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Hypomelanosis of Ito is a rare heterogeneous neurocutaneous disorder often associated with central nervous and musculoskeletal system involvement. Herein, we report the first case of hypomelanosis of Ito in the literature presenting with unilateral dilation of Virchow-Robin spaces (VRS). A girl aged 16 years old presented with a 1-year history of headache. Her physical and neurological examinations were normal, except for the presence of unilateral cutaneous macular hypopigmented whorls and streaks on lower side of the right trunk and lower limb, termed as Blaschko's lines. She had mild deficits in cognitive and adaptive functioning. Hearing, renal, dental, ophthalmologic, metabolic, and cardiac assessments were normal. Brain magnetic resonance imaging (MRI) showed markedly unilateral hemispheric enlarged VRS without contrast enhancement and diffusion restriction. To the best of our knowledge, our case is the first report describing the unilateral hemispheric enlarged VRS in a patient with hypomelanosis of Ito. Our report suggested that hypomelanosis of Ito may have unilateral dilation of VRS in brain MRI.

Linear hyperpigmentation is an unusual anatomical configuration in clinical dermatology. Owing to its rarity, consensus on the most effective method of classification is lacking. While linear hyperpigmentation generally follows Blaschko’s lines, this is not universal. Clinical findings such as adherence to Blaschko’s lines, associated morphological findings (including other cutaneous lesions), and systemic manifestations can be used to further characterize and diagnose variants of the disorder. Early detection of any underlying disease is vital, especially in cases with effective management, because the disorder may make it difficult to manage hyperpigmentation. Herein, we introduce a logical clinical diagnostic approach that represents a useful tool for dermatologists to efficiently evaluate patients presenting with linear hyperpigmentation. A simplified systematic and evidence-based approach is useful for this clinical condition owing to the heterogeneous causes and lack of specific diagnostic tools.

Background Spontaneous atrophic scarring is characterised by an idiopathic, non-inflammatory macular atrophy that typically occurs on the face and presents as shallow atrophic scars having sharp margins and may be linear, rectangular or varioliform. Aim To describe the cases of spontaneous atrophic scarring over perioral region of face having specific feline band pattern in a retrospective study. Materials and methods All patients with facial atrophoderma (perioral region) were evaluated clinically and histopathologically in tertiary care centres over 3 years. Patients with facial atrophoderma but no perioral involvement and secondary atrophoderma were excluded from the study. Patients were evaluated for number, sites, size and shape of lesions and were confirmed histopathologically. Results There were 14 patients (10 females) with facial atrophoderma particularly over the perioral region. Three patients had perioral involvement with a few lesions on the cheeks and forehead. All patients developed atrophoderma spontaneously without preceding inflammation. Most of the patients were asymptomatic except for mild pain or burning at the time of development of atrophic lesions; however, none of the patients were symptomatic at the time of presentation. Histopathology in 5 patients showed epidermal and upper dermal atrophy with no/minimal signs of inflammation. Conclusion Idiopathic atrophodermas over the face can be due to spontaneous atrophia maculosa varioliformis cutis or atrophoderma of Moulin.

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Basaloid follicular hamartoma (BFH) is a rare follicular malformation characterized by variable clinical presentations and identical histopathologic features. We present the cases of a 3-month-old boy and an 8-year-old boy with linear unilateral BFH. To the best of our knowledge, only 14 cases of linear unilateral BFH have been described in the English-language literature.

Linear Atrophoderma of Moulin (LAM) is characterized byacquired unilateral hyperpigmented depressed band like skinlesions following blaschko’s lines. Moulin et al.1first definedthe condition in 1992 and, later, Baumann et al.2reportedsimilar features on a patient and named the condition asLAM.In our 2 case reports, we described first a 26-year-old femalewith asymptomatic hyperpigmented lesions since one year.On physical examination, there was a depressed band-likelesion on the right side of chin along the neck followingblaschko’s lines (Figure 1A).

