Lichenoid Tissue Reaction Research Articles

A Clinicopathological Study on Interface Dermatitis

Background: Interface dermatitis (ID), also known as lichenoid tissue reaction, is a form of skin reaction characterized by an inflammatory infiltration that appears to cover the dermo-epidermal junction under inexpensively analysis. A wide range of inflammatory skin disorders demonstrate interface alteration with significant overlap of histological characteristics. Aim of the Study: The purpose of this study was to link interface dermatitis clinicopathologically. Methods: This cross-sectional descriptive type of study was conducted in the department of dermatology and venereology, TMSS Medical College, Bogura, Bangladesh, from January 2021 to December 2022. The study included 200 patients aged 5 to 75. Skin biopsies were obtained from clinically confirmed cases of lichenoid skin lesions and sent for histological investigation. The correlation was then performed with clinical diagnosis. All acquired data was analysed using descriptive statistics in SPSS 11.5. Results: Out of 200 cases evaluated, the most common type of ID was Lichen simplex chronicus (95, 47.5%), with Lichen planus (LP) and its variants coming in second (84, 42%). LP-like keratosis (15, 7.5%), Inflammatory verrucous epidermal nevus (ILVEN) 2 cases, Pityriasis lichenoides et varioliformisacuta (PLE-VA) 2 cases, and Prurigosimplex (PS) 2 cases were the least prevalent. Clinicopathological concordance was seen in 84 (42%) of the lichen planus patients and discordance in 116 (58%) of the cases. Conclusion: In our investigation, the most consistent histological results were basement membrane degenerations such as lymphocytic infiltrates along the dermo-epidermal interface. Interface dermatitis refers to a group of conditions that share clinical and histological characteristics. As a result, comprehensive histological studies are required to identify distinct features of various kinds of interface dermatitis.

Cytotoxic dermatitis: Review of the interface dermatitis pattern in veterinary skin diseases.

Interface dermatitis or lichenoid interface dermatitis refers to a cutaneous inflammatory pattern in which keratinocyte cell death is the essential feature. These terms have evolved from the originally described lichenoid tissue reaction. These lesions are the basis for an important group of skin diseases in animals and people where cytotoxic T-cell-mediated epidermal damage is a major pathomechanism. Yet, for largely historical reasons these commonly used morphological diagnostic terms do not reflect the essential nature of the lesion. An emphasis on subsidiary lesions, such as the presence of a lichenoid band, and definitions based on anatomical features, such as location at the dermo-epidermal location, may cause confusion and even misdiagnosis. This review covers historical aspects of the terminology, including the origin of terms such as "lichenoid." The types of cell death involved and the histopathologic lesions are described. Etiopathogenesis is discussed in terms of aberrations of immune/inflammatory mechanisms focusing on cutaneous lupus erythematosus, erythema multiforme, and Stevens-Johnson syndrome/toxic epidermal necrolysis. Mechanisms have most extensively been studied in humans and laboratory animals and the discussion is centered on these species. As interface dermatitis is firmly entrenched in dermatological parlance, rather than using "cytotoxic" as its substitute, the terminologies "interface cytotoxic dermatitis" and "panepidermal cytotoxic dermatitis" are recommended, based on location and extent of epithelium affected.

