Lichen striatus

Association between the skin microbiome and lichen striatus hypopigmentation: Cutibacterium acnes as a potential cause

BACKGROUND

Lichen striatus (LS) is an acquired skin disorder with a linear pattern along Blaschko's lines. It commonly occurs in childhood, and the lesions spontaneously regress within several months.

OBJECTIVES

Although up to 50% of LS cases exhibit hypopigmentation that can persist for several months to years, it is unknown why LS is associated with such a high incidence of hypopigmentation compared to other inflammatory skin diseases. Therefore, this study aimed to analyse the differences in the skin microbiome between LS patients with and without hypopigmentation.

METHODS

Differences in skin microbiome were analysed using whole genome sequencing of skin biopsies and subsequent bioinformatics analyses.

RESULTS

Some microbes commonly found in hypopigmented skin disorders, including Cutibacterium acnes, were more abundant in patients with LS showing hypopigmentation than in those not showing hypopigmentation.

CONCLUSIONS

The skin microbiota may be involved in the development of hypopigmentation in LS and may be considered a treatment target to reduce LS duration and hypopigmentation.

Post-Inflammatory Hypopigmentation: Review of the Etiology, Clinical Manifestations, and Treatment Options

Post-inflammatory hypopigmentation is a common acquired pigmentary disorder that is more prominent in skin of color, leading to great cosmetic and psychosocial implications. Often, a diagnosis with a pigmentary disorder can negatively impact an individual's health-related quality of life and may result in stigma. Although most cases of post-inflammatory hypopigmentation resolve spontaneously over time, a systematic diagnostic approach can help with identifying the underlying etiology and informing treatment strategies. It can be due to cutaneous inflammation, sequelae of inflammatory or infectious dermatoses, or dermatologic procedures. Therefore, a thorough understanding of the epidemiology, patient history, physical exam findings, and clinical features of post-inflammatory hypopigmentation phenomenon can explain the primary cause to providers and allow for patient education. It is also important to understand the various therapeutic approaches available and the efficacy of these options, which will inform providers to choose the appropriate therapy for patients. Although algorithms exist for classifying acquired disorders of hypopigmentation, there are no established algorithms for the diagnosis and treatment of post-inflammatory hypopigmentation, which warrants further exploration and discourse.

Mosaicism in genodermatoses

Genodermatoses are inherited disorders presenting with cutaneous manifestations with or without the involvement of other systems. The majority of these disorders, particularly in cases that present with a cutaneous patterning, may be explained in the context of genetic mosaicism. Despite the barriers to the genetic analysis of mosaic disorders, next-generation sequencing has led to a substantial progress in understanding their pathogenesis, which has significant implications for the clinical management and genetic counseling. Advances in paired and deep sequencing technologies in particular have made the study of mosaic disorders more feasible. In this review, we provide an overview of genetic mosaicism as well as mosaic cutaneous disorders and the techniques required to study them.

Lichenoid and interface dermatoses

The terms 'lichenoid' and 'interface' dermatitis are often used interchangeably to describe an inflammatory pattern characterized histologically by damage to the basal keratinocytes in the epidermis. The mechanism of cell damage of such cells is now best understood as apoptosis, or programmed cell death. This inflammatory pattern of dermatoses, is also accompanied frequently by a band of lymphocytes and histiocytes in the superficial dermis, that often obscures the dermal-epidermal junction, hence the term 'lichenoid'. A discussion of the more common lichenoid/interface dermatitides encountered in the routine clinical practice encompasses the following entities: lichen planus, lupus erythematosus, dermatomyositis, erythema multiforme, graft versus host disease, fixed drug reactions, and multiple others.

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.

Bilateral Lichen Striatus

We describe a very rare case of bilateral lichen striatus on the lower extremities with a history of more than ten years. Histopathologically, the lesions demonstrated a lichenoid tissue reaction with foci of spongiosis and perivascular inflammatory cell infiltration. In addition, the finding of lymphocytic infiltrations around the eccrine duct was observed. They were treated successfully with topical application of corticosteroid ointment. To the best of our knowledge, no other lichen striatus case has been reported with bilateral distribution and such long-term persistence.

Facial lichen striatus in children: retracing the lines of Blaschko

We report seven patients with facial lichen striatus along the lines of Blaschko who presented to our pediatric dermatology unit between 2003 and 2009. The mean age of diagnosis was 4.6 years (range 2.5-9 years). Three of the cases were associated with atopic dermatitis, and one case presented with vitiligo. In the six patients for whom we have follow-up, all lesions resolved without pigmentary changes in an average of 11 months. This case series describes the distribution, presentation, and natural history of lichen striatus along facial lines of Blaschko. From our experience, clinical diagnosis and monitoring without biopsy is a reasonable approach to the management of uncomplicated lichen striatus, particularly when the face is involved.

