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Inroduction: Major role of a dermatopathologists is to try to make specific diagnosis of inflammatory skin diseases. IFD means inflammatory infiltrate that abuts or obscures the dermo-epidermal junction in askin biopsy.This type of reaction is also seen in skin disorders associated with systemic illness like LE and skin changes of potentially fatal disorders such as Graft versus host disease, S-J syndrome and toxic epidermal necrolysis. Aims & Objectives- 1) To study the histopathology of interface dermatitis.(2)To study the common types of skin manifestations in interface dermatitis.(3)To determine other histological features associated with interface dermatitis.4)To identify the clinical concordance of various types of interface dermatitis. Methods : Present study is a retrospective , Hospital based study. Ethical consideration was taken. Study duration was Jan 2012 to Dec 2015. Results: In the present study, a total of 121 cases of IFD were studied, the majority of which [65] presented as papulo- squamous [ papules and plaques ] lesions. Of theses 121 cases, the most common type of IFD was LP and its variants (53.71 %).The next common was LDE (8.26 %) followed by PL(7.4% ). The least common was LN (0.8 % ) and dermatomyositis (1.6 %). Female preponderance was noted in case of IFD [ 59.9 % ]. The percentage of clinical concordance was good in cases of LP & its variants (90.77 %), DLE ( 83.33%) and in Dermatomyositis. Conclusion - A good clinicopathologic correlation is absolutely essential for the final diagnosis of IFD. DOI: 10.21276/AABS.1460

Background There are conflicting reports on the association between interface dermatitis and hepatic involvement in DRESS. Methods A cross-sectional analysis of the clinical and the histopathology features of DRESS was performed to study the association between the histopathology of the skin rash and hepatic involvement. Results The clinical and the histopathology findings were evaluated in forty cases of DRESS. Thirty patients (75%) had a hepatic involvement. Thirty (75%) biopsy specimens showed a combination of different inflammatory patterns. The interface dermatitis was noted in 24 specimens (60%). Twenty-one patients with the interface dermatitis had a hepatic involvement (P = 0.04). Conclusions The skin rash of DRESS often shows the coexistence of different inflammatory patterns. The interface dermatitis showed a statistically significant association with the hepatic involvement in DRESS.

Riehl melanosis (RM) is a form of pigmented contact dermatitis that often poses a diagnostic challenge due to overlaps in its clinical, dermoscopic, and histopathological features with other pigmentary disorders. This report highlights significant findings and the proper approach for diagnosis. We present the case of a 47-year-old female with progressive facial hyperpigmentation (irregular, blotchy, grayish patches on the forehead, cheeks, and around the mouth) that acknowledged applying a lightening product before her complaint. Dermoscopy revealed brownish-gray dots and pseudonetwork pigmentation. The histopathological findings were comprised of hypergranulosis, interface dermatitis, and pigment incontinence. The patient's history and clinical, dermoscopic, and histopathological examination results showed features consistent with-but not exclusive to-RM, such that it was not possible to rule out lichen planus pigmentosus (LPP) and ashy dermatosis (AD). We finally diagnosed the patient with RM and treated her with medications consisting of alpha hydroxy acid, tretinoin, hydroquinone, and sunscreen. Patch testing might help because higher positivity rates were found in RM patients compared to LPP and AD. However, positive patch testing favors RM, and, regardless of diagnosis, provides a basis for substance avoidance in the treatment plan.

Background Reflectance confocal microscopy (RCM) is a non-invasive imaging technique that provides dynamic information and allows in vivo monitoring, with excellent histologic correlation. In the last decade, the use of RCM for cutaneous T-cell lymphomas (CTCL) has been reported. CTCL may require multiple biopsies for diagnosis due to its equivocal clinical presentation. RCM was described as a possible tool to help determine the best site for skin biopsy. This study aims to systematically review all RCM features reported in literature for CTCL. Method A systematic literature search concerning CTCL evaluated by RCM was performed in eight electronic databases until May 2019 following PRISMA-DTA quality assessment. Results Eighteen RCM features were described in patients with CTCL. The most frequent were: interface dermatitis (89%), epidermal lymphocytes (82%), epidermal architectural disarray (81%), and vesicle-like structure (Pautrier microabscess) (51%). Conclusion In order to establish comparable parameters among the studies identified, we proposed descriptors for CTCL features and a grading system to quantify them. This will facilitate to define the role of RCM in the diagnosis and monitoring of CTCL patients.