Histomorphological study of lichenoid dermatitides – A retrospective study

Background: Lichenoid dermatitis is a very common dermatological condition and is defined by features of basal cell damage and a dense band-like infiltration at the dermo-epidermal junction. There is a wide range of lesions included under this and the prototype lesion is Lichen Planus. Aims and Objectives: The aims of this study were to study the histopathological spectrum of the conditions with lichenoid tissue reaction and to find clinicopathological concordance of the lichenoid lesions. Materials and Methods: A retrospective study was conducted in a tertiary care center, where all the skin biopsy cases diagnosed clinically and/or histologically as lichenoid dermatitis for 2 years (2018–2019) were included in the study. Demographic details, clinical diagnosis, histological diagnosis, and the different histological features were collected from the respective case sheets and biopsy reports and entered in an excel worksheet. Frequency and percentages were used to represent the data. Results: A total of 47 cases were clinically diagnosed as lichenoid dermatitis, of which 38 cases showed concordance between clinical and histopathological diagnosis. Nine cases showed discordance between clinical and histopathological diagnosis and were categorized as lesions without lichenoid features. Seven cases were diagnosed as lichenoid dermatitis only on the histopathological study with an absence of such a differential diagnosis clinically. Out of the total 45 cases diagnosed as lichenoid dermatitis, 27 were lichen planus, five were lichen planus pigmentosus, four were hypertrophic lichen planus, three were lichenoid dermatitis, and two cases each of lichen planopilaris, lichen keratosis, and lichen sclerosis. Lichenoid dermatitis was seen commonly among the 41–50 years age group. Females were more commonly affected than males. Conclusion: Lichen planus is the prototype lesion among the lichenoid dermatitides. Definitive diagnosis of the specific entity among the lichenoid lesions is important as decision-making regarding the treatment modality and prognosis of the patient depends on it. Histopathological examination is vital for the definitive diagnosis, along with clinical correlation which concludes that clinicopathological correlation is the key.

Nonpruritic hypopigmented macules on an immunocompromised patient

Nonpruritic hypopigmented macules on an immunocompromised patient

Purple-brown coalescing macules on the mandibular area of the face.

This patient presented with a 1-year history of violaceous-brown, coalescing reticulated macules on his face, with no similar lesions in other body areas. Laboratory findings were normal and antinuclear antibody test was negative. Histopathological findings included lichenoid tissue reaction and prominent pigmentary incontinence. Click here for the corresponding questions to this CME article.

Study of clinical and histopathological findings of interface dermatitis and its correlation

Interface dermatitis is a broad term used for all the lesions having clinical features and histological features of epidermal basal cell damage and extensive mononuclear cell infiltration in the papillary dermis, all these lesions are also known as lichenoid dermatosis or “Lichenoid tissue reaction” (LTR).
 The aim of the study was to study in detail histopathological findings associated with interface dermatitis.
 Materials and methods: a total of 112 cases were studied. Material for this study included patients who were clinically diagnosed as having interface Dermatitis from the Department of Dermatology, Gandhi Medical College, Secunderabad, during the period from 2009-2011.
 Results: clinical diagnosis of the 112 cases diagnosed as interface dermatitis in the present study were as follows: The maximum number of cases 44 (39.29 %) were those of Lichen Planus, followed by discoid lupus erythematosus 10 (8.93 %), vitiligo 10 (8.93 %), lichen planus pigmentosus 9 (8.04 %), erythema multiforme 9 (8.04 %), subacute lupus erythematosus 6 (5.36 %), fixed drug eruption 6 (5.36 %), lichen sclerosis et atrophicus 6 (5.36 %), hypertropic lichen planus 6 (5.36 %) and 1 case of linear lichen planus, lichen plano pilaris, lichen nitidus, bullous lichen planus, atrophic lichen planus, lichen amyloidosis, and drug induced lichenoid reaction.
 Conclusion: the interface dermatitis encompasses disease in which there is epidermal basal cell damage, apoptosis of the cell with formation of colloid & civatte bodies, hydropic degeneration of the basal cell, basement membrane thickening, band like or patchy inflammatory infiltrate hugging the dermoepidermal junction and melanin incontinence

Zosteriform lichen planus as a manifestation of Wolf’s isotopic response

Background
 Wolf’s isotopic response has been described in association with malignancy, infections, and inflammatory disorders. Lichenoid tissue reactions are a rare but recognized example of this phenomenon; only 41 cases of zosteriform lichen planus exist in publication. This case adds to the minimal literature describing lichenoid inflammatory dermatosis compatible with Wolf’s isotopic response.
 