Lichen striatus (LS) is an uncommon, acquired, self-limited, and benign linear dermatosis of unknown etiology that most often occurs unilaterally and is confined to the lines of Blaschko. A healthy 7-year-old girl presented to our clinic with bilateral asymmetric LS occurring on the right arm and left leg of 1-year duration. Very few cases of bilateral LS have been previously reported in the literature, with none from clinics within the United States. The etiology of LS is currently unknown; however its confinement to Blaschko’s lines, which represent embryologic migration of skin cell clones, does provide insight into a possible pathogenesis. It seems most likely that an individual’s development of LS is linked to their genetic predisposition and a subsequent triggering event. Our case serves as a strong example of a rare presentation of LS and facilitates discussion of the clinical diagnostic process and possible pathogenesis of this dermatosis.

The patched tumor suppressor gene (PTCH1) encodes a receptor, which is a key component of the hedgehog signalling pathway. Mutations in PTCH1 are implicated in the development of sporadic basal cell carcinomas (BCC), as well as those in Gorlin Syndrome. Rarely, BCCs may develop in a linear pattern along lines of Blaschko due to cutaneous mosaicism. In cases in which there are other features of Gorlin syndrome, genomic analysis has demonstrated lesional mutations in the Hedgehog signalling pathway. Causative mutations, however, have not been firmly demonstrated in the cases of linear and segmental BCCs in otherwise healthy individuals. Herein, we report a case of a 31 year-old Caucasian woman with linear development of multiple superficial BCCs in a Blaschkoid distribution without other characteristic findings of Gorlin syndrome. Genomic analysis of lesional skin by whole-exome sequencing identified a novel heterozygous mutation PTCH1: NM_000264.3, Exon 15, c.2336-2337insGGTAGGA, p.Asp779Glufs*13 in PTCH1, shared by two discrete samples within the lesion, while no mutations were found in the non-lesional skin or peripheral blood. Given the young age of our patient and linear distribution of BCCs on non-sun exposed skin, our findings suggest segmental mosaicism. The patient was treated with topical 5% imiquimod with histologically confirmed clearance of BCCs in 2 months.

Background: The pattern of distribution of skin diseases remains one of the most elusive problems in dermatology, particularly when multiple pathologies are involved and coexistence of patterns is present. Most skin diseases show a predilection for certain body areas and are located in characteristic patterns. Many dermatoses exhibit lesions in a segmental fashion concomitantly with disseminated patterns. Sometimes the sites of predilection are inexplicable. Objectives: The main purpose of this paper is to give an overview on the peculiar arrangement of cutaneous lesions in both congenital and acquired skin disorders as well as reactive phenomena in vulnerable areas, in order to better recognise them clinically and understand their pathogenesis. Methods: Based on personal observations and a review of literature, this paper summarises the basics in understanding the patterned distribution of skin lesions, highlights the significance of the lines of Blaschko and their relationship with mosaicism, and describes some of the reactive skin phenomena. Results: Skin mosaicism plays a crucial role in the distribution and arrangement of skin lesions, as demonstrated by recent advances in genetic research in an increasing number of various skin diseases.

Lupus panniculitis of the scalp (LPS) is a rare and distinctive clinical feature of lupus erythematosus panniculitis (LEP) with linear alopecia along Blaschko's lines. In this study, we investigated clinical features and treatments of LPS by literature review of articles in the English language from PubMed and SCOPUS databases up to April 2018. The following key words, "lupus panniculitis, "lupus erythematosus panniculitis", "lupus profundus", "head", and "scalp", were used. Twenty cases of LPS were identified (mean age = 26.4 [10-53] years, female: male ratio = 1:1, mean disease duration = 86.89 [8-336] weeks). The most commonly affected areas of scalp included parietal (70%), frontal (45%), temporal (40%), occipital (30%), and vertex (10%), along 70% of Blaschko's lines with morphologic lesions linear, annular, arch-shaped, and ulcer. Besides, ANA (60%) was in particular noted. Hydroxychloroquine, oral prednisolone, intralesional corticosteroid, and methotrexate were the most common treatments, with complete response after an average period of 8.08 (2-12) weeks. Systemic lupus erythematosus (SLE) was developed in four cases (20%) during follow-up, with high recurrence of 35%. We reported distinctive and rare cases of LPS.The continuing follow-up was highly recommended to avoid probable recurrence and SLE development.