ZusammenfassungDieser Übersichtsartikel stellt das komplexe Krankheitsbild Erythema multiforme bei Hund und Katze dar. Es werden Ätiologie, Pathogenese, klinische Symptomatik, Diagnostik und Therapie erläutert. Erythema multiforme ist eine seltene, immunmediierte Hauterkrankung mit einem akut auftretenden spezifischen Reaktionsmuster der Haut und Schleimhaut auf unterschiedliche zugrundeliegende Mechanismen. Als auslösende Faktoren wurden Medikamente, Futtermittelbestandteile und Neoplasien, aber auch virale oder bakterielle Infektionen sowie Impfreaktionen identifiziert. In über 20% der Fälle lässt sich das auslösende Agens jedoch nicht eindeutig feststellen. Der Deutsche Schäferhund sowie der Pembroke Welsh Corgi scheinen prädisponierte Hunderassen zu sein. Häufig werden bei Hunden erythematöse Makulae, geringgradig erhabene und sich peripher ausbreitende Papeln sowie ringförmige bis bogenförmige erythematöse Muster beschrieben. Quaddeln, Plaques, Vesikel und Bullae, die sich zu Ulzerationen entwickeln, treten ebenfalls zeitweise auf. Häufig betroffene Körperregionen beim Hund sind Ventrum, mukokutane Übergänge, Maulhöhle, Pinnae und Pfotenballen. Histopathologische Befunde umfassen meist Einzelzellnekrosen in mehreren Schichten der Epidermis mit lymphozytärer Satellitose und einer zellarmen Grenzzonendermatitis. Eine Elimination der ursächlichen Faktoren und gleichzeitige symptomatische Therapie werden empfohlen. Die Prognose des Erythema multiforme variiert von vorsichtig bis günstig, je nach zugrundeliegender Ursache, Ausprägungsform und Ansprechen auf die Behandlung.

Lichen planus (LP) is a classic skin disease that can involve the skin, hair, and nails, as well as the oral and genital mucosa. Histopathology is characterized by a T-lymphocytic, lichenoid, and interface dermatitis. Multiple case reports and small case series have shown that LP can involve the esophagus. However, the diagnostic criteria, incidence, and best treatment options remain uncertain. This study aimed to refine the diagnostic criteria, estimate prevalence, and present an outlook on treatment options to prevent long-term sequelae.Thirty-two consecutive patients with LP of the skin, hair, nails, oral mucosa, and/or genital mucosa underwent a comprehensive clinicopathologic assessment. Esophagogastroduodenoscopy was performed, and biopsies were evaluated histologically, immunohistochemically, and by direct immunofluorescence. Patients diagnosed with esophageal lichen planus (ELP) were followed up prospectively where possible.In total, 20 of 32 patients had ELP. Ten of these 20 patients were classified as having proven ELP, with clear-cut endoscopically visible lesions; the other 10 were classified as having probable ELP. Eight of 10 patients with proven ELP were started on new or additional therapy because of esophageal findings. Treatment with a topical budesonide formulation or systemic corticosteroids was successful in most patients with proven ELP and reversed functional esophageal stenosis.ELP can be found in more than 50% of patients with proven mucocutaneous LP when clinical and pathologic findings are correlated carefully. Topical or systemic corticosteroids are the first-line therapy for ELP. Timely medical therapy seems to prevent scarring stenosis of the esophagus.

Introduction The histologic features of autoimmune progesterone dermatitis are generally non-specific and have only been described in brief case reports. We present a case of autoimmune progesterone dermatitis and review the literature with a focus on the histologic findings described. Methods A review of the English literature on autoimmune progesterone dermatitis was performed using PubMed and MEDLINE. Results 39 patients, including our patient are included in this review. The most consistent histologic finding reported was a perivascular inflammatory infiltrate, being seen in 72% of cases. A non-specific or interstitial inflammatory infiltrate was described in 31% of the cases, with 41% having an eosinophilic component and 21% having a neutrophilic component mixed with the predominant lymphocytic infiltrate. Interface dermatitis was the second most common finding with 36% demonstrating a mild to exaggerated interface dermatitis. Conclusion Although histopathologic changes are non-specific, perivascular dermatitis with eosinophils and interface changes are common in autoimmune progesterone dermatitis.

