Dermal Nerve Research Articles

How many hair follicles are innervated by one afferent axon? A confocal microscopic analysis of palisade endings in the auricular skin of thy1-YFP transgenic mouse

Hairs are known as a sensory apparatus for touch. Their follicles are innervated predominantly by palisade endings composed of longitudinal and circumferential lanceolate endings. However, little is known as to how their original primary neurons make up a part of the ending. In this study, innervation of the palisade endings was investigated in the auricular skin of thy1-YFP transgenic mouse. Major observations were 1) Only a small portion of PGP9.5-immunopositive axons showed YFP-positivity, 2) All of thy1-YFP-positive sensory axons were thick and myelinated, 3) Individual thy1-YFP-positive trunk axons innervated 4–54 hair follicles, 4) Most palisade endings had a gap of lanceolate ending arrangement, 5) PGP9.5-immunopositive 10–32 longitudinal lanceolate endings were closely arranged. Only a part of them were thy1-YFP-positive axons that originated from 1–3 afferents, and 6) Single nerve bundles of the dermal nerve network included both bidirectional afferents. Palisade endings innervated by multiple sensory neurons might be highly sensitive to hair movement.

Bandeiraea Simplicifolia Isolectin B4 Binds Mast Cells in Human Skin and this Latter Binding is Up-Regulated in Patients with Atopic Dermatitis and Stinging

The causes of sensitive skin, a common problem in patients with acne rosacea or atopic dermatitis, and even in individuals without obvious skin disease, remain unclear. The density of nerve fibers, levels of neuropeptides as well as the nature and number of mast cells may play a role in this connection. Unmyelinated nociceptive neurons mediate most of the sensation from the skin, and a large part of these neurons are characterized by their ability to bind the lectin Banderiaea simlicifolia isolectin IB4 (IB4). We therefore, examined whether the distribution and extent of IB4-labeling is modified in patients with enhanced skin sensitivity compared to controls. We used immunohistochemistry to label. IB4-binding elements in skin biopsies from patients with atopic dermatitis. Of the 20 patients with atopic dermatitis subjected to the stinger test, 11 were stinger-positive and 9 stinger-negative. Stinger-positive papillary dermis contained a significantly larger number of IB4 binding cells, which were shown by double staining for tryptase as well to be mast cells. Binding of IB4 was also detected on dermal nerves associated with adnexa structures in the stratium corneum and on keratinocytes. Since IB4 binds to specific carbohydrate moieties, the increased binding of IB4 by mast cells indicates that alterations in their glycoprotein composition may play a pathophysiological role in connection with stinging.

Cytokine and Protein Markers of Leprosy Reactions in Skin and Nerves: Baseline Results for the North Indian INFIR Cohort

BackgroundPrevious studies investigating the role of cytokines in the pathogenesis of leprosy have either been on only small numbers of patients or have not combined clinical and histological data. The INFIR Cohort study is a prospective study of 303 new multibacillary leprosy patients to identify risk factors for reaction and nerve damage. This study characterised the cellular infiltrate in skin and nerve biopsies using light microscopic and immunohistochemical techniques to identify any association of cytokine markers, nerve and cell markers with leprosy reactions.Methodology/Principal FindingsTNF-α, TGF-β and iNOS protein in skin and nerve biopsies were detected using monoclonal antibody detection immunohistochemistry techniques in 299 skin biopsies and 68 nerve biopsies taken from patients at recruitment. The tissues were stained with hematoxylin and eosin, modified Fite Faraco, CD68 macrophage cell marker and S100.Conclusions/SignificanceHistological analysis of the biopsies showed that 43% had borderline tuberculoid (BT) leprosy, 27% borderline lepromatous leprosy, 9% lepromatous leprosy, 13% indeterminate leprosy types and 7% had no inflammation. Forty-six percent had histological evidence of a Type 1 Reaction (T1R) and 10% of Erythema Nodosum Leprosum. TNF-α was detected in 78% of skin biopsies (181/232), iNOS in 78% and TGF-β in 94%. All three molecules were detected at higher levels in patients with BT leprosy. TNF-α was localised within macrophages and epithelioid cells in the granuloma, in the epidermis and in dermal nerves in a few cases. TNF-α, iNOS and TGF-β were all significantly associated with T1R (p<0.001). Sixty-eight nerve biopsies were analysed. CD68, TNF-α and iNOS staining were detectable in 88%, 38% and 28% of the biopsies respectively. The three cytokines TNF-α, iNOS and TGF-β detected by immunohistochemistry showed a significant association with the presence of skin reaction. This study is the first to demonstrate an association of iNOS and TGF-β with T1R.