 Methods
 Literature review and case description.
 
 Results
 A man in his 30s with a history of herpes zoster presented with a pruritic rash on his left arm. Clinical and histopathological evaluation were consistent with lichen planus in the distribution of a healed herpes zoster rash. The skin lesions improved after six weeks of treatment with clobetasol 0.05% ointment twice daily.
 
 Conclusions
 The presentation of lichen planus as Wolf’s isotopic response is uncommon, but responsive to standard topical therapy.

Application of Cellular Resolution Full-Field Optical Coherence Tomography in vivo for the Diagnosis of Skin Tumours and Inflammatory Skin Diseases: A Pilot Study

Background: Optical coherence tomography (OCT) has been shown to provide non-invasive diagnosis of common skin neoplasms, especially basal cell carcinoma. OCT produces a cross-sectional view of the tissue, similar to a traditionally sectioned histopathological view, but the resolution of conventional OCT is low and thus limits clinical application. Objectives: This study aimed to investigate the application ability of a full-field (FF)OCT system which was newly developed to scan the skin at the cellular level. Methods: Patients with skin tumours or inflammatory lesions warranting biopsy were consecutively enrolled. All lesions underwent clinical, dermoscopic, and OCT assessment, followed by routine biopsy. The adjacent normal skin was scanned for comparison. OCT images were interpreted (blinded to the biopsy results) and then compared with the histopathological diagnosis. Results: A total of 111 patients with 115 lesions completed the protocol, including 80 skin tumours, 28 inflammatory diseases, and 7 other diseases. Of the OCT images, 43.5% were of good quality and show expected features. Identifiable features of actinic keratosis, Bowen’s disease, basal cell carcinoma, extramammary Paget’s disease, seborrheic keratosis, large cell acanthoma, bullous pemphigoid, interface dermatitis, lichenoid tissue reaction, and psoriasis were demonstrated. Lesions are located deeply, and so some features were out of the field of view, accounting for 40.0% (46/115). Conclusions: This study expanded the ability of FFOCT for the clinical diagnosis of various skin conditions. This new optical technique can clearly visualise skin lesions located in the epidermis and upper dermis. It provided an effective way to perform digital skin biopsy in superficial skin diseases.

Treatment of Discoid Lupus Erythematosus in a Dog with Human Intravenous Immunoglobulin