Context Lichenoid interface dermatitis refers to the histological pattern which is useful for the classification and diagnosis of disorders of a particular group in dermatology with peculiar features. Aims To get clinico pathological correlation in lichenoid interface dermatitis which will help in accurate diagnosis by analyzing history, clinical examination as well as histological details of nature and extent of epidermal, interface and dermal changes and the distribution of various inflammatory cell infiltrates. Methods After appropriate case selection according to the inclusion criteria, the biopsy was taken and sent for histopathological analysis. It was reviewed and correlation was done in each patient. Statistical analysis used: kappa correlation analysis. Results Out of total 117 cases, 108 were of lichen planus, five were of lichen striatus, two of lichenoid drug eruptions and two of lichen nitidus. Clinico-pathological correlation was present in 70.94% of cases of lichenoid interface dermatitis. Correlation was seen in 100% cases of lichen striatus, and 78% cases of lichen planus. Conclusions The most consistent findings in histology in our study were basement membrane degeneration, band like lymphocytic infiltrates and melanin incontinence. Other findings such as hypergranulosis, civatte bodies were not observed frequently.

Palmoplantar lesions of secondary syphilis are often termed "syphilis cornee." A 32-year-old male presented with itchy lichenoid papules on both soles and left palm associated with grayish white papules on the buccal mucosa and glans penis. Initial clinical diagnosis of palmoplantar lichen planus with mucosal involvement was supported by the histopathological finding of interface dermatitis. However, more detailed history, serological tests of syphilis, and review of histopathological findings led us to revise the diagnosis as syphilis cornee. This case highlights the uncommon presentation of syphilis cornee as pruritic palmoplantar lichenoid papules with histology showing interface dermatitis. A high index of clinical suspicion of secondary syphilis is needed as its manifestations are often deceptive.

Acquired dermal macular hyperpigmentation (ADMH) is an umbrella term that includes disorders clinically characterized by small and large pigmented macules/patches and histopathologically showing an evidence of current or resolved interface dermatitis with pigment incontinence, without clinically significant prior inflammatory phase. The term intends to include diseases previously described in the literature as lichen planus pigmentosus, Riehl's melanosis/pigmented cosmetic dermatitis and ashy dermatosis/erythema dyschromicum perstans. The nomenclature and origin of these disorders have always been a matter of discussion. These disorders share many clinicopathological similarities, are difficult to treat and adversely affect the quality of life. Recent consensus points towards the need for a unifying term to facilitate research and therapeutic trials. This article aims to provide a comprehensive review of the recent advances in ADMH.

Ipilimumab is an immune-modulating drug that is being used today for various cancers including metastatic malignant melanoma. Owing to its mechanism of action, several adverse events have been reported, including some affecting skin. In this work, we report a novel display of multiple ipilimumab-associated halo lichenoid reactions surrounding benign nevi during treatment of metastatic melanoma. A patient underwent treatment with ipilimumab for treatment of stage IIIC melanoma at our center and was monitored for progress and adverse events throughout treatment. During treatment with ipilimumab, the patient clinically developed multiple halo lichenoid reactions surrounding previously present nevi, which histopathologically showed a lichenoid interface dermatitis associated with the mildly atypical nevi and ill-formed granulomata within the infiltrate. Therefore, ipilimumab may be associated with halo lichenoid reactions surrounding benign nevi and this adverse effect should be added to the various dermatologic reactions that patients can develop while being treated with this agent.

Background: Direct immunofluorescence (DIF) test for tissue-bound autoantibodies, has been found to be of value in the diagnosis of several dermatological disorders. The location and pattern of deposition of immunoreactants helps in classifying various immune-mediated diseases. Aims and Objectives: The aim of this study was to analyze the concordance between the clinical, histopathological and DIF diagnosis in bullous and nonbullous lesions of the skin, and thus determine the impact of immunofluorescence on diagnosis. Materials and Methods: A total of 215 skin biopsies performed in suspected immune-mediated vesiculobullous disease, vasculitis or dermatosis, were studied. Histopathological examination was done along with DIF study for deposits of immunoglobulin G(IgG), IgA, IgM, and C3. Results: Direct immunofluorescence was positive in 103/215 cases. There was very good concordance between the clinical, histological and DIF results (observed agreement = 93.4%, κ =0.90, with 95% confidence interval = 0.86–0.94). The overall sensitivity of DIF in immune-mediated skin disorders was 98.0%. DIF was positive in 52/53 cases (98.1%) in the pemphigus group and 24/25 (96.0%) bullous pemphigoid cases. None of the clinically suspected cases of dermatitis herpetiformis showed DIF positivity. A positive lupus band test was seen in 9/9 (100%) cases of lupus erythematosus. DIF was positive in 10/10 (100%) clinically suspected cases of Henoch–Schönlein purpura. In 110 cases, negative DIF results helped to rule out immune-mediated vesiculobullous disorders, lupus erythematosus and vasculitis, and the final diagnosis was made on the basis of the clinical features and/or histopathology. Conclusion: Direct immunofluorescence is a useful supplement for the accurate diagnosis of immune-mediated dermatological disorders, and helps to classify various autoimmune bullous disorders. When the clinical features/histopathology are inconclusive, the diagnosis often can be made on the basis of the DIF findings alone. A combination of the clinical features, histopathology and DIF usually gives the best results.