Unmyelinated and myelinated skin nerve damage in Guillain–Barré syndrome: Correlation with pain and recovery

We performed a prospective study in 32 patients with Guillain–Barré syndrome (GBS) or its variants to correlate intraepidermal nerve fiber density (IENFD) at the distal leg and lumbar region with pain, autonomic dysfunction, and outcome. In the acute phase, IENFD was reduced in 60% and 61.9% of patients at the distal leg and lumbar region, respectively. In the acute phase, 43.7% of patients complained of neuropathic pain. Their IENFD at the distal leg was significantly lower than in patients without pain ( P < .001) and correlated with pain intensity ( r s = −0.51; P = .003). Intriguingly, also patients with the pure motor variant of GBS and pain had low IENFD. At 6-month follow-up, only 3 patients complained of persisting neuropathic pain, whereas 3 patients reported late-onset pain symptoms. IENFD in the acute phase did not predict presence or intensity of pain at 6-month follow-up. IENFD in the acute phase did not correlate with clinical dysautonomia or GBS severity at nadir. However, it correlated with poorer GBS disability score at 6 months ( P = .04), GBS score at nadir ( P = .03), and clinically probable dysautonomia ( P = .004). At 6-month follow-up, median IENFD remained significantly low both at the distal leg ( P = .024) and lumbar region ( P = .005). Double and triple staining confocal microscope studies showed diffuse damage of myelinated dermal nerves along with axonal degeneration, and mononuclear cell infiltration. Unmyelinated and myelinated skin nerves are diffusely affected in GBS and its variants, including the pure motor form. IENFD declines early, remains low over time, correlates with pain severity in the acute phase, and may predict long-term disability.

C-Jun expression in human neuropathies: a pilot study

Schwann cell dedifferentiation following nerve injury is important to permit neural survival and axonal regrowth. Animal studies have shown that the transcription factor c-Jun is upregulated in Schwann cells of injured and pathological nerves where it acts as an important regulator of Schwann cell plasticity, promoting dedifferentiation and demyelination. This pilot immunohistochemical study investigates whether c-Jun is also upregulated in human neuropathies. We examined c-Jun expression in normal and diseased human nerves, as well as in dermal myelinated nerve fibres. Our findings show that although as predicted c-Jun is rarely expressed in normal nerves, it is expressed in Schwann cell nuclei of pathological nerves as predicted by animal studies. Pathological dermal myelinated nerve fibres also show clear nuclear c-Jun expression. Further studies of c-Jun expression will help clarify its role in human neuropathies.

Morphometry of dermal nerve fibers in human skin

# {#article-title-2} “Morphometry of dermal nerve fibers in human skin”1 is the first comprehensive analysis of nerve fibers in both the dermal and the intraepidermal portions of 3-mm punch biopsies using widely available laboratory techniques. Expanding the analysis of skin biopsies to include dermal as well as intraepidermal regions might allow 1) examination of longer segments of axons in addition to measures of fiber density, 2) expansion of the range of axon types measured, including larger diameter fibers and axons that innervate mechanoreceptors and sweat glands, and 3) comparison of changes in the distal limb extreme axon terminals with those in more proximal regions. The report provides clear evidence that the assessment of dermal nerve fibers is feasible; it uses …

Matrix Metalloproteinase-8 Is Involved in Dermal Nerve Growth: Implications for Possible Application to Pruritus from In Vitro Models