Background: Discoid lupus erythematosus (DLE) is a common canine autoimmune skin disease, in which systemic manifestations are absent. Skin Lesions are usually present on the nasal planum, and characterised by erythema, depigmentation, erosion, ulceration, and crusting. The diagnosis is based on histopathological results, which should demonstrate lymphoplasmacytic lichenoid-interface dermatitis. Human intravenous immunoglobulin (hIVIg) has been used in veterinary medicine to treat cutaneous diseases including erythema multiforme, PF, and severe adverse cutaneous drug reactions. In human medicine, it has been effective to treat DLE. This report firstly describes the clinical response to hIVIg in a dog with DLE resistant to common immunosuppressive drugs.Case: A 5-year-old, intact female Shih Tzu presented with a 1-month history of slowly progressive black crusting on the nasal planum, chin, and claw. Based on the results of a dermatologic examination, superficial pyoderma was diagnosed. The skin lesions did not improve during and after anti-infective treatment. After removing the crusts, a skin biopsy was obtained from the muzzle. Histopathology of lesional skin biopsy specimens revealed lymphoplasmacytic interface dermatitis at the dermoepidermal junction. Microscopic examination also revealed vacuolar changes and pigmentary incontinence of the basal layer as a lichenoid tissue reaction. No mites or fungi were detected on the skin section. The absence of acantholytic cells excluded pemphigus foliaceus, which is also characterised by the lesions of the nasal planum. Based on the distribution of the lesions, histopathology and exclusion of other dermatoses, the dog was diagnosed with DLE. The skin lesions temporarily improved after treatment with prednisolone (2 mg/kg PO q12h). However, after tapering the dose of prednisolone, new black crusts developed on the nasal planum and claw. Although the dog was successively treated with other immunosuppressive drugs, including azathioprine, cyclosporin with dexamethasone, and mycophenolate mofetil, black crusts still remained. Due to the low efficacy of these immunosuppressive drugs, hIVIg was administered at 0.5 g/kg once daily for 4 days, for a total dose of 2 g/kg. During hIVIg administration, the crusted lesions gradually improved. After the hIVIg administration, the dog was treated with prednisolone (1 mg/kg PO q12h). The lesions were almost in complete remission at 21 days after an additional application of prednisolone. The skin lesions did not recur, and the treatment was eventually discontinued after 6 weeks of additional prednisolone application.Discussion: The standard treatment of canine DLE includes glucocorticoids, and second-line immunosuppressive drugs, such as azathioprine and cyclosporine, are usually added in cases resistant to steroids. This case suggests that hIVIg may be beneficial as an adjunctive treatment option for canine DLE, especially when the application of standard immunosuppressive drugs is limited due to adverse effects or low efficacy. There is evidence from several studies that the steroid-sparing effect of hIVIg is significant in human patients. In the current case, the effective dose of prednisolone was reduced to 2 mg/kg/day after hIVIg administration, and prednisolone therapy was finally discontinued completely. The hIVIg appears to lower the daily steroid dose requirement in this dog. Keywords: autoimmune skin disease, discoid lupus erythematosus, canine dermatology, immunosuppressive drug, human intravenous immunoglobulin.

Lichenoid dermatoses involving the vulva: A clinical-pathologic correlation✰.

The lichenoid tissue reaction pattern generally signifies cytotoxic damage to the epithelium. When such reaction pattern occurs on vulvar skin or mucosa, the effects can result in considerable morbidity. None of the entities discussed in this review are entirely unique to the vulva, however, some entities may classically occur at this site, while others tend to be widespread diseases that may incidentally affect vulvar skin and mucosa. Given the complex anatomy of the vulva and the bridging of a site showing both keratinizing squamous epithelium and non-keratinizing squamous mucosa, histopathologic features may display variation in presentation. Although identification of a "lichenoid reaction pattern" alone may provide insight into the disease process, understanding of clinical presentation and specific sites of involvement, along with recognition of the nuanced features of the disease entities can help establish a specific diagnosis. Accurate histopathologic diagnoses by pathologists can improve the ability for treating clinicians to implement timely and effective treatment.

An unusual variant of lichen nitidus: Generalized follicular spinous with perifollicular granulomas

Several unusual variants of lichen nitidus are described in the literature. Spinous follicular lichen nitidus with perifollicular granulomas is one such variant characterized by generalized follicular as well as nonfollicular keratotic papules, which show perifollicular granulomas on histopathology as well as a lichenoid granulomatous tissue reaction typical of lichen nitidus. Owing to its atypical clinical and histopathologic manifestations, it raises several clinical possibilities and can be a diagnostic challenge. We report this rare variant of lichen nitidus in a 19-year-old female, and discuss its clinical and histopathological differential diagnosis.