Linear dermatoses are fascinating entities that likely reflect embryologically derived cutaneous mosaicism, even when they occur after childhood. Adult blaschkitis is a rare, relapsing inflammatory dermatitis that most often presents in middle age. It presents clinically as a pruritic eruption of linear papules, vesicles and plaques, and is most commonly found to have features of spongiotic dermatitis on pathology. However, the clinical and histopathologic presentation of lichen striatus in adults may be similar to those of adult blaschkitis. A case in which 'blaschkitis' was suspected clinically is presented, in which the biopsy showed non-characteristic microscopic features resembling erythema multiforme--a finding rarely reported in the literature to date. We present this case and a brief review of the most commonly acquired linear eruptions following Blaschko's lines with the goal of expanding the histopathologic findings that may be encountered in adult blaschkitis. Moreover, the clinical and histopathologic overlap between the entities of blaschkitis and lichen striatus is explored, acknowledging that these entities may exist on a clinicopathologic spectrum. In the diagnosis of linear eruptions, clinicopathologic correlation is important for arriving at an accurate final diagnosis.

Background: Lichenoid tissue reaction/Interface dermatitis (LTR/ID) refers to a number of clinically diverse, poorly understood and relatively uncommon inflammatory skin diseases. This study was done to understand the histopathological features of lichenoid tissue reactions in skin biopsies and to assess the concordance and disparity between the clinical and histopathological diagnosis of variants of the same.Methods: It was a 3½ years study from January 2014 to June 2017 in the department of Pathology, KIMS, Hubballi. The present study included skin biopsies of clinically diagnosed and suspected cases and histologically diagnosed cases of LTRs. Skin biopsies received were routinely paraffin processed and H&E stained to study the microscopic features.Results: Out of 166 skin biopsies studied, 148 were histologically confirmed as LTR with majority being of lichen planus (LP) (91.22%). Classical lichen planus was the most common variant of lichen planus among lichen planus cases. Male:female ratio was 1.2:1. Clinico-pathological concordance was seen in 88.55% of the cases.Conclusions: Though definite diagnosis can be made on histopathological examination, size of specimen, site of biopsy, nature and depth of biopsy, quality of sections, treatment history and inter-observer variation (both clinically and histologically) should be kept in mind which may lead to clinicopathological discordance.

Zoledronic acid (ZA) is a bisphosphonate given intravenously, most commonly for the treatment of postmenopausal osteoporosis. Increase in usage of ZA because it was FDA-approved has resulted in increasing reports of side effects. For the most part, these are systemic. Cutaneous side effects associated with ZA are infrequent and limited to 2 reports of dermatomyositis to date. In both, patients presented with clinical and laboratory stigmata of dermatomyositis soon after initiation of therapy. In this report, we describe a 62-year-old woman who presented with diffuse, erythematous scaly plaques over the right thigh after 12 hours of infusion of ZA. Histopathologic examination of a skin biopsy from the right thigh revealed patchy scale crust containing neutrophils and inspissated serum, interface change with scattered individually necrotic keratinocytes, and a mild, superficial perivascular lymphocytic infiltrate with scattered eosinophils and pigment incontinence—findings consistent with an interface dermatitis. Given that the patient had no other systemic manifestations or laboratory abnormalities, to the best of our knowledge, ours is the first report of interface dermatitis secondary to ZA with the caveat that longer follow-up is required to definitively exclude the development of drug-induced connective tissue disease.

