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

A Case of Linear Exacerbation of Atopic Dermatitis with Secondary Prurigo Nodularis

Inflammatory acquired Blaschko-linear dermatoses (IABLD) are a continuous concept involving diseases such as lichen striatus, blaschkitis, and atopic dermatitis. However, atopic dermatitis that showed increase in severity along Blaschko lines is rarely reported on its own. Herein, we report a rare case of atopic dermatitis with secondary prurigo nodularis along Blaschko lines, which may be valuable in broadening the concept of IABLD. A 28-year-old male presented with multiple, pruritic, brownish nodules on the left lower extremity along Blaschko lines for 3 to 4 years. The patient had atopic dermatitis since childhood. Histopathologic findings revealed compact orthohyperkeratosis, hypergranulosis, spongiosis, and irregular acanthosis in the epidermis. Fibrosis with vertically arranged collagen fibers and perivascular lymphohistiocytic infiltration were shown in the upper dermis. We diagnosed the case as secondary prurigo nodularis along Blaschko lines, accompanied by the preceding atopic dermatitis. We hypothesized that the patient’s underlying atopic dermatitis increased in severity along Blaschko lines, and prurigo nodularis occurred due to frequent scratching. The lesions improved with topical methylprednisolone cream, oral antihistamines and intralesional triamcinolone injection.

Blaschkolinear Acquired Inflammatory Skin Eruption (BLAISE): Case Report of a Young Man Whose Dermatosis had Features of Lichen Striatus and Blaschkitis

Cutaneous conditions can follow Blaschko’s lines on the skin, which are thought to reflect patterns of cell migration and clonal expansion during embryonic development of the epidermis. These diseases are hypothesized to be caused by genetic mosaicism resulting from processes such as lyonization or somatic postzygotic mutation. Lichen striatus and blaschkitis are two such acquired inflammatory skin disorders that are distinguished in the literature by age of onset, location, and histopathological features. Lichen striatus is typically observed on the extremities of children and is characterized by lichenoid papules that appear in a linear distribution along Blaschko’s lines. Microscopic examination typically shows spongiosis, as well as lichenoid and periadnexal inflammation. Blaschkitis more commonly occurs in adults and frequently involves the truncal areas, including the chest and abdomen. Microscopic examination typically shows spongiotic dermatitis. We describe a young man with a linear eruption extending from the flexor aspect of his right wrist to his central chest, which has features of both lichen striatus and blaschkitis. Both lichen striatus and blaschkitis are self-limited diseases that may resolve within months. It has been suggested that lichen striatus and blaschkitis are not separate entities, but rather the two endpoints within the spectrum of blaschkolinear acquired inflammatory skin eruption (BLAISE). The overlapping features of lichen striatus and blaschkitis in our patient demonstrate the spectrum of clinical and pathologic features in patients with BLAISE.

Linearized solar elastosis of the legs: A novel presentation and review of the literature

There exists a spectrum of solar elastotic variants based on the clinical and histopathologic findings. We present here a peculiar case of solar elastosis that is unusual in its anatomic location, relative lack of background actinic damage, and pattern of linearization. Its presentation suggests that other factors in addition to ultraviolet radiation may play a role in the pathogenesis of solar elastosis.

[Skin biopsy of inflammatory skin diseases in childhood-when is it reasonable?]

Compared with adulthood, inflammatory skin diseases are relatively rarely biopsied in children. Apart from the invasiveness of the procedure, the required local anesthesia, and the risks of infection and scarring, the psychological trauma of the operation has a higher impact in childhood. If a biopsy is performed, expectations towards the dermatopathology report are high. However, the evaluation of biopsies taken from children is challenging for the dermatopathologist: on the one hand, because the biopsies are often tiny or just superficial shaves and, on the other hand, because criteria for evaluation have mostly been developed from findings in adult biopsy specimens. In children, the immune system is still in the process of maturation and, therefore, infiltrates in the skin may look different from those seen in adults; however, knowledge about that is very limited to date. Moreover, numerous rare genodermatoses may manifest themselves first in childhood and need to be considered in the differential diagnosis while experience with them is often limited. Starting from the clinical presentation, this article presents histopathological features of possible differential diagnoses in order to demonstrate the value or necessity of a skin biopsy in a pediatric patient. In addition, communication with parents and child, methods of local anesthesia and biopsy techniques will be considered.