Clinicohistopathologic study of lichenoid interface dermatitis

Background: Interface dermatitis (IFD)/lichenoid tissue reactions are among the most frequently presenting disorders in dermatology, which in common have a constellation of histopathological features but varied clinical presentation. Aim: Clinicopathologic correlation and determination of histomorphologic changes associated with various lichenoid IFD of the skin. Materials and Methods: This was a prospective study with purposive sampling of patients reporting to the outpatient department of dermatology, venerology, and leprosy of our hospital from January 2017 to July 2018. Skin biopsies of 150 patients of either sex diagnosed provisionally as one of the lichenoid IFD on clinical grounds were studied. Clinicohistopathologic correlation was done. Results: We encountered 58 cases of classic lichen planus, seven variants of lichen planus (hypertrophic lichen planus, ashy dermatosis, lichen planus pigmentosus, actinic lichen planus, lichen planopilaris, lichen nitidus, and lichen striatus), and 16 cases of lichenoid eruptions. About 82.6% of the cases were concordant histopathologically. The peak incidence was in 20–40 years of age with an equal predilection for males and females. A majority of the lesions were multiple, pruritic, papules, and plaques involving the limbs. Histopathologically, the most consistent findings were basal cell vacuolar degeneration followed by melanin incontinence. Conclusion: Lichenoid IFDs are exclusive clinicopathological entities with several variants. Subtle features noted on histopathology help in differentiating these lesions. Understanding and interpreting these subtle changes aids in better clinical management of the patient.

Lichenoid eruptions in children: A retrospective study

Background: Lichenoid eruptions are a diverse group of inflammatory dermatoses, characterized clinically by flat-topped papules which resemble lichen planus (LP) and histologically by a lichenoid tissue reaction. There are many lichenoid dermatoses, of which some are seen predominantly in the pediatric age group. The knowledge of these lichenoid eruptions is essential for the dermatologists for early diagnosis, timely treatment, and also to predict their course. Aims: Our aim was to study the clinicoepidemiological features of lichenoid dermatoses in children and to differentiate between various lichenoid dermatoses and classify them accordingly. Materials and Methods: This was a retrospective, hospital-based, cross-sectional study of 52 children with a clinical diagnosis of lichenoid eruptions from January 2017 to December 2017. Results: Of the 986 children who visited the dermatology outpatient department 52 children (5.27%) were diagnosed with lichenoid dermatoses, with the male: female ratio being 1: 1.48 and a mean age of 7.25 years. LP was the most common lichenoid dermatosis reported in our study (48%), followed by lichen striatus (37.6%), lichen nitidus (5.8%), lichen sclerosus (5.8%), pityriasis lichenoides (3.2%), and Gianotti Crosti syndrome (1.9%). Limitations: It was a retrospective data analysis involving only 1 year of study with limited sample size, without study of long term evolution. Conclusions: Some lichenoid dermatoses (lichen straitus and lichen nitidus) are self-limiting and undergo spontaneous resolution without any sequelae, whereas LP and lichen sclerosus can be associated with varying degrees of morbidity. Proper diagnosis helps in allaying the fears of parents.

Clinical profile and Histopathological spectrum of Interface Dermatitis

Background- Interface Dermatitis is an etiologically diverse and poorly understood group of skin diseases characterized by pathology at the dermo-epidermal junction. The prototype disease is Lichen Planus but there are many other disease entities that exhibit Lichenoid tissue reaction / Interface changes. Aims- To study the clinical profile and Histopathological spectrum of Interface Dermatitis. Materials & Methods- This was a prospective study conducted at a tertiary care hospital over a period of eighteen months. A total of Ninety-eight cases clinically suggestive of diseases believed to show interface changes on histology were studied. Clinical details were recorded. Skin biopsies were taken from representative lesions. H&E stained sections were studied in detail for diagnosis and subtyping. Analysis was done in percentages and proportions. Results- Fifty-three cases (54%) showed IFD on histopathological examination. The most common age range was between 11-40 years and both the sexes were equally affected. Majority of the cases clinically presented as papules and plaques. The most common type of IFD were LP and its variants (52.1%). The most consistent microscopic findings were vacuolar degeneration of basal layer, pigment incontinence and inflammatory infiltrate around DEJ and blood vessels. Conclusions- IFD includes various diseases which have overlapping clinical as well as histopathological features. A detailed histopathological examination and correlation of the interface changes with clinical diagnosis is helpful in arriving at a definitive diagnosis which is essential for predicting the course of the disease and its optimal management.