Common inflammatory skin diseases can be correctly diagnosed with clinical examination. However, unusual presentations do exist and may cause difficulties in the differentiation among different entities, and histopathology is required for an accurate diagnosis. In this regard, dermoscopy and reflectance confocal microscopy (RCM) can play an important role in increasing the specificity of the diagnosis, offering the possibility of improved management of patients. In this review, the authors have analyzed dermoscopic patterns of lichen planus, discoid lupus erythematosus, psoriasis and alopecias as prototypes of inflammatory skin diseases, and correlated them with RCM microscopical features. RCM, thanks to its correspondence to histology and to the possibility of an immediate correlation to dermoscopy, provides additional information useful for increasing the sensibility and specificity of dermoscopy.

Vitiligo, particularly the rarer inflammatory variant, may be difficult to distinguish from hypopigmented mycosis fungoides (MF) clinically. Complicating the distinction is that when biopsies are taken from the periphery of early vitiliginous lesions or from lesions with an inflammatory border (inflammatory vitiligo), a dermal lymphocytic infiltrate, exocytosis, interface dermatitis, and mild spongiosis may be seen, all resembling the findings seen in hypopigmented MF. We present a case demonstrating the difficulty in differentiating between these two diseases and examine some characteristic clinical and histopathological features of each. Often, a conclusive diagnosis cannot be made, necessitating close follow-up of the patient and monitoring for progression of their disease over time.

Background: Benign lichenoid keratosis (BLK, LPLK) is often misdiagnosed clinically as superficial basal-cell carcinoma (BCC), especially when occurring on the trunk. However, BCCs undergoing regression may be associated with a lichenoid interface dermatitis that may be misinterpreted as BLK in histopathologic sections. Methods: In order to assess the frequency of remnants of BCC in lesions interpreted as BLK, we performed step sections on 100 lesions from the trunk of male patients that had been diagnosed as BLK. Results: Deeper sections revealed remnants of superficial BCC in five and remnants of a melanocytic nevus in two specimens. In the original sections of cases in which a BCC showed up, crusts tended to be more common, whereas vacuolar changes at the dermo-epidermal junction and melanophages in the papillary dermis tended to be less common and less pronounced. Conclusions: Lesions from the trunk submitted as BCC and presenting histopathologically as a lichenoid interface dermatitis are not always BLKs. Although no confident recommendations can be given on the basis of this limited study, deeper sections may be warranted if lesions are crusted and/or associated with only minimal vacuolar changes at the dermo-epidermal junction and no or few melanophages in the papillary dermis.

Background Autoimmune dermatitis, specifically interface dermatitis, is rarely reported in nonhuman primates. Results and Conclusions This report describes a case of idiopathic immune-mediated dermatitis clinically manifesting as palmoplantar hyperkeratosis in a rhesus macaque, successfully controlled with the use of long-term oral corticosteroid therapy.

Currently, one of the most common causes of skin biopsy in non-tumor pathology are skin reactions to drugs. These can manifest virtually as all known histopathological patterns.Adverse drug reaction (ADR) is defined by WHO as a response to a drug which is noxious and unexpected, which occurs at doses normally used in humans for prophylaxis, diagnosis, therapy of a disease or for modification of physiological function.We describe here the most frequent interface drug induced dermatitis and present three clinical cases.

Imiquimod (Aldara) is a topical immune response modifier effective against a variety of cutaneous tumors. Post therapy histologic reaction patterns have not been well characterized. Here, we present 2 patients treated with imiquimod, whose biopsies showed interface dermatitis of the epidermis and the adnexae with prominent periadnexal and perivascular lymphocytic inflammation. Without the clinical history, these histologic findings may be misinterpreted as lupus erythematosus. This report describes a new finding in imiquimod-treated skin and supports the diversity of reaction patterns that may be seen in association with imiquimod treatment.

Mechanic's hands is a poorly defined clinical finding that has been reported in a variety of rheumatologic diseases. Morphologic descriptions include hyperkeratosis on the sides of the digits that sometimes extends to the distal tips, diffuse palmar scale, and (more recently observed) linear discrete scaly papules in a similar lateral distribution. The association of mechanic's hands with dermatomyositis, although recognized, is still debatable. In this review, most studies have shown that mechanic's hands is commonly associated with dermatomyositis and displays histopathologic findings of interface dermatitis, colloid bodies, and interstitial mucin, which are consistent with a cutaneous connective tissue disease. A more specific definition of this entity would help to determine its usefulness in classifying and clinically identifying patients with dermatomyositis, with implications related to subsequent screening for associated comorbidities in this setting.