Histopathology of Cutaneous Inflammatory Disorders in Children

Inflammatory dermatoses encompass a variety of histologic patterns that affect different portions of the skin. In spongiotic, psoriasiform, lichenoid, pityriasiform, and blistering disorders, there are predominately epidermal and junctional activities with variable superficial dermal inflammation. Hypersensitivity reactions can show either epidermal or mostly dermal changes depending on whether the exposure of the exogenous allergen occurs through an external or internal route, respectively. Exceptions include erythema multiforme and Stevens-Johnson syndrome/toxic epidermal necrolysis, where the etiology is often due to infection or ingested medications, but the histologic features are almost exclusively confined to the epidermis and dermoepidermal junction. Autoimmune disorders are unique in that lesions typically incorporate a mixture of epidermal and dermal inflammatory patterns with periadnexal inflammation, while the vast majority of vasculitis/vasculopathy and alopecia have changes limited to only the vessels and hair follicles, respectively. It is critical to recognize that a relatively limited number of histologic patterns are seen in a large array of clinical entities. Therefore, clinicopathologic correlation and careful examination of histologic details are of the utmost importance when evaluating skin biopsies for inflammatory disorders.

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.

Linear lupus erythematosus profundus as an initial manifestation of systemic lupus erythematosus in a child

The case of a 13-year-old Caucasian girl with a 1-year history of a linear plaque on her thigh is reported. Histopathologic examination of the incisional biopsy tissue established the diagnosis of lupus erythematosus panniculitis. Six months later she developed the clinical and laboratory criteria for the diagnosis of systemic lupus erythematosus (SLE). She was treated with azathioprine and oral prednisolone, with a favorable clinical outcome. Our case illustrates a child with linear lupus erythematosus profundus as an initial manifestation of SLE. To our knowledge, only eight other cases of linear lupus erythematosus profundus have been reported in the literature, five in children. In contrast to our patient, none of those cases progressed to SLE during the reported follow-up period. The authors report this case to illustrate an unusual superimposed segmental manifestation of an inflammatory polygenic disorder.

Two cases of lichen striatus with prolonged active phase

Lichen striatus is a localized, eczematous disorder distributed along the lines of Blaschko, primarily affecting children. In the literature, lesions have been described as having an active phase of inflamed lesions for 6 to 12 months followed by flattening and persistent pigmentary alteration. We describe two girls who had prolonged active-phase lesions for 2.5 and 3.5 years, respectively. Practitioners should be aware that lesions of lichen striatus may have a prolonged active phase.

Facial blaschkitis: case and review

We report on a 15-year-old female with a 3-month history of a pruritic, erythematous cutaneous eruption on the right cheek and perioral area. The lesion had a linear distribution following the lines of Blaschko. Histopathological findings and direct immunofluorescence were compatible with chronic cutaneous lupus erythematosus (LE). Treatment with topical steroids and systemic antimalarial agents over 2 months showed hardly any improvement contrary to similar cases reported in the literature in the past. Histological findings move this case close to LE. However, the unusual clinical presentation as well as the resistance to antimalarial drugs do not fully allow to confirm this suspicion. Therefore, we recommend to call this new entity LE-like facial Blaschkitis of the adult.

Lichen striatus on adult

Lichen Striatus is an uncommon inflammatory skin eruption of unknown etiology. It rarely affects adults, and it is characterized by abrupt onset of coalescent papules, in a linear disposition, usually on the extremities. Histopathology shows lichenoid reaction involving follicles and glands. Occasionally, there is overlap with linear lichen planus and "blaschkitis", the main differential diagnoses. It is reported here the case of an adult woman with erythematous violaceous papules on the right side of the neck and face, diagnosed with lichen striatus by clinical and histopathological correlation. The atypical findings and the diagnostic difficulty are discussed.