Five year descriptive study of the histomorphological features of lichen planus

Background: Lichen planus is a chronic or sub-acute disorder characterized by small, flat-topped, shiny, erythematous or violaceous, pruritic polygonal papules most commonly involving the wrists and/or ankles in symmetric fashion. The spectrum of clinical diseases related to the lichenoid tissue reaction is getting wider with a recent increase in new subgroups of the lichenoid clinical picture. Lichen Planus contributes to the major bulk of cases of lichenoid tissue reactions. This study is designed to study the histopathology of clinical variants of lichen planus and its distribution in relation to age, sex and site of lesion. Objectives of the study: To study the histopathological features of lichen planus and its variants and clinicopathological correlation with respect to age and sex. Methods: This study was carried out over 5 years (retro and prospective) at Mahadevappa Rampure Medical College, Kalaburagi on clinically diagnosed cases of lichen planus. The tissue was fixed in 10% formalin and paraffin embedded sections were obtained for microscopic examination. Results: We studied 107 skin biopsy specimens. The variants of lichen planus received were classical lichen planus (55), hypertrophic lichen planus (27), follicular lichen planus (12), actinic lichen planus (6), isolated oral lichen planus (3), lichen planus pigmentosus (3), lichen planus pemphigoides (1). Maximum number of cases occurred in 2nd decade (29.9%). A slight female preponderance was noted (53.2%). Extremities were the most common site affected in 59 cases (55.1%). Conclusion: Lichen planus presents with varied morphology and microscopy, hence detailed clinical examination with data collection and proper histopathological examination is necessary for categorization and understanding of lichen planus and differentiation from various, diverse and perplexing lichenoid tissue reactions.

Late-onset pseudoepitheliomatous hyperplasia developing within a red ink tattoo

The popularity of tattoos has increased dramatically worldwide particularly in the last three decades, giving rise to the frequent occurrence of a wide spectrum of secondary cutaneous and systemic complications. Pseudoepitheliomatous hyperplasia (PEH) is a benign irregular hyperplasia of the epidermis occurring in response to various stimuli, that clinically and histopathologically resembles cutaneous neoplasms such as squamous cell carcinoma and keratoacanthoma. In an attempt to improve the awareness of the possible occurrence of PEH in tattoos and of its diagnostic and therapeutic aspects, we present herein the case of a 30-year-old woman with histologically confirmed PEH related to a red-ink tattoo. She revealed two important features: the longest interval reported so far between tattooing and onset of PEH (two years) and the lack of the otherwise very common lichenoid tissue reaction to red ink. In view of the serious toxicological potential of tattoo inks, implementation of updated and standardized regulations worldwide regarding their use in the tattooing process is now urgently warranted and continuous efforts should be undertaken in order to enhance the awareness among tattoo artists and the public with regard to the possible serious health risks associated with the use of tattoo ink pigments.

Classic and Hypertrophic Vulvar Lichen Planus.

ObjectivesThree types of lichen planus (LP) occur on the vulva: erosive, classic, and hypertrophic. The latter 2 occur on keratinized skin and little is known about their clinicopathologic appearance.Materials and MethodsVulvar biopsies of keratinized skin reported as LP or “lichenoid” between 2011 and 2017 were reviewed. Inclusion required age of older than 18 years, a lichenoid tissue reaction, and insufficient abnormal dermal collagen to diagnose lichen sclerosus. Clinical and histopathologic data were collected and cases were categorized as hypertrophic, classic, or nonspecific lichenoid dermatosis. Descriptive statistics were performed and groups were compared with the Fisher exact test.ResultsSixty-three cases met criteria for inclusion. Twenty-nine (46%) cases were categorized as hypertrophic LP, 21 (33%) as classic LP, and 13 (21%) as nonspecific lichenoid dermatosis. There were no significant differences in age, primary symptom, biopsy location, or duration of disease between the 3 groups. When compared with classic and nonspecific disease, hypertrophic LP was less likely to have comorbid dermatoses and more likely to be red, diffuse, have scale crust, and contain plasma cells in the infiltrate. Nonspecific disease had similar clinical features to classic LP but was less likely than the other 2 categories to have a dense lymphocytic infiltrate and exocytosis.ConclusionsVulvar LP on keratinized skin has a diversity of appearances and presents a clinicopathologic challenge. Further research is required to understand the natural history of hypertrophic LP and the underlying diagnosis of nonspecific lichenoid cases.