Cutaneous nerve density is related to abnormal itch perception in dermatoses, such as atopic dermatitis and xerosis. However, the mechanisms underlying the elongation of dermal nerve fibers within the interstitial collagen (CoL) matrix are poorly understood. In this study, a culture system of rat dorsal root ganglion neurons consisting of type I CoL and a Boyden chamber containing a nerve growth factor (NGF) concentration gradient was used. Nerve fibers penetrating into type I CoL gel were observed in the presence of the NGF concentration gradient. Levels of matrix metalloproteinase-8 (MMP-8) mRNA and protein were increased in the cultured neurons and the conditioned medium, respectively. The nerve fiber penetration was dose dependently inhibited by MMP-8 blockers. Moreover, MMP-8 immunoreactivity was partially localized at growth cones in NGF-responsive nerve fibers. Semaphorin 3A stimulation also showed the opposite effects on these NGF-dependent events. Intriguingly, MMP-8 expression was upregulated by type I and III CoLs, which are substrates for this enzyme. These results suggested that MMP-8 is involved in sensory nerve growth within the interstitial CoL matrix through modulation by the axonal guidance molecules and/or extracellular matrix components. These findings provide insight into the development of pruritus involving skin nerve density.

Morphometry of dermal nerve fibers in human skin

We aimed to assess the innervation density of dermal nerves in human skin biopsies by bright-field immunohistochemistry. The size of dermal area where nerve length was quantified was validated in 30 skin biopsy sections (5 controls and 5 patients with small-fiber neuropathy [SFN]). It was obtained dividing an area of 200-μm depth from the dermal-epidermal junction into 4 equal portions. The length of dermal nerves (DNFL) was measured into 150 sections (25 controls and 25 patients with SFN) and values per millimeter of epidermis (DNFL/mm) and dermal area (DNFL/mm2) were obtained. Age- and gender-matched normative values of intraepidermal nerve fiber (IENF) density were used as gold standard to calculate the performance of dermal nerve morphometry. Patients showed significantly lower DNFL (1.96 mm ± 0.96 SD), DNFL/mm (0.65 ± 0.29 SD), and DNFL/mm2 (3.75 ± 1.7 SD) than controls (DNFL 3.52 mm ± 1.31 SD, 5th percentile 2.05; DNFL/mm 1.25 ± 0.39, 5th percentile 0.71; DNFL/mm2 7.07 ± 2.41 SD, 5th percentile 3.95). Sensitivity, specificity, and percentage of individuals correctly classified were 75.8%, 73.9%, and 74.8% for DNFL, 75%, 80%, and 77.7% for DNFL/mm, and 75.8%, 80.2%, and 78.1% for DNFL/mm2. Receiver operator characteristic area analysis confirmed the excellent discrimination (0.8-0.9) between patients and controls. Dermal nerve morphometry significantly correlated with IENF density. Spearman rank correlation demonstrated good agreement for interobserver analysis (0.87-0.89), and between DNFL and IENF densities (0.71-0.73; p < 0.0001). We provided a reliable method to quantify the innervation density of dermal nerves that might improve the diagnostic yield of skin biopsy.

Axonal fluorescence quantitation provides a new approach to assess cutaneous innervation

We present a novel approach to quantify skin innervation by measuring the PGP 9.5 immunoreactive (PGP-ir) fluorescence corresponding to axons within the epidermis and dermis. The skin biopsies from 35 controls and 45 small fiber neuropathy (SFN) patients were included. In 50-μm free-floating sections, we determined the intraepidermal nerve fiber density (IENFD) by direct fluorescence visualization and captured 2-μm thick individual optical sections using the same confocal microscope and magnification. We measured the fluorescence of the PGP-ir axons in both, epidermal and dermal area by using the ImageJ software. There was good interobserver and intraobserver reliability of PGP-ir measures, similar than for IENFD. The PGP-ir axons were found decreased in patients with SFN (1.1‰ and 9.0‰ respectively for epidermal and dermal area in contrast to 2.2‰ and 16.0‰, respectively to controls). The area under the ROC curve was 0.90 for the IENFD, 0.84 for epidermal PGP-ir axons and 0.70 for dermal PGP-ir axons. There was a positive correlation between the IENFD and the PGP-ir axons at epidermis (Spearman Rho = 0.66, p < 0.001) as well as for the dermal nerve length and the PGP-ir axons at dermis (Spearman Rho = 0.45, p < 0.05). This method is also particularly adequate for the quantitation of dermal nerve fibers. We conclude that quantifying the fluorescent PGP-ir axons could help to assess skin innervation (dermal and epidermal nerve fibers) in patients with SFN.