A case of juvenile dermatomyositis manifesting inflammatory epidermal nevus-like skin lesions: unrecognized cutaneous manifestation of blaschkitis?

BACKGROUND

Juvenile dermatomyositis is potentially life threatening rare autoimmune illness that mainly affects muscle and skin. Cutaneous features are useful in establishing the diagnosis of this disease.

CASE SUMMARY

We report an 8-year-old male juvenile dermatomyositis who presented epidermal nevus like-lesions on the back of the right thigh. Characteristic cutaneous changes such as Gottron's papules of the hand, heliotrope rash of the eyelids, and poikiloderma-like lesions on the back were observed. Diagnosis of juvenile dermatomyositis was made by positive muscle biopsy and magnetic resonance imaging findings and typical cutaneous manifestations. However, epidermal nevus-like skin lesions, an acquired inflammatory dermatosis that follows Blaschko lines, seen in this case have been rarely reported in the literatures.

DISCUSSION

We would like to report this case and discuss about the significance and pathogenesis of this rare cutaneous manifestation like Blaschkitis in juvenile dermatomyositis.

Transient linear eruption: asymmetric periflexural exanthem or blaschkitis

We report the case of a 4-year-old boy who presented with a transient extensive eczematous eruption on the left side of his trunk and extremities, with clear demarcation in the midline. The eruption started to resolve without any sequelae in 4 weeks. The history and clinical findings suggest that this transient eruption could have been either a case of unilateral blaschkitis in childhood or asymmetric periflexural exanthem.

Blaschkitis in children - a new entity?

Blaschkitis is an acquired, rare dermatitis that follows the lines of Blaschko. Many consider blaschkitis as a variant of lichen striatus, although authors felt that it is a separate entity. A 2½-year-old girl presented with multiple grouped papules along the lines of Blaschko on her trunk. The main differences to lichen striatus are illustrated. Our case supports the hypothesis that blaschkitis is an entity of its own.

Tiers of clonal organization in the epidermis: the epidermal proliferation unit revisited

As one of the most proliferative tissues in adult mammals, the epidermis is a good example of the precise regulation necessary between stem cell self-renewal and differentiation. The epidermis is derived from ectodermal progenitor cells and contains three distinct classes of cells: epidermal stem cells which are capable of infinite rounds of cell division; their immediate descendants, transient amplifying cells, which are capable of numerous but finite rounds of cell division; and finally, non-dividing, differentiating cells (Aberdam in Cell and Tissue Research 331:103-107, 2008). This proliferative hierarchy must be tightly regulated both temporally and spatially during epidermal development and homeostasis in order to prevent uncontrolled growth leading to hyperproliferative states and/or tumorigenesis. Historically, the most basic unit of epidermal proliferation has been described as the epidermal proliferation unit (EPU). The EPU, as originally characterized by Christophers, Potten and Mackenzie, is a proliferation unit consisting of approximately 10 basal cells with a clonogenic cell in the center and overlaid by the suprabasal and corneocyte progeny (reviewed in Potten, C. S. (1974). The epidermal proliferative unit: the possible role of the central basal cell. Cell and Tissue Kinetics, 7(1), 77-88). Numerous researchers have identified this classical EPU structure, consisting of approximately 20 cells, in a variety of mammalian skin sources. Recently however, lineage analyses have provided evidence for much larger clonal epidermal units consisting of hundreds to thousands of cells. Furthermore, cutaneous mosaicism as well as a variety of cutaneous pathologies indicate that clonal areas extend to whole patches of mammalian skin many centimeters across. In this review we revisit four decades of experimental evidence and put forward a model of clonal units derived from multiple classes of epidermal progenitors ranging from the largest and most primitive units, clonal ectodermal units, to epidermal stem cell units, and finally, to the most basic structural unit, the EPU.