Background: Pathogenic mechanism that determines the localization of vitiligo patches and thus a patterned distribution in patients with nonsegmental vitiligo has remained poorly elucidated. A distributional similarity of the vitiligo patches with Blaschko's lines has been documented in patients with segmental vitiligo, both isolated segmental vitiligo and mixed vitiligo but never in cases of nonsegmental vitiligo. Methods: Distribution of nonsegmental vitiligo patches on face and neck regions was assessed and compared with Blaschko's lines and also with embryonic pigmentary segments on the face. Results: This study has documented distributional similarity of the nonsegmental vitiligo patches on face and neck with Blaschko's lines and the “embryonic pigmentary segments” among 154 (58.6%) cases. Patches around the palpebral and other fissures like periorbital, perinasal, perioral, and periaural were more common. In addition to the vitiligo patches, the spared areas were also found to respect the embryonic segmental outlines and follow the Blaschko's lines. Conclusion: Distributional pattern of the individual nonsegmental vitiligo patches along the Blaschko's lines and embryonic pigmentary segments suggests that mosaicism might control the susceptibility to the disease process in a patterned manner. Limitation: No genetic testing could be performed to confirm the hypothesis. Evaluation of nonsegmental vitiligo was done only on the face and neck areas.

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.

Linear dermatoses are unusual entities whose distribution reflects cutaneous mosaicism, even when they occur in adult life. Adult blaschkitis (AB) and lichen striatus (LS) always follow this peculiar distribution. Although usually referred to as distinct entities, the clinical and histopathological presentation of lichen striatus in adults may be similar to those of adult blaschkitis. Moreover, some cases with overlapping features between lichen striatus and linear lichen planus have been published, making precise diagnosis very difficult. Recently, the concept of a wide spectrum of blaschkolinear dermatoses with AB and LS located somewhere within it has been proposed but it has not gained general recognition. We report three cases of dermatoses following the lines of Blaschko in adults (two women and one male, ages 35, 50 and 56, respectively). They involved the upper extremity in two cases and the lower in the third. Clinically, they were interpreted as linear lichen planus or blaschkitis but, histopathologically, they showed features consistent with lichen striatus. Lesions subsided with topic steroids and/or tacrolimus ointment, they are an example of the significant overlapping between these three entities, demonstrating that they may exist on a spectrum both clinically and histopathologically and clinico-pathologic correlation is essential to achieve an accurate final diagnosis. A detailed review of previously published cases has also been made.

This case presents an unusual manifestation of cutaneous chronic graft-vs-host disease (cGVHD) mimicking psoriasis along Blaschko's lines. Such a presentation may pose a particular challenge to providers as it is quite rarely reported, and, therefore, it is possibly misdiagnosed. cGVHD may mimic psoriasis and should be considered in any patient previously transplanted even with a previous history of psoriasis. A Blaschkoid pattern of cGVHD is unusual and may be the manifestation of an immune reaction unveiling a previously masked mosaicism.

Darier disease (DD) is an autosomal dominant genodermatosis characterized by multiple keratotic and crusted papules over seborrheic areas, along with a variable involvement of oral mucosa, palmoplantar region, and nails. Segmental subtypes (type 1 and 2) are uncommon clinically limited forms of DD that usually present at middle age with few cutaneous lesions following Blaschko´s lines. We report a case of extensive multi segmental DD type 1 that developed in an elderly man, an unusual clinical onset of DD that dermatologists should bear in mind.

Lichen planus (LP) is a chronic inflammatory disorder that most commonly affects middle-aged individuals. LP involves the skin and/or mucous membranes, including oral, vulvovaginal, esophageal, laryngeal, and conjunctival mucosa. Linear LP, a rare distinct variant of LP, is characterised by pruritic eruption of lichenoid and violaceous papules in a linear distribution. We report an unusual presentation of linear LP in a 14-year-old child that extended from the left anterior nares to upper lip and into the oral mucosa up to the upper gum margin.