Reduced intraepidermal nerve fibre density in lesional and nonlesional prurigo nodularis skin as a potential sign of subclinical cutaneous neuropathy

Prurigo nodularis (PN) is a highly pruritic condition characterized by multiple hyperkeratotic nodules. Previous immunohistochemical studies demonstrated increased numbers of dermal nerve fibres. Given that the sensation of pruritus is transmitted mainly by thin, unmyelinated epidermal nerves, the aim of our study was to investigate the intraepidermal nerve fibre (IENF) density. Biopsies taken from lesional and nonlesional skin of 53 patients (37 women and 16 men; mean ± SD age 60·6 ± 14·9 years) with PN of diverse origin were immunostained for protein gene product 9·5. According to the guideline of the European Federation of Neurological Societies, the IENF density per millimetre was determined and compared with that in 20 healthy volunteers. Lesional and uninvolved PN skin biopsies showed significantly decreased IENF density (P < 0·001) regardless of patient age, origin of PN, intensity or quality of pruritus. Hypoplasia of epidermal sensory nerves independently of clinical parameters is a new finding in PN and suggests involvement of epidermal nerves in PN pathophysiology. To date, it cannot be ruled out that reduced IENF density is due to repeated scratching. However, the presence of hypoplasia in nonlesional PN skin suggests the presence of a subclinical small fibre neuropathy.

Differential gene expression profiles of neurothekeomas and nerve sheath myxomas by microarray analysis

Neurothekeomas and dermal nerve sheath myxomas have previously been considered related cutaneous neoplasms of peripheral nerve sheath origin based on light microscopic similarities. However, recent immunohistochemical and ultrastructural data indicate nerve sheath myxomas exhibit true nerve sheath differentiation, whereas no such compelling evidence exists for neurothekeomas. Although neurothekeomas lack a specific immunohistochemical profile, similar antigen expression and histopathologic patterns suggest neurothekeomas may be categorized as fibrohistiocytic tumors. To date, no known molecular studies have examined the histogenetic relationship of these tumors. We report the first microarray-based gene expression profile study of these entities on formalin-fixed paraffin-embedded tissues. Cases of dermal schwannomas, dermal nerve sheath myxomas, myxoid/mixed/cellular neurothekeomas, and cellular fibrous histiocytomas diagnosed in the past 3 years were identified in our database. Archival formalin-fixed paraffin-embedded tissue from 28 patients was selected for microarray analysis (seven schwannomas, five nerve sheath myxomas, nine myxoid/mixed/cellular neurothekeomas and seven cellular fibrous histiocytomas). Following tumor RNA isolation, amplification and labeling using commercially available kits, labeled targets were hybridized to the Affymetrix GeneChip Human Genome U133 Plus 2.0 Array (Santa Clara, CA, USA). Acquisition of array images and data analyses was performed using appropriate software. Hierarchical clustering and principal component analysis demonstrated discrete groups, which correlated with histopathologically identified diagnoses. Dermal nerve sheath myxomas demonstrate very similar molecular genetic signatures to dermal schwannomas, whereas neurothekeomas of all subtypes more closely resemble cellular fibrous histiocytomas. We are the first to report distinct gene expression profiles for nerve sheath myxomas and neurothekeomas, which further substantiates the argument that these are separate entities. Our molecular data confirms that dermal nerve sheath myxomas are of peripheral nerve sheath origin, and suggests that neurothekeomas may actually be a variant of fibrous histiocytomas.