Simultaneous lichen striatus in siblings along the same Blaschko line

Lichen striatus (LS) is an asymptomatic, spontaneously resolving linear dermatosis consisting of 2 to 4 mm flat topped papules following the lines of Blaschko. Two siblings presented with a simultaneous occurrence of LS along the same Blaschko line of the left upper extremity. Only four other cases of a simultaneous occurrence of LS in related siblings have been reported, but none of these have occurred in the same extremity. Although 10 years have passed since the last case report of this unique concurrent familial eruption, few discoveries have been made regarding its etiology. Several theories have been proposed including environmental agents, cutaneous injury, viral infection, hypersensitivity, and genetic predisposition. These theories are discussed along with retrotransposons, a possible new explanation for the pathogenesis of this and other Blaschko line disorders.

"Pediatric blaschkitis": expanding the spectrum of childhood acquired Blaschko-linear dermatoses

We describe two young children who developed relapsing, pruritic, papulovesicular eruptions in multiple bands along Blaschko lines on the neck, trunk, and extremities. Skin specimens in both revealed spongiotic dermatitis. This represents the first report of "blaschkitis" in children, providing further evidence that lichen striatus and blaschkitis are related acquired Blaschko-linear dermatoses that exist on a spectrum rather than as the childhood and adult form of a single disease entity. We highlight the features that differentiate blaschkitis from lichen striatus, review the potential roles of cutaneous mosaicism, environmental triggers, and background immunologic state in their pathogenesis, and discuss the spectrum of inflammatory dermatoses that can follow Blaschko lines.

Lichen striatus in an adult following trauma

A 36-year-old man presented with a linear erythematous eruption along his right forearm and dystrophy of his right thumbnail. These changes had developed 2 weeks after his right thumb had been pricked by a pineapple leaf and evolved over a 6-week period. Histopathology revealed features consistent with lichen striatus. He complained of mild intermittent pruritus, which responded to moderate-potency topical corticosteroids. At 12 months the skin eruption had improved, but the nail changes persisted.

Lichenoid eruptions in children

Lichenoid eruptions are quite common in children and can result from many different origins. In most instances the precise mechanism of disease is not known, although it is usually believed to be immunologic in nature. Certain disorders are common in children, whereas others more often affect the adult population. Lichen striatus, lichen nitidus, Gianotti-Crosti syndrome, and lichen spinulosus are examples of lichenoid lesions that are more common in children than adults. Distinguishing these diseases is necessary for prediction of the course of the eruption and for optimal management. In most cases, certain clinical characteristics enable the clinician to reach a diagnosis, whereas in other cases biopsy is required for a definitive answer. Many of these lesions are self-limited and only require symptomatic treatment, although corticosteroids can hasten resolution in certain disorders. Discontinuation of the medication is often sufficient for resolution of lichenoid drug eruptions.

Lichen striatus: description of 89 cases in children

Lichen striatus (LS) is a benign, self-limited, linear, inflammatory dermatosis of unknown etiology that usually affects children. We analyzed 89 cases in regard to age of appearance, sex, race, symptoms, seasonal incidence, localization of lesions and affected side of the body, and presence of atopy. Lesions predominated on the inferior limbs, with no preponderance of any age, and were asymptomatic in the majority of the instances. There was no difference in the incidence of LS in regard to the season of the year. A possible association of lichen sclerosus with atopy and pruritus was observed.

Lichen striatus: clinical and laboratory features of 115 children

To analyze the clinical features, response to treatment, and follow-up of lichen striatus and any associated symptoms or disease, we designed a retrospective study involving 115 affected children at the Pediatric Dermatology Unit of the Department of Dermatology of the University of Bologna, Bologna, Italy. Between January 1989 and January 2000 we diagnosed lichen striatus in 37 boys and 78 girls (mean age 4 years 5 months). We studied their family history and the season of onset, morphology, distribution, extent, duration, histopathology, and treatment of their lichen striatus. We found that family history was negative in all our patients except for two pairs of siblings. The majority of children had the disease in the cold seasons; precipitating factors were found in only five cases. The most frequently involved sites were the limbs, with no substantial difference between upper and lower limb involvement. When lichen striatus was located on the trunk and face, it always followed Blaschko lines; in seven children the bands on the limbs appeared to be along the axial lines of Sherrington. In 70 cases, lichen striatus was associated with atopy. The mean duration of the disease was 6 months and relapses were observed in five children, and in one instance the disease had a prolonged course. Only a few case study series of lichen striatus in children have been reported and ours is the largest to date. The etiology of lichen striatus remains unknown in the majority of our patients. The confirmed association with atopy observed in our patients may be a predisposing factor. It has generally been accepted that lichen striatus follows the lines of Blaschko, and this distribution is a sign of both a topographic and a pathogenetic concept. In patients where lichen striatus is along axial lines, a locus minoris resistentiae, we suppose that this distribution may only be an illusory phenomenon in instances in which the trigger factor prefers this route, consisting of several successive Blaschko lines, but appearing as a single band.