A 32-year-old Taiwanese man presented to our clinic with a 6-month history of linear hair loss in a wavy and curved pattern across the parietal and occipital scalp, resembling the distribution of Blaschko's lines. Physical examination showed interfollicular erythema and follicular plugging without skin atrophy or sclerotic change. Histopathology revealed a lymphoplasmacytic infiltrate in the perifollicular dermis and subcutis with abundant mucin deposition, consistent with the diagnosis of lupus panniculitis. Treatment with hydroxychloroquine and local steroid injection resulted in complete hair regrowth but recurrence was noted. Linear lupus panniculitis of the scalp presenting as alopecia along Blaschko's lines had so far been reported exclusively in five East Asians. Apart from classical lupus panniculitis, it had distinct clinical and histopathological features such as younger age of onset, male predominance, reversible clinical course without scarring, fewer associations with systemic lupus erythematosus, exclusive involvement of scalp, sparse inflammatory infiltration, abundant mucin deposition, higher degree of hyaline fat degeneration and negative results of immunofluorescent studies. Therefore, we propose linear lupus panniculitis of the scalp to be a distinct variant of lupus panniculitis and should be included in the differential diagnosis for focal or linear alopecia, especially in East Asians.

The aim of this study is to objectively evaluate whether linear scleroderma (LS) follows Blaschko’s lines (BL) in Korean patients using digital image processing. Thirty-two patients with LS were examined. According to the patients’ clinical photographs, their skin lesions were plotted on the head and body charts. With the aid of graphics software, a digital image was produced that included an overlay of all the individual lesions and was used to compare the graphics with the published BL. To investigate the image similarity between the graphic patterns of the LS and BL, each case was analyzed by means of Hough transformations and Czekanowski’s methods. The comparative investigation of the graphic similarity of distributional patterns between the LS and BL showed that Czekanowski’s similarity index was 0.947 on average. In conclusion, our objective results suggest that the graphic patterns of the distribution of the LS skin lesions showed a high degree of similarity and in fact were almost identical to that of BL which may be the lines of embryonic development of the skin. This finding may suggest that some developmental factors during the embryological age could constitute the cause of LS.

Background: The objective of the study was to study the incidence, age and sex distribution, association, distribution, clinical presentation, histopathological correlation of linear dermatoses at the skin Outpatient Department.Methods: A prospective study was conducted over a period of 1 year in 90 patients, attending the Department of Dermatology, at a tertiary care hospital, Chennai. Data collection, clinical examination and skin biopsy were recorded and analyzed statistically. Inclusion criteria were all patient with linear dermatoses. Exclusion criteria were Koebner phenomenon.Results: The incidence of linear dermatoses in our outpatient department- 0.2% per year. Among the linear dermatoses, lichen striatus was found to be the most common. The other dermatoses following Blaschko’s lines, in the descending order of frequency seen in this study were linear epidermal nevus, linear lichen planus, linear morphoea, inflammatory linear verrucous epidermal nevus, segmental vitiligo, hypomelanosis of ito, linear lichenoid dermatitis, linear psoriasis, segmental neurofibromatosis, linear whorled nevoid hypermelanosis, incontinentia pigmenti, nevus depigmentosus, linear porokeratosis. Female preponderance was noted. Majority of patients showed unilateral distribution mostly on the extremities.Conclusions: Most of the linear lesions are arranged along Blaschko’s line. The importance of histopathological correlation is obvious. Cases which were clinically diagnosed as lichen striatus, showed histopathological features of psoriasis and linear epidermal verrucous nevus. One case diagnosed clinically as epidermal nevus was found to be super imposed by psoriasis histologically. Another case clinically diagnosed as linear psoriasis clinically, was found to be linear porokeratosis on histopathology. Very few associations were noted.