Pathogenesis of pruritus

The pathogenesis of acute and chronic (> 6 weeks duration) pruritus is complex and involves in the skin a network of resident cells (e. g., mast cells, keratinocytes, sensory neurons) and transient inflammatory cells (e. g., eosinophils). Though pruritus and pain show overlapping mechanisms, recent studies have provided evidence that pruritus and pain pathogenesis differ in important points. In the skin, the sensory C-nerve fibers have been investigated intensively. Several classes of histamine-sensitive or histamine-insensitve C-fibers have been described. Epidermal and dermal sensory nerve fibres are now assumed to be of major importance in pruritus induction. They interact with keratinocytes, inflammatory cells such as T lymphocytes, eosinophils and basophils which have been shown to release multiple pruritogenic mediators (e.g., nerve growth factor, interleukin-31) which lead to activation, sensitization and sprouting of skin nerves. Specific receptors have been discovered on cutaneous and spinal neurons to be exclusively involved in the processing of pruritic signals. Just recently, the gastrin-releasing peptide receptor (GRPR) was identified on spinal neurons that are crucially involved in pruritus but not pain processing. Chronic pruritus is notoriously difficult to treat. Newer insights into the underlying pathogenesis of pruritus have enabled novel treatment approaches that target the pruritus-specific pathophysiological mechanism. For example, kappa-opioid receptor agonists and neurokinin-1 antagonists have been found to relieve chronic pruritus.

Effects of stress memory by fear conditioning on nerve-mast cell circuit in skin

Inflammatory skin disorder aggravates when a horrific memory is evoked, but the mechanism of this effect is unclear. The objective of the present study was to examine the effects of evocation of a horrific memory on the skin and mast cells in an animal model. A sound stimulus linked to an electric shock was given to C57BL/6 mice (7-week old, males). One, 3 and 5 days later, the mice received the sound stimulus again. The reactions of mice that received the initial sound stimulus were compared with those of mice that did not receive the initial stimulus. A freezing phenomenon was observed when the sound stimulus was given to mice that received the initial stimulus, which indicated evocation of a past memory of fear. The degranulation rate of dermal mast cells and the length of substance P (SP)-positive nerve fibers of the skin significantly increased on days 1 and 3, the SP level decreased significantly, and the number of SP-expressing cells in the dorsal root ganglion significantly increased on day 1. These findings suggest that prior experience of severe stress linked to a stimulus subsequently evokes fear associated with the same stimulus and results in activation of dermal mast cells and skin nerves.

Foot pad skin biopsy in mouse models of hereditary neuropathy

Numerous transgenic and knockout mouse models of human hereditary neuropathies have become available over the past decade. We describe a simple, reproducible, and safe biopsy of mouse skin for histopathological evaluation of the peripheral nervous system (PNS) in models of hereditary neuropathies. We compared the diagnostic outcome between sciatic nerve and dermal nerves found in skin biopsy (SB) from the hind foot. A total of five animal models of different Charcot-Marie-Tooth neuropathies, and one model of congenital muscular dystrophy associated neuropathy were examined. In wild type mice, dermal nerve fibers were readily identified by immunohistochemistry, light, and electron microscopy and they appeared similar to myelinated fibers in sciatic nerve. In mutant mice, SB manifested myelin abnormalities similar to those observed in sciatic nerves, including hypomyelination, onion bulbs, myelin outfolding, redundant loops, and tomacula. In many strains, however, SB showed additional abnormalities—fiber loss, dense neurofilament packing with lower phosphorylation status, and axonal degeneration—undetected in sciatic nerve, possibly because SB samples distal nerves. SB, a reliable technique to investigate peripheral neuropathies in human beings, is also useful to investigate animal models of hereditary neuropathies. Our data indicate that SB may reveal distal axonal pathology in mouse models and permits sequential follow-up of the neuropathy in an individual mouse, thereby reducing the number of mice necessary to document pathology of the PNS. © 2010 Wiley-Liss, Inc.

Pathology and functional diagnosis of small-fiber painful neuropathy.