Mogamulizumab-induced photosensitivity in patients with mycosis fungoides and other T-cell neoplasms.

Mogamulizumab (Mog) is a defucosylated, therapeutic monoclonal antibody, targeting CCR4 and was first approved in Japan for the treatment of adult T-cell leukaemia/lymphoma (ATLL), followed by cutaneous T-cell lymphoma and peripheral T-cell lymphoma. To retrospectively investigate development of photosensitivity in patients with mycosis fungoides and other T-cell neoplasms after treatment with Mog. We treated seven cutaneous lymphoma patients with Mog. Upon combination treatment with narrow-band UVB, we noticed that four patients developed photosensitivity dermatitis following Mog therapy, including two cases of mycosis fungoides, one case of adult T-cell leukaemia/lymphoma and one case of EB virus-associated T-cell lymphoproliferative disorder. Phototest was performed with UVA and UVB, and immunohistochemical staining for CD4, CD8 and Foxp3 was conducted in both photosensitivity and lymphoma lesions. Phototest revealed that the action spectrum of the photosensitivity was UVB in three cases and both UVB and UVA in one case. Histopathologically, the photosensitive lesions were characterized by a lichenoid tissue reaction with a CD8+ T cell-dominant infiltrate, sharing the feature with chronic actinic dermatitis, an autoreactive photodermatosis with a cytotoxic T-cell response. Foxp3+ regulatory T cells (Tregs) were decreased in the photosensitivity lesions compared with the lymphoma lesions. Increased incidence of photosensitivity reaction was observed during Mog treatment. Decreased number of Tregs in the lesional skin suggests that this reaction is possibly induced by autoreactive cytotoxic T cells.

A Rare Form of Lichenoid Tissue Reaction: Lichenoid Granulomatous Dermatitis

Interface dermatitis is characterized by inflammatory infiltration dermoepidermal junction and defined as lichenoid tissue reaction. This histopathological appearance and pathophysiological process are mainly observed in lichen planus, lichenoid drug reaction, lichenoid autoimmune connective tissue disease, lichenoid purpura and lichenoid granulomatosis dermatitis. In this case, we report a 51-year-old female patient, diagnosed with lichenoid granulomatous dermatitis concurrence with myasthenia gravis and thymoma. J Med Cases. 2015;6(2):95-97 doi: http://dx.doi.org/10.14740/jmc2031w

表皮角化細胞死を伴う苔癬反応（Lichenoid tissue reaction）/Interface dermatitisを呈する皮膚粘膜疾患とマウスモデル

A set of histopathological elements with death of epidermal basal cell layer keratinocytes along with inflammatory cell infiltration distinguishes lichenoid tissue reaction (LTR)/interface dermatitis (IFD) from other inflammatory mucocutaneous diseases. The LTR/IFD can be seen in skin disorders like as lichen planus, acute graft-versus-host disease, lupus erythematosus, dermatomyositis, and toxic epidermal necrolysis/Stevesn-Johnson syndrome. Clinical and basic researches suggested that cytotoxic CD8 T cells producing interferon-γ and FasL are final effector cells to cause apoptosis of keratinocyte. Some murine models of LTR/IFD have been established, for example, LTR/IFD reactions of keratinocyte-specific ovalbumin (OVA)-transgenic mice after OVA-specific T-cell-receptor(+)CD8 T cells. By analysis of the murine model, a new class of immunosuppressant, a JAK inhibitor, has been suggested as a new candidate for treatment of LTR/IFD.