drug-induced hypersensitivity immune reactions are exaggerated immunoinflammatory responses to allergenic components of the medications that occur in genetically susceptible subjects. The type of hypersensitivity immune response generated, whether antibody mediated or T cell mediated, or an immune complex reaction is determined by multiple factors, including the molecular characteristics of the allergen, the route of administration of the medication, the manner of presentation of the allergen by antigen-presenting cells to naïve T cells, the repertoire of the T cell receptors, and the cytokine profile within the microenvironment. This review deals with the clinical and histopathological aspects of adverse immunologically mediated oral mucosal reactions to systemic medication. We elaborate on diseases showing features of lichenoid tissue reaction/interface dermatitis-stomatitis, autoimmune vesiculobullous oral lesions, and immunoglobulin E- (IgE-) and immune complex-mediated oral reactions to drugs.

Granzyme B is elevated in autoimmune blistering diseases and cleaves key anchoring proteins of the dermal-epidermal junction

In healthy skin, epidermis and dermis are anchored together at the dermal-epidermal junction (DEJ), a specialized basement membrane pivotal for skin integrity and function. However, increased inflammation in the DEJ is associated with the disruption and separation of this junction and sub-epidermal blistering. Granzyme B (GzmB) is a serine protease secreted by immune cells. Dysregulated inflammation may lead to increased GzmB accumulation and proteolysis in the extracellular milieu. Although elevated GzmB is observed at the level of the DEJ in inflammatory and blistering skin conditions, the present study is the first to explore GzmB in the context of DEJ degradation in autoimmune sub-epidermal blistering. In the present study, GzmB induced separation of the DEJ in healthy human skin. Subsequently, α6/β4 integrin, collagen VII, and collagen XVII were identified as extracellular substrates for GzmB through western blot, and specific cleavage sites were identified by mass spectrometry. In human bullous pemphigoid, dermatitis herpetiformis, and epidermolysis bullosa acquisita, GzmB was elevated at the DEJ when compared to healthy samples, while α6/β4 integrin, collagen VII, and collagen XVII were reduced or absent in the area of blistering. In summary, our results suggest that regardless of the initial causation of sub-epidermal blistering, GzmB activity is a common final pathway that could be amenable to a single targeted treatment approach.

Fenofibrate-Induced Lichenoid Drug Eruption: A Rare Culprit

A lichenoid drug eruption is a rare side effect which can occur following the administration of several different medications. Here we describe a unique case of fenofibrate as the causative agent of a lichenoid drug eruption. This case highlights a rare and clinically significant dermatologic side effect of fenofibrate. In addition, we report a potential familial association which underscores the potential for underlying genetic mechanisms to be contributory to lichenoid drug eruptions. A reminder of the physical characteristics of lichen planus, knowledge of the temporal relation between administration of medications and a lichenoid drug eruption, recognition of the effect of UV exposure on lichenoid drug eruptions, and realization for the potential of symptoms to persist despite discontinuation of an offending agent can aid practitioners in promptly diagnosing lichenoid drug eruptions and initiating appropriate therapy.

Lichen Planus With Predominate Plasma Cell Infiltrate: Two Case Reports

Lichen planus (LP) is a mucocutaneous inflammatory dermatitis of idiopathic origin that can involve the skin, mucous membranes, hair, and nails. LP has an associated set of characteristic histopathologic findings which include hyperkeratosis, vacuolization of the basal layer, Civatte bodies, wedge-shaped hypergranulosis, band-like lymphocytic infiltrate at the dermal epidermal junction, eosinophilic colloid bodies in the papillary dermis, and pigment incontinence. The infiltrate is usually composed of lymphocytes with few histiocytes, mast cells, and macrophages. The presence of plasma cell predominant infiltrate in LP has only been reported in four previous cases and 2 other cases of lichen nitidus. The authors report another 2 cases of LP with predominate plasma cell infiltrate in 2 female patients on the legs. The differential includes a drug-induced lichenoid reaction with predominate plasma cell infiltrate. However, there have been no case reports of that type of reaction. Because plasma cells are seen commonly in certain infectious diseases, malignancy, and macroglobulinemia, it is prudent to rule out those entities. Our patients responded well with a class 1 topical steroid, with improvement of their lower leg lesions within 1 month of treatment.

Clinical, Histopathological Characteristics and Immunohistochemical Findings in Lichen Planus Pigmentosus

Background:

Lichen planus pigmentosus (LPP), a rare variant of lichen planus, is reported in various ethnic groups, more often from the Indian subcontinent and the Middle East.

Aims:

Although the condition is encountered quite often by dermatologists of this region, the data on the clinical, pathological, and immunohistochemical (IHC) aspects of LPP are limited. This prospective study is aimed towards filling this lacuna.

Materials and Methods:

Data were collected from thirty clinically diagnosed cases of LPP who presented to the dermatology outpatient department. Skin biopsy and blood investigations were conducted and the specimens were further analyzed for their histopathological features and IHC staining for CD4⁺, CD8⁺ T-lymphocyte subsets along with CD45RO (UCHL-1), and CD68. The results were statistically analyzed.