Small-fiber sensory neuropathy with neuropathic pain had been a diagnostic challenge for neurologists. We and several groups have developed skin biopsy with quantitation of intraepidermal nerve fiber (IENF) density as a diagnostic approach. In the skin with small-fiber sensory neuropathy, there are pathological hallmarks: reduced IENF density with degeneration of subepidermal nerve plexuses and dermal nerves. Skin denervation is a major presentation of diabetic neuropathy and inflammatory neuropathies including Guillain-Barr syndrome and chronic inflammatory demyelinating polyneuropathy. The skin biopsy approach also provides an opportunity to examine dermal vasculature and inflammatory vasculopathy is demonstrated in vasculitic neuropathy, systemic lupus erythematosus, and eosinophilia-associated neuropathy. In addition to neuropahtologic evidence, the functional consequences of cutaneous nerve degeneration can be assessed with quantitative sensory testing (QST), contact heat evoked potential (CHEP), and functional magnetic resonance imaging (fMRI). One major etiology of small-fiber sensory neuropathy is familial amyloid polyneuropathy caused by mutations of transthyretin (TTR). We recently conducted studies on a large cohort of unique TTR mutation on Ala97Ser in Taiwan. These patients had significant skin denervation in addition to motor and autonomic neuropathy. Taken together, the skin biopsy with quantitation of IENF density provides diagnostic utility for small-fiber sensory neuropathy and the combination of psychophysical, physiological, and neuroimaging examinations offer comprehensive assessments for patients with neuropathic pain due o cutaneous nerve degeneration.

Die Talgdrüse

The development and function of the sebaceous gland in the fetal and neonatal periods appear to be regulated by maternal androgens and by endogenous steroid synthesis, as well as by other morphogens. The most apparent function of the glands is to excrete sebum. A strong increase in sebum excretion occurs a few hours after birth; this peaks during the first week and slowly subsides thereafter. A new rise takes place at about age 9 years with adrenarche and continues up to age 17 years, when the adult level is reached. The sebaceous gland is a target organ but also an important formation site of hormones, and especially of active androgens. Hormonal activity is based on an hormone (ligand)-receptor interaction, whereas sebocytes express a wide spectrum of hormone receptors. Androgens are well known for their effects on sebum excretion, whereas terminal sebocyte differentiation is assisted by peroxisome proliferator-activated receptor ligands. Estrogens, glucocorticoids, and prolactin also influence sebaceous gland function. In addition, stress-sensing cutaneous signals lead to the production and release of corticotrophin-releasing hormone from dermal nerves and sebocytes with subsequent dose-dependent regulation of sebaceous nonpolar lipids. Among other lipid fractions, sebaceous glands have been shown to synthesize considerable amounts of free fatty acids without exogenous influence. Atopic dermatitis, seborrheic dermatitis, psoriasis and acne vulgaris are some of the disease on which pathogenesis and severity sebaceous lipids may or are surely involved.

Low density of sympathetic nerve fibers relative to substance P-positive nerve fibers in lesional skin of chronic pruritus and prurigo nodularis

In prurigo nodularis (PN), an increase in the density of dermal substance P-positive (SP+) sensory nerve fibers has been demonstrated. In addition, the density of sympathetic nerve fibers is unchanged. We aimed to investigate the density and balance of sensory and sympathetic dermal nerves in pruritus on normally appearing skin in comparison to PN. In a parallel investigation in lesional and non-lesional skin routine histological and immunofluorescence staining against SP and tyrosine hydroxylase (TH) were performed. We found an increased density of dermal SP+ nerve fibers in PN and also in pruritus relative to sympathetic nerve fibers in affected areas compared to the unaffected site. The density of SP+ and TH+ nerves did not correlate with clinical parameters such as itch quality, duration or intensity. Sparse lymphocytic infiltration as found in affected pruritus skin may be a source of nerve growth factor and explain the hyperinnervation. Similar to the situation in PN, chronic pruritus lesions also demonstrate a preponderance of SP+ sensory nerve fibers relative to sympathetic nerve fibers, which probably acts as a causal pro-inflammatory signal in development of pruritus. These findings suggest new therapeutic approaches in patients with chronic pruritus.

Small fiber neuropathy in female patients with fabry disease

Recent studies suggest that heterozygous female Fabry disease (FD) patients develop peripheral neuropathy. We used skin biopsy to define somatic and autonomic peripheral nerve characteristics in 21 females with FD who were mainly asymptomatic and had normal renal function. Somatic epidermal and dermal autonomic nerve fiber reductions were found, prevalently in the leg, and no differences were found between symptomatic and asymptomatic individuals. Our findings suggest that females with FD, although asymptomatic, may have somatic and autonomic small fiber neuropathy.