Facial lichen striatus: successful treatment with tacrolimus ointment

We report a 22-year-old Japanese woman with facial lichen striatus (LS). The distribution of the lesions corresponded to that of Blaschko's lines. Histology of the lesional skin showed an inflammatory cell infiltrate around hair follicles and eccrine glands. Treatment of the linear lesions with tacrolimus ointment once or twice daily resulted in a dramatical improvement in a short time. LS is a T-cell-mediated inflammatory disease and tacrolimus ointment may be an effective alternative treatment for this disease especially when the lesions are located on the face.

Incontinentia pigmenti: a review and update on the molecular basis of pathophysiology

Incontinentia pigmenti is an uncommon X-linked dominant disorder, lethal in the majority of affected males in utero and variably expressed in females. Cutaneous manifestations are classically subdivided into 4 stages: vesicular, verrucous, hyperpigmented, and atrophic. Various hair and nail abnormalities, dental anomalies, and ophthalmologic and neurologic deficits are associated with the disorder. The gene for incontinentia pigmenti has been mapped to Xq28. Recently, mutations in the NEMO/IKKgamma gene located at Xq28 have been found to cause expression of the disease. Knockout mice heterozygous for NEMO/IKKgamma gene deficiency develop a clinical phenotype very similar to that of incontinentia pigmenti. NEMO/IKKgamma is an essential component of the newly discovered nuclear factor kappaB (NF-kappaB) signaling pathway. When activated, NF-kappaB controls the expression of multiple genes, including cytokines and chemokines, and protects cells against apoptosis. The mechanism by which NEMO/IKKgamma deficiency causes, via the NF-kappaB pathway, the phenotypical expression of the disease has recently been elucidated. In addition, the newest research findings on eosinophil recruitment through eotaxin release by activated keratinocytes are described in the review. Finally, anhidrotic ectodermal dysplasia with immunodeficiency, a disorder allelic to incontinentia pigmenti, is discussed together with implications on the current understanding of NF-kappaB function. (J Am Acad Dermatol 2002;47:169-87.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants will have a comprehensive and current understanding of incontinentia pigmenti, including its typical and uncommon clinical and histopathologic characteristics, diagnostic assessment, and current management strategies. Additionally, participants will gain the most current knowledge of the genetic and molecular basis of cutaneous pathomechanism.

Inflammatory linear verrucous epidermal naevi: a review of 23 cases

Twenty-three patients diagnosed with inflammatory linear verrucous epidermal naevi (ILVEN) over a 13 year period are reviewed retrospectively. These ILVEN showed a predilection for the buttock and legs and were usually unilateral. Onset of the lesions was usually within the first 6 months of life and extension beyond the original margins occurred in 26% of cases. Sixteen of the 23 patients were male. Ten patients had ILVEN predominantly involving the left side, 12 were on the right side and, in one case, the side involved was not recorded.

Lichen striatus. Histological, immunohistochemical, and ultrastructural study of 37 cases

BACKGROUND

Lichen striatus (LS) is a papulosquamous disorder with a distinctive linear distribution. The linearity has been shown to correspond in many cases to the pattern of Blaschko's lines. The etiology is unknown. LS can usually be identified by clinical history and histology of typical lesions. However, the histologic features are diverse and some have stated they are nonspecific.

METHODS

In an effort to identify those characteristic features, we have reviewed the routine slides in 37 cases for their diagnostic criteria. Ten cases were studied further by immunohistochemistry.

