Linear Scleroderma Along Blaschko's Lines in a Patient with Systematized Morphea

Unravelling morphoea aetiopathogenesis by next-generation sequencing of paired skin biopsies

BACKGROUND

Morphoea can have a significant disease burden. Aetiopathogenesis remains poorly understood, with very limited existing genetic studies. Linear morphoea (LM) may follow Blascho's lines of epidermal development, providing potential pathogenic clues.

OBJECTIVE

The first objective of this study was to identify the presence of primary somatic epidermal mosaicism in LM. The second objective was tTo explore differential gene expression in morphoea epidermis and dermis to identify potential pathogenic molecular pathways and tissue layer cross-talk.

METHODOLOGY

Skin biopsies from paired affected and contralateral unaffected skin were taken from 16 patients with LM. Epidermis and dermis were isolated using a 2-step chemical-physical separation protocol. Whole Genome Sequencing (WGS; n = 4 epidermal) and RNA-seq (n = 5-epidermal, n = 5-dermal) with gene expression analysis via GSEA-MSigDBv6.3 and PANTHER-v14.1 pathway analyses, were performed. RTqPCR and immunohistochemistry were used to replicate key results.

RESULTS

Sixteen participants (93.8% female, mean age 27.7 yrs disease-onset) were included. Epidermal WGS identified no single affected gene or SNV. However, many potential disease-relevant pathogenic variants were present, including ADAMTSL1 and ADAMTS16. A highly proliferative, inflammatory and profibrotic epidermis was seen, with significantly-overexpressed TNFα-via-NFkB, TGFβ, IL6/JAKSTAT and IFN-signaling, apoptosis, p53 and KRAS-responses. Upregulated IFI27 and downregulated LAMA4 potentially represent initiating epidermal 'damage' signals and enhanced epidermal-dermal communication. Morphoea dermis exhibited significant profibrotic, B-cell and IFN-signatures, and upregulated morphogenic patterning pathways such as Wnt.

CONCLUSION

This study supports the absence of somatic epidermal mosaicism in LM, and identifies potential disease-driving epidermal mechanisms, epidermal-dermal interactions and disease-specific dermal differential-gene-expression in morphoea. We propose a potential molecular narrative for morphoea aetiopathogenesis which could help guide future targeted studies and therapies.

Kawasaki Disease (KD) With Linear Facial Erythema Coinciding With Blaschko’s Lines

Kawasaki disease (KD) is a self-limited, systemic vasculitis developing in early childhood. Skin findings of KD are polymorphous, varying from diffuse maculopapular eruptions to psoriasiform lesions. We described herein an 18-month-old male patient with KD who presented with linear, facial erythema coinciding with Blaschko’s lines. Parental consent for this case report was obtained in written and verbal form.

Paediatric morphoea: a holistic review. Part 1: epidemiology, aetiopathogenesis and clinical classification

Morphoea, also known as localized scleroderma, is a debilitating fibrosing disorder of uncertain aetiology, affecting the skin and subcutaneous tissues. Paediatric-onset disease is not uncommon and is associated with frequent relapses. The disease has complex pathogenetic mechanisms and multiple clinical subtypes, and affects children of all ages. Recent research has focused on elucidating the disease pathophysiology and identifying measures of disease activity. We performed a literature search on PubMed, MEDLINE and Google Scholar, using keywords such as 'pediatric morphea', 'juvenile localised scleroderma' and 'juvenile systemic sclerosis'. Relevant studies, including randomized trials, reviews of standard current guidelines and original research articles, were selected, and results were analysed before being summarized. In the first of this two-part review, we provide a bird's-eye view of the current literature concerning the epidemiology, aetiopathogenesis and clinical classification of paediatric morphoea; in Part 2, we review the diagnosis, markers of disease activity, management and natural history.

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.

Linear Morphea Mimicking Lichen Striatus in Its Early Presentation

Linear morphea and lichen striatus are distinct conditions that have been linked in only one previous case report. We describe two patients with facial lichen striatus preceding linear morphea at the same site. A possible pathogenic relationship is discussed.

A cross-sectional electromyography assessment in linear scleroderma patients

BACKGROUND

Muscle atrophy and asymmetric extremity growth is a common feature of linear scleroderma (LS). Extra-cutaneous features are also common and primary neurologic involvement, with sympathetic dysfunction, may have a pathogenic role in subcutaneous and muscle atrophy. The aim was investigate nerve conduction and muscle involvement by electromyography in pediatric patients with LS.

METHODS

We conducted a retrospective review of LS pediatric patients who had regular follow up at a single pediatric center from 1997-2013. We selected participants if they had consistently good follow up and enrolled consecutive patients in the study. We examined LS photos as well as clinical, serological and imaging findings. Electromyograms (EMG) were performed with bilateral symmetric technique, using surface and needle electrodes, comparing the affected side with the contralateral side. Abnormal muscle activity was categorized as a myopathic or neurogenic pattern.

RESULTS

Nine LS subjects were selected for EMG, 2 with Parry-Romberg/Hemifacial Atrophy Syndrome, 7 linear scleroderma of an extremity and 2 with mixed forms (linear and morphea). Electromyogram analysis indicated that all but one had asymmetric myopathic pattern in muscles underlying the linear streaks. Motor and sensory nerve conduction was also evaluated in upper and lower limbs and one presented a neurogenic pattern. Masticatory muscle testing showed a myopathic pattern in the atrophic face of 2 cases with head and face involvement.

CONCLUSION

In our small series of LS patients, we found a surprising amount of muscle dysfunction by EMG. The muscle involvement may be possibly related to a secondary peripheral nerve involvement due to LS inflammation and fibrosis. Further collaborative studies to confirm these findings are needed.

Linear morphoea follows Blaschko's lines

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.

Unilateral congenital linear atrophoderma of the leg

We report an infant with depressed, hypopigmented, linear plaques of congenital onset on the lower extremity. The lesions were asymptomatic and the child was otherwise healthy. Despite the clinically obvious change in skin texture and color, histopathologic changes were subtle: a biopsy specimen showed hypopigmentation and a decrease in elastic fibers in the papillary and upper reticular dermis. Diagnoses considered included various congenital syndromes, idiopathic atrophoderma of Pasini and Pierini, and especially, linear atrophoderma of Moulin. However, because of the significant clinical and histopathologic differences when compared to the aforementioned entities, our patient appears to have a unique presentation of congenital linear atrophoderma.