Linear epidermal nevus (LEN) is a sporadic hamartomatous lesion of the skin due to the proliferation of clones of embryonic ectodermal cells, which are arranged according to a typical linear configuration known as Blaschko's lines. Oral involvement of LEN is very rare and few cases have been reported in the medical literature. We report two new cases of LEN with exclusive oral involvement, which presented with the typical unilateral or midline distribution. Oral LEN presents as an exophytic lesion with well defined borders and a verrucous or papillary surface which correspond, histologically, to epithelial papillomatosis with a moderate degree of hyperkeratosis and acanthosis. Oral LEN appears mainly at birth, grows slowly during childhood and stabilize by adolescence. Localized lesions do not show any recurrence after surgical removal but widespread lesions seem to have more risk of recurrence and are more difficult to manage. Functional problems and malignant transformation have not been reported.

Clinical findings in vitiligo challenge the widely accepted organ specific autoimmune pathomechanisms. We draw the attention to the fact that the distribution of segmental vitiligo (SV) fits in at least a subset of patients a pattern usually associated with cutaneous mosaicism. The association of SV to non-segmental vitiligo (NSV) now confirmed by several observations indicates a continuum between the two subsets with shared predisposing genetic factors, including genes operating specifically in the skin. Some pedigrees associating SV and NSV further suggest a mechanism of loss of heterozygosity for a dominant gene controlling part of the cutaneous phenotype. The mosaic hypothesis applies only to SV and to the rare SV-NSV association, but suggests that predisposing genetic factors in common NSV should also be searched directly in the skin. SV would be a good candidate disease to explore as a proof of principle of a new gene discovery strategy useful for multigenic disorders with organ specificity, applicable in priority to chronic inflammatory skin disorders.

Summary Background The aetiology of morphoea (or localized scleroderma) remains unknown. It has previously been suggested that lesions of linear morphoea may follow Blaschko’s lines and thus reflect an embryological development. However, the distribution of linear morphoea has never been accurately evaluated. Objectives We aimed to identify common patterns of clinical presentation in children with linear morphoea and to establish whether linear morphoea follows the lines of Blaschko. Methods A retrospective chart review of 65 children with linear morphoea was performed. According to clinical photographs the skin lesions of these patients were plotted on to standardized head and body charts. With the aid of Adobe Illustrator a final figure was produced including an overlay of all individual lesions which was used for comparison with the published lines of Blaschko. Results Thirty-four (53%) patients had the en coup de sabre subtype, 27 (41%) presented with linear morphoea on the trunk and/or limbs and four (6%) children had a combination of the two. In 55 (85%) children the skin lesions were confined to one side of the body, showing no preference for either left or right side. On comparing the overlays of all body and head lesions with the original lines of Blaschko there was an excellent correlation. Conclusions Our data indicate that linear morphoea follows the lines of Blaschko. We hypothesize that in patients with linear morphoea susceptible cells are present in a mosaic state and that exposure to some trigger factor may result in the development of this condition.

SUMMARY 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.

Segmental neurofibromatosis type 1 (NF-1) has the characteristic features of generalized NF-1 but is isolated to a particular segment of the body. Segmental NF-1 results from a postzygotic mutation during embryogenesis in the NF-1 gene on chromosome 17. The embryologic timing of the mutation and cell types affected predict the clinical phenotype. We present a case of a 52-year-old woman with segmental neurofibromas isolated to the right cheek and neck. We review the recent literature on the genetic and cellular differences between the various clinical manifestations of segmental NF-1. A MEDLINE search for cases of segmental neurofibromatosis was conducted. In patients with segmental NF-1 presenting as neurofibromas-only, the distribution follows a neural distribution in dermatomes because the genetic mutation appears to be limited to Schwann cells. In patients with pigmentary changes only, the NF-1 mutation has been shown to occur in fibroblasts and the distribution tends to follow the lines of Blaschko. Our patient’s neurofibromas were secondary to a postzygotic mutation in the NF-1 gene of neural crest–derived cells. This mutation most likely occurred later in embryogenesis in cells that had already differentiated to Schwann cells and were committed to the dermatomal distribution of the right neck and cheek region (C2).