RESULTS

The patient's ages ranged from 1.3 to 49 years with mean age of 17.5 years. A female-to-male ratio was 1.6 to 1. The lesions were predominantly distributed on the extremities in 26/34 cases. The consistent histologic features were: hyperkeratosis (29/37), parakeratosis (21/37) with a few necrotic keratinocytes (28/37) in the epidermis, mild spongiosis (29/37) with exocytosis of lymphocytes (33/37). The dermal infiltrate comprised mainly lymphocytes and macrophages. At the dermal-epidermal junction, the infiltrate was either focal (20/37) or lichenoid (17/37) patterns. Superficial and deep perivascular lymphocytic inflammatory infiltrate was present in most of the cases (33/37). Appendageal involvement (34/37) was in hair follicles (24/37) or eccrine glands or ducts (22/37) or both (12/37). Satellite cell necrosis may be seen (11/37). Colloid bodies were present in 16/37 of the cases. Immunohistochemistry showed that most of the small lymphocytes in the upper dermis and epidermis were positive for CD7. Most of the lymphocytes in the epidermis were positive for CD8. CD1a Langerhans' cells were either decreased (5/10) or increased (3/10) or normal (2/10) in the epidermis.

CONCLUSION

The histologic diagnosis of LS can be made on the basis of the combination of these histologic features in the appropriate clinical context. Multiple biopsies may be necessary to determine whether all of these features are present in a given case.

Linear eruptions of the nose in childhood: a form of lichen striatus?

We report four children with linear eruptions on the nose, with overlapping features of lichen striatus and linear cutaneous lupus erythematosus. However, linear lupus erythematosus has rarely been reported, and lichen striatus, although classically linear, rarely affects the face. The linear distribution of lesions from the glabella to the ala nasi may represent distribution following Blaschko's lines.

Self, intentionality, and immunological explanation

In this paper I propose that there are a number of conceptual reasons to preserve self-concepts in immunology. First, I contend that immunological language, including self-terminology, is neither genuinely anthropomorphic, nor perniciously teleological. Furthermore, although teleology associated with future-directed purposive intent is clearly inappropriate in biological contexts, a special type of teleology, intentionality-as-aboutness, needs to be present if there is to be functional explanation in immunology. Second, based on an analogy with the human self, a self comprised of both non-specific innate functions and somatic self-representation, I claim that self-terminology is very appropriate in immunological contexts. Finally, given the appropriateness of self-concepts in immunology, I suggest that the most satisfactory conceptual structure for self-nonself discrimination probably includes both innate and somatic mechanisms.

Bart syndrome: the congenital localized absence of skin may follow the lines of Blaschko. Report of six cases

Three cutaneous manifestations are characteristic of Bart syndrome: congenital localized absence of skin (CLAS), mucocutaneous blistering, and nail abnormalities. Six cases of Bart syndrome are herein reported. Localized absence of skin is present at birth, particularly on the anterior aspects of the lower extremities and dorsa of the feet. Physical trauma in utero has been proposed as a mechanism to explain the denuded areas on the limbs. The recurrent, highly similar pattern of the congenital defect in regard to location and clinical appearance in our patients and in most of the reported cases strongly suggests that trauma is too simplistic an explanation. Because of the observed bilateral and symmetric distribution of denuded areas in an S-shaped broad band, their sharply demarcated borders, the involvement of the toe webs, and the frequent similar involvement of the soles, we suggest that congenital localized absence of skin in Bart syndrome may follow the lines of Blaschko.

Linear childhood discoid lupus erythematosus following the lines of Blaschko: a case report with review of the linear manifestations of lupus erythematosus

Seventeen cases of childhood discoid lupus erythematosus (DLE) have been previously reported in the literature. We describe the first reported case of childhood linear DLE following the lines of Blaschko. The clinical and histologic characteristics of childhood DLE are discussed and a review of the linear manifestations of childhood LE is presented.

Simultaneous occurrence of lichen striatus in siblings

Lichen striatus (LS) is a self-limiting linear papular dermatosis of unknown etiology seen mostly in children. We report LS occurring in two pairs of siblings: two sisters who had LS at an interval of 6 months and a brother and sister who had the dermatosis contemporaneously after an episode of flulike fever. In all four patients family history was positive for atopy. LS is frequently associated with atopic diseases. The abnormal immune status of patients with atopy may be a predisposing factor in the induction of LS. In our patients the simultaneous occurrence of LS in siblings after a flulike fever appears to corroborate the hypothesis that a viral infection is a possible candidate, as other authors have proposed. The rarity of familial cases of LS is, in our opinion, due to the exceptional confluence of difference sporadic events (atopy, viral infection caught at a specific period of life such as childhood, and a genetic predisposition) simultaneously present in the same patient.

Lichen striatus: simultaneous occurrence in two nonrelated siblings

Lichen striatus is an uncommon, self-limited eruption of unknown etiology. What role genetic or environmental influences play in its pathogenesis is unclear. We report two nonrelated, adopted children living in the same household who simultaneously developed lichen striatus.