Background: Colloid bodies (CB) in direct immunofluorescence (DIF) studies are usually found in interface dermatitis. Furthermore, CB can be found in various skin diseases and even in normal skin. Aim: To evaluate the diagnostic value of CB deposits in DIF studies. Methods: From 1996-2007, data from 502 patients where DIF studies showed immunoreactants at CB were enrolled. The definite diagnoses of these patients were based on clinical, histopathological and immunofluorescent findings. The results of DIF studies were analyzed. Results: Immunoreactants at CB were detected in 44.4%, 43.8%, 4.2%, 3.8%, and 2.2% of interface dermatitis, vasculitis, autoimmune vesiculobullous disease, panniculitis, and scleroderma/morphea, respectively. The most common immunoreactant deposit of all diseases was Immunoglobulin M (IgM). Brighter intensity and higher quantity of CB was detected frequently in the group with interface dermatitis. Conclusions: Immunoreactant deposits at CB alone can be found in various diseases but a strong intensity and high quantity favor the diagnosis of interface dermatitis. CB plus dermoepidermal junction (DEJ) deposits are more common in interface dermatitis than any other disease. Between lichen planus (LP) and discoid lupus erythematosus (DLE), CB alone is more common in LP; whereas, CB plus DEJ and superficial blood vessel (SBV) is more common in DLE. The most common pattern in both diseases is CB plus DEJ. The quantity and intensity of CB in LP is higher than in DLE.

autoimmune disorder which affects many organ systems including the skin, joints and internal organs. Cutaneous lupus diseases can have a diverse clinical presentation but are unified by a specific histopathological pattern, namely, a lymphocytic interface dermatitis with prominent basilar keratinocyte death by apoptosis (Fig. 1). The skin can also be involved by other pathomechanisms such as the lupus vasculitis sometimes associated with systemic lupus erythematosus (SLE).

Background: The data on the histology of cutaneous lesions of drug reaction with eosinophilia and systemic symptoms (DRESS) is limited. Aims: To study the histopathology of cutaneous lesions of drug reaction with eosinophilia and systemic symptoms (DRESS) and to identify any features with diagnostic or prognostic significance. Methods: All patients admitted to the dermatology ward of government medical college, Kozhikode from January 1, 2014 to December 31, 2014 with probable or definite DRESS as per the RegiSCAR scoring system and who were willing to undergo skin biopsy were included in this prospective study. Results: The study population comprised of nine patients. The consistent histological finding documented was the predominantly lymphocytic dermal inflammatory infiltrate. Four of the five patients whose histology revealed focal interface dermatitis and keratinocyte vacuolation with or without apoptotic keratinocytes, had elevated liver transaminases. Tissue eosinophilia was associated with disease flares. The presence of atypical lymphocytes in peripheral smear and histological evidence of dense dermal inflammatory infiltrate showed an association with hepatic involvement. Limitations: The main limitations of our study were the small sample size and our inability to carry out a detailed immunohistochemistry work-up. Conclusions: In the appropriate setting, varying combinations of epidermal hyperplasia, spongiosis, parakeratosis and individually necrotic keratinocytes in the background of lymphocyte predominant dermal infiltrate (with some atypia) favor a diagnosis of drug reaction with eosinophilia and systemic symptoms. Female sex, the presence of atypical lymphocytes in peripheral smear, dense dermal inflammatory infiltrate, tissue eosinophilia and interface dermatitis with or without keratinocyte necrosis was associated with a poor prognosis.

Reflectance confocal microscopy (RCM) allows real-time, noninvasive microscopic view of the skin at nearly histologic resolution serially over time. RCM increases the sensibility and sensitivity of the diagnosis of skin tumours. RCM evaluates descriptive features of psoriasis, lupus erythematosus, contact dermatitis, and others. Three groups of optical histology have been described: psoriasiform, spongiotic, and interface dermatitis. In a multicenter study, RCM patterns of spongiotic, hyperkeratotic, and interface dermatitis have been analyzed and an algorithmic method of analysis for fast application in the clinical setting based on a multivariate analysis has been proposed. A tree decision diagram has been also established.

The diagnosis of melanocytic lesions can be challenging and immunohistochemical study is a valuable tool for dermatopathologists. We report two cases initially simulating melanoma in situ, reviewing the histopathological and immunohistochemical findings and the cases published in the literature with similar findings/results. We emphasize the importance of clinicopathological correlation in the evaluation of lesions with interface changes and in the "pseudomelanocytic nests", which may simulate melanoma in situ. We also highlight the importance of using a immunohistochemistry panel in addition to Melan-A, in the study of these lesions.