IgG/IgE bullous pemphigoid with CD45 lymphocytic reactivity to dermal blood vessels, nerves and eccrine sweat glands

Context:Bullous pemphigoid (BP), the most common autoimmune blistering disease, is mediated by autoantibodies. BP primarily affects the elderly and is characterized by the development of urticarial plaques surmounted by subepidermal blisters, and the deposition of immunoglobulins and complement at the basement membrane zone (BMZ) of the skin. BP is immunologically characterized by the development of autoantibodies targeting two structural proteins of the hemidesmosomes, BP180 (collagen XVII) and BP230 (BPAG1).Case Report:A 63 -year-old Caucasian female patient was evaluated for a 4 day history of several itching, erythematous blisters on her extremities. Biopsies for hematoxylin and eosin (H&E) examination, as well as Periodic acid-Schiff (PAS), immunohistochemistry (IHC) and direct immunofluorescence (DIF) analysis were performed.Results:H&E demonstrated a subepidermal blister, with partial re-epithelialization of the blister floor. Within the blister lumen, numerous neutrophils were present, with occasional eosinophils and lymphocytes also noted. Within the dermis, a mild, superficial, perivascular and periadnexal infiltrate of lymphocytes, histiocytes and occasional eosinophils was identified, with mild perivascular leukocytoclastic debris. The PAS stain was positive at the BMZ, and around selected blood vessels, nerves and sweat glands. DIF revealed linear deposits of IgG and Complement/C3 and fibrinogen at the BMZ, and around selected dermal nerves, blood vessels and sweat glands. Strong granular deposits of IgE were also observed, colocalizing with monoclonal antibodies to Collagen IV (CIV). By IHC, positive CD45 staining of lymphocytes was seen surrounding selected dermal blood vessels, eccrine sweat glands, and nerves.Conclusion:The patient displayed IgG, IgE, and fibrinogen autoantibodies against the BMZ, as well as around some dermal nerves and sweat glands; their binding in the skin could trigger complement activation. In addition, the role of the dermal CD45 positive lymphocytes warrants further investigation.

Shortened internodal length of dermal myelinated nerve fibres in Charcot-Marie-Tooth disease type 1A

Charcot-Marie-Tooth disease type 1A is the most common inherited neuropathy and is caused by duplication of chromosome 17p11.2 containing the peripheral myelin protein-22 gene. This disease is characterized by uniform slowing of conduction velocities and secondary axonal loss, which are in contrast with non-uniform slowing of conduction velocities in acquired demyelinating disorders, such as chronic inflammatory demyelinating polyradiculoneuropathy. Mechanisms responsible for the slowed conduction velocities and axonal loss in Charcot-Marie-Tooth disease type 1A are poorly understood, in part because of the difficulty in obtaining nerve samples from patients, due to the invasive nature of nerve biopsies. We have utilized glabrous skin biopsies, a minimally invasive procedure, to evaluate these issues systematically in patients with Charcot-Marie-Tooth disease type 1A (n = 32), chronic inflammatory demyelinating polyradiculoneuropathy (n = 4) and healthy controls (n = 12). Morphology and molecular architecture of dermal myelinated nerve fibres were examined using immunohistochemistry and electron microscopy. Internodal length was uniformly shortened in patients with Charcot-Marie-Tooth disease type 1A, compared with those in normal controls (P < 0.0001). Segmental demyelination was absent in the Charcot-Marie-Tooth disease type 1A group, but identifiable in all patients with chronic inflammatory demyelinating polyradiculoneuropathy. Axonal loss was measurable using the density of Meissner corpuscles and associated with an accumulation of intra-axonal mitochondria. Our study demonstrates that skin biopsy can reveal pathological and molecular architectural changes that distinguish inherited from acquired demyelinating neuropathies. Uniformly shortened internodal length in Charcot-Marie-Tooth disease type 1A suggests a potential developmental defect of internodal lengthening. Intra-axonal accumulation of mitochondria provides new insights into the pathogenesis of axonal degeneration in Charcot-Marie-Tooth disease type 1A.