Results:

The study showed a female preponderance (56.7%). Photo aggravation as a precipitating cause was seen in 40% of the individuals. The lesions with duration <4 months had a more intense inflammatory infiltrate on histology. CD4⁺ and CD8⁺ cells showed very good Pearsons correlation on statistical analysis. CD45 was seen in association with CD8⁺, and staining for CD68 to assess the macrophage density showed a close correlation with CD45RO.

Limitations:

Small sample size.

Conclusion:

LPP represents a misguided lesional immune response pattern. The intense inflammatory infiltrate seen in the early lesions necessitates prompt treatment to arrest progression which may prevent the chronic pigmentary phase of the disease.

Diagnosis of oral lichen planus: a position paper of the American Academy of Oral and Maxillofacial Pathology

Despite being one of the most common oral mucosal diseases and recognized as early as 1866, oral lichen planus (OLP) is still a disease without a clear etiology or pathogenesis, and with uncertain premalignant potential. More research is urgently needed; however, the research material must be based on an accurate diagnosis. Accurate identification of OLP is often challenging, mandating inclusion of clinico-pathological correlation in the diagnostic process. This article summarizes current knowledge regarding OLP, discusses the challenges of making an accurate diagnosis, and proposes a new set of diagnostic criteria upon which to base future research studies. A checklist is also recommended for clinicians to provide specific information to pathologists when submitting biopsy material. The diagnostic process of OLP requires continued clinical follow-up after initial biopsy, because OLP mimics can manifest, necessitating an additional biopsy for direct immunofluorescence study and/or histopathological evaluation in order to reach a final diagnosis.

Skin Signs of Rheumatoid Arthritis and its Therapy-Induced Cutaneous Side Effects

Rheumatoid arthritis (RA) is a systemic inflammatory disorder that primarily affects the joints, but may exhibit extra-articular, including cutaneous, manifestations such as rheumatoid nodules, rheumatoid vasculitis, granulomatous skin disorders, and neutrophilic dermatoses. A large burden of cutaneous disease may be an indication of RA disease activity and the need for more aggressive treatment. Many of the therapeutic agents used to treat RA can also result in cutaneous adverse effects, which pose their own diagnostic and therapeutic challenges. Anti-TNFα agents, in particular, have a wide variety of adverse effects including psoraisiform eruptions, granulomatous conditions, and cutaneous connective tissue disorders. Herein we provide an update on the clinical presentations and management of RA-associated cutaneous findings as well as drug-induced cutaneous effects, with particular attention to the adverse effects of biologic disease-modifying agents.

Lichen planus and other lichenoid dermatoses: Kids are not just little people

Lichenoid dermatoses, a group of inflammatory skin conditions with characteristic clinical and histopathologic findings, range from common to rare. Classic lichen planus typically presents as pruritic, polygonal, violaceous flat-topped papules and plaques; many variants in morphology and location also exist. Other lichenoid dermatoses share similar clinical presentations and histopathologic findings. These include lichenoid drug eruption, lichen planus-like keratosis, lichen striatus, lichen nitidus, and keratosis lichenoides chronica. Epidemiologic characteristics vary among each lichenoid disorder. While classic lichen planus is considered a disease of adults, other lichenoid dermatoses may be more common in younger populations. The literature contains an array of reports on the variations in presentation and successful management of lichen planus and lichenoid dermatoses among diverse populations. Familiarity with the characteristics of each lichenoid dermatosis, rare or common within each patient population, is key to accomplishing timely recognition and effective management.

[Cutaneous drug reactions imitating dermatoses]

BACKGROUND

Cutaneous adverse drug reactions are frequent and present with heterogenous clinical manifestations.

METHODS AND RESULTS

Increasingly, case reports describe drug reactions which mimic dermatoses, although exact data on prevalence are missing. Psoriasiform, lichenoid and pityriasiform exanthems are most frequent. The differentiation of these variants from the respective authentic dermatoses is difficult and only a few clinical and histological criteria are helpful. Other dermatoses like lupus erythematosus or bullous autoimmune dermatoses (pemphigus vulgaris, bullous pemphigoid) can be induced by drugs as well. These drug-triggered variations are classified as distinct subclasses of the respective dermatosis.

CONCLUSIONS

Exact history and evaluation of the clinical course are essential for the diagnosis of drug reactions mimicking dermatoses and present an important challenge for the clinician. A clear-cut differentiation between the genuine dermatosis and its drug-driven simulator is not always possible.

Transient liver hypoxia after liver hilus dearterialization

Lichen planus (LP) is a chronic inflammatory disorder that most often affects middle-aged adults. LP can involve the skin or mucous membranes including the oral, vulvovaginal, esophageal, laryngeal, and conjunctival mucosa. It has different variants based on the morphology of the lesions and the site of involvement. The literature suggests that certain presentations of the disease such as esophageal or ophthalmological involvement are underdiagnosed. The burden of the disease is higher in some variants including hypertrophic LP and erosive oral LP, which may have a more chronic pattern. LP can significantly affect the quality of life of patients as well. Drugs or contact allergens can cause lichenoid reactions as the main differential diagnosis of LP. LP is a T-cell mediated immunologic disease but the responsible antigen remains unidentified. In this paper, we review the history, epidemiology, and clinical subtypes of LP. We also review the histopathologic aspects of the disease, differential diagnoses, immunopathogenesis, and the clinical and genetic correlations.