36歳，男性。生下時より，右腹部に脱色素斑を認めていた。18歳の頃より脱色素斑が拡大し，右腹部を中心にBlaschko線に沿って帯状に分布するようになったため，当科を受診した。脱色素斑上には毛孔一致性丘疹がみられた。脱色素斑を含めた丘疹部の病理組織学的所見では，表皮基底層の一部でメラニン色素の減少がみられた。真皮では成熟した脂腺，アポクリン腺の増生がみられた。液状変性はなく，真皮上層に組織学的色素失調はみられなかった。以上の所見より脱色素斑に合併した脂腺母斑と診断した。過去に先天性の脱色素斑に脂腺母斑が合併した例やBlaschko線に沿ってみられる脂腺母斑の報告はなく，自験例は特異な臨床像を呈した症例と考えられた。

Epidermal naevi are localized malformations of the epidermis consisting of verrucoid scaly papules and plaques following Blaschko's lines. Genetic mosaicism has been proposed to underlie the development of linear epidermal naevi. Rarely, epidermal naevi show acantholytic histology similar to Darier's disease, a dominantly inherited skin condition characterized by widespread warty papules. As patients with acantholytic dyskeratotic naevi often give a history of worsening after sun exposure and the lesions are typical of Darier's disease, numerous authors have proposed that these patients have segmental Darier's disease. The postulated relationship has not been proven, however. Recently, we identified ATP2A2, which encodes the sarco/endoplasmic reticulum Ca(2+) ATPase isoform 2 as the defective gene in Darier's disease. In this report, we investigated the involvement of ATP2A2 in acantholytic dyskeratotic naevi following Blaschko's lines in two patients. We identified a nonsense mutation (Y894X) in the first patient and a nonconservative glycine to arginine mutation at codon 769 (G769R) in the other patient. These mutations were present in affected skin, and were not detected in unaffected skin or in leukocytes. We conclude that acantholytic dyskeratotic naevi can arise from a somatic mutation in ATP2A2. These individuals are mosaics for the mutation, but the risk of transmission of generalized Darier's disease will depend on whether the germline is affected. Our findings provide further evidence that Blaschko's lines do reflect genetic mosaicism and that the term acantholytic dyskeratotic naevus might be replaced in the future by segmental Darier's disease induced by postzygotic mosaicism. J Invest Dermatol 115:1144-1147 2000

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.

The lines of Blaschko represent one of the cutaneous patterns of mosaicism followed by various skin disorders. Developmental abnormalities affecting other tissues derived from the embryonic ectoderm and mesoderm are occasionally associated. We describe a 30-year-old man with depigmented, bilateral hypertrichosis and dilated follicular orifices following Blaschko’s lines associated with cerebral and ocular malformations. The findings suggest a previously unreported neurocutaneous, autosomal lethal gene syndrome from the group of epidermal naevus syndromes.

Hypomelanosis of Ito, also known as incontinentia pigmenti achromians, is a cutaneous condition characterized by various patterns of bilateral or unilateral hypopigmentation following the lines of Blaschko. It is a disorder of mosaicism, but may have genetic susceptibility factors. The skin findings can be accompanied by a central nervous system, ocular, and musculoskeletal defects. It affects both genders equally.

An ultrastructural study on two new cases of Ito's hypomelanosis is reported. According with previous studies on this pathological condition, a marked reduction of melanocytes is detected in the hypopigmented areas. In the proximity of preserved melanocytes, a nearly normal content of melanosomes is detected in basal keratinocytes. Melanocyte profiles are frequently located in close relationship with the basal lamina. An apparent increase of nerve endings is demonstrated at the dermo-epidermal edge. Nerve fibres show no pathological alterations. A functional impairement of the melanocytes is hypothesized, involving regressive changes and a tendence towards a round shape of their profiles. This could in part account for the prevalent basal location of the melanocytes. The role of the dermal nerve endings in the pathogenesis of the hypopigmented lesions is discussed.

We have previously shown that frontoparietal scleroderma en coup de sabre, a type of linear scleroderma that affects the face and scalp, follows the lines of Blaschko, but the question whether linear scleroderma that occurs in the limbs follows Blaschko's lines has not been answered. We describe the case of a 4-year-old girl with multiple morphea showing remarkable unilateral systematized distribution and whose linear lesions in the limbs appeared to follow Blaschko's lines. We suggest that linear scleroderma of the limbs, as well as frontoparietal scleroderma, may occur along the lines of Blaschko. Since both the unilateral distribution and the lesions along Blaschko's lines are the patterns created by genetic mosaicism, we suggest that a significant part of linear scleroderma and perhaps a smaller part of multiple morphea could be related to cutaneous mosaicism.

Background: Linear atrophoderma of Moulin (LAM) is a rare clinical entity which was first described by Moulin et al. in 1992. The diagnosis is clinical, characterized by acquired unilateral hyperpigmented, depressed band-like skin lesions following Blaschko's lines. The disease typically affects children or adolescents and has a good prognosis without evidence of long-term progression. To date, the pathophysiology is unclear. Different authors hypothesize that the disease is secondary to a mosaic manifestation as a result of a post-zygotic mutational event. Observations: Four patients (2 men, 2 women) had a history of unilateral band-like skin lesions located on the lower legs (50%) or the trunk (50%). Physical examination showed atrophic and hyperpigmented skin lesions along Blaschko's lines, which appeared during childhood in 3 cases and at the age of 20 in the last case. Lesions had progressed rapidly but seemed to have stabilized so far except for 1 case who presented spontaneous improvement. Histopathological examination revealed a normal epidermis with a hyperpigmented basal layer and a perivascular lymphocytic infiltrate in the dermis. Conclusion: LAM is a rare disease with 32 reported cases and remains an exclusion diagnosis. Since the problem is mainly esthetic, treatments should not be too aggressive.

Background: Aplasia cutis congenita (ACC) is a congenital absence of skin, and a single alopecic lesion on the scalp is the most common form. Main observation: We present a case of ACC with tetralogy of Fallot-A. Differetial diagnosis included Adams-Oliver syndrome and nevus psiloliparus. Interestingly, our patient showed multiple ACC lesions, which were located along Blaschko’s lines. Conclusions: As far as we know, our case is the third case of ACC with tetralogy of Fallot-A. Also, this is the first case of ACC associated with Blaschko’s lines. ( J Dermatol Case Rep. 2012; 6(2): 40-42)

Background: Basaloid follicular hamartomas (BFHs) may occur as single isolated tumors, as localized tumors or as multiple tumors in a disseminated or in a patterned distribution. Non-hereditary multiple and mostly unilateral basaloid follicular hamartomas arranged according to Blaschko`s lines with associated extracutaneous malformations have been designated as a genetic mosaicism disease and one entity. The transition of BFH into basal cell carcinoma as well as the formation of concurrent extracutaneous malignancies has been published. Methods: We present a case of multiple and unilateral basaloid follicular hamartomas arranged according to Blaschko`s lines in multiple and anatomically separated skin areas but lacking extracutaneous malformations. Its clinical features are compared to published cases and discussed on the basis of recent findings in embryology. Results: We would propose the hypothesis that in multiple and unilateral BFHs with or without extracutaneous symptoms, the affected cell clone arises shortly before or during gastrulation and comprises only a small fraction of cells of the epiblast. The mutated cells are then displaced and mixed with normal cells by a collective whorl-like migration of epiblast cells as it has been observed by life-microscopy in chicken embryogenesis. This could explain the predominantly unilateral distribution of BFHs in Blaschko`s lines as well as the dispersal of mutated cells along the anterior-posterior axis. Conclusions: The proposed mechanism leading to multiple and mostly unilateral BFHs in Blaschko`s lines with or without extracutaneous symptoms might serve as a blueprint for other mosaicizm diseases with cutaneous symptoms and facultative extracutaneous malformations.