Interstitial granulomatous dermatitis with histiocytic pseudorosettes: a new histopathologic pattern in cutaneous borreliosis. Detection of Borrelia burgdorferi DNA sequences by a highly sensitive PCR-ELISA

Palisaded Neutrophilic Granulomatous Dermatitis, Bowel-Associated Dermatosis-Arthritis Syndrome, and Rheumatoid Neutrophilic Dermatitis

Neutrophilic dermatosis is a heterogeneous group of inflammatory skin diseases characterized by the presence of a sterile neutrophilic infiltrate on histopathology. Three specific types of neutrophilic dermatoses are reviewed in this article: palisaded neutrophilic granulomatous dermatitis, bowel-associated dermatosis-arthritis syndrome, and rheumatoid neutrophilic dermatitis. The authors review the literature and highlight the clinical and histopathological features, disease pathogenesis, and the association of these conditions with various systemic diseases such as rheumatoid arthritis, inflammatory bowel disease, and others. A multidisciplinary approach is necessary for the diagnosis and management of these inflammatory skin conditions.

The Free Sign in morphea and other sclerosing disorders: A clue to the presence of early sclerosis?

BACKGROUND

The Floating Sign is a histopathologic clue to the diagnosis of autoimmune sclerosing skin disorders such as morphea and interstitial granulomatous dermatitis (IGD). On the other hand, the "free-floating" sign has been associated with neoplasms, for example, dermatofibroma and interstitial mycosis fungoides. Herein, we report the Free Sign in sclerosing skin disorders.

METHODS

In a case-control study, we applied detailed histopathologic definitions of Floating Sign and Free Sign to assess their presence in morphea, IGD, and other sclerosing disorders.

RESULTS

Free Sign was present in most cases of morphea (46/55, 84%) and IGD (7/13, 54%) but not necrobiosis lipoidica (NL) (6/14, 42.8%) or sclerodermoid graft versus host disease (SGVHD) (2/7, 28.5%). The sensitivity and specificity of Free Sign for morphea versus other disorders was 84% and 56%, respectively. Floating Sign was not identified in most cases: NL (3/14, 21.4%), SGVHD (1/7, 14.2%), morphea (5/55, 9%), IGD (1/13, 7.7%). The diagnostic sensitivity of Floating Sign in morphea was 9%.

CONCLUSIONS

The Free Sign was present in most cases of morphea in our series and may represent a clue to the presence of evolving sclerosis. Free Sign may be seen in other sclerosing disorders. Technical artifact is a potential cause of a false-positive Free Sign.

Early Erythema Migrans: Do Not Count on Plasma Cells

ABSTRACT

Three hundred thousand new cases of Lyme disease are diagnosed annually in the United States. The earliest manifestation of the disease, erythema migrans, occurs earlier than serologic conversion, and skin biopsies can be very helpful in suggesting the diagnosis. Histopathologic findings vary depending on where in the lesion the specimen is taken, but typically consist of a superficial and deep perivascular and interstitial lymphocytic infiltrate with eosinophils centrally and with histiocytes and plasma cells at the periphery. Rare cases with interstitial histiocytes and rare-to-sparse plasma cells exist. We present a 67-year-old man whose skin biopsy, taken on day 2 of his eruption, demonstrated a subtle perivascular and interstitial infiltrate of histiocytes without plasma cells. Dermatopathologists need to be aware of this pattern and consider the diagnosis of erythema migrans, despite negative initial serologic testing.

[Granulomatous reaction pattern of the skin : Interstitial granulomatous dermatitis - lymphoma - vasculitis]

A particular diagnostic situation in the classification of a granulomatous dermatitis results when no circumscribed granulomas but instead a diffuse interstitial histiocytic inflammatory infiltrate, a granulomatous vasculitis or a neoplastic lymphocytic infiltrate is found. Interstitial granulomatous dermatitis was originally described in patients with arthritis. Later, it was recognized that there are also associations with other usually immunological diseases. Differentiating between interstitial granulomatous dermatitis and the interstitial form of granuloma annulare, early morphea and variants of borreliosis or scleromyxedema as well as interstitial granulomatous drug reaction can be very difficult. In long-standing cutaneous granulomatous infiltrates, T‑cell lymphoma should be excluded. Occasionally only a small number of atypical lymphocytes can be found. The detection of a monoclonal T‑cell expansion is then particularly helpful. Only recently, a CD8-positive granulomatous cutaneous T‑cell lymphoma was described which occurred in patients with immunodeficiencies. A granulomatous vasculitis in the skin is extremely rare. According to the Chapel Hill classification from 2012, systemic granulomatous vasculitis is equated with giant cell arteritis. Extracutaneous large arteries are involved. On rare occasions, involvement of the temporal artery can result in skin necrosis. More commonly granulomatous infiltrates in combination with vasculitis can be observed, whereby various infectious diseases, sarcoidosis and nodular vasculitis should be considered. Granulomatosis with polyangiitis (formerly Wegener's granulomatosis), presents in the skin as leukocytoclastic vasculitis. Here granulomas are extremely rare.

[Lyme nephritis in humans: Physio-pathological bases and spectrum of kidney lesions]

Known in less than half a century, borreliosis, or Lyme disease, is a zoonosis caused by the tick bite. It is the most common vector disease in Europe and the United States. Borrelia burgdorferi sensu lato, the bacterium in question, is fitted with a "cunning device" that allows it to trick the immune system and implant the infection chronically. It causes multi-system tissue damage mediated by the inflammatory response of the host. Renal involvement is rarely reported and is better known in dogs as Lyme nephritis. The first case of kidney impairment in the human being was described in 1999, and since then eight other cases have been reported. The involvement is preferentially glomerular; the histological forms vary between immune complex nephropathy and podocytopathy. The pathophysiological mechanisms appear to be triple: immune complex deposits, podocytic hyper-expression of the B7-1 membrane protein, and renal infiltration of inflammatory cells. On the basis of the accumulated knowledge of the disease in just over 40 years, this review aims at establishing the physio-pathological hypotheses of renal involvement in order to better define the histological lesions.

[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.

[Non-infectious granulomatous inflammation: Focus on the lungs and skin]

Whereas a granulomatous reaction represents a physiologically useful immune defense mechanism against many infections, in autoimmune diseases granuloma formation and the concomitant inflammatory mechanisms may provoke a potentially organ-threatening reaction. Morphologically, several defined sub-types of granuloma have long been known, e.g. foreign body granuloma, tuberculous granuloma,sarcoid, pseudosarcoid, rheumatoid and rheumatic fever granulomas. However, in practice, assigning granulomas to a certain etiology from a biopsy or resection specimen can be a challenging diagnostic process. This article gives a practically oriented overview of the clinically most relevant non-infectious granulomatous diseases. The etiology, epidemiology, clinical correlation and morphology of granulomatous diseases are discussed, focussing on the lungs and skin.

Progress in the molecular diagnosis of Lyme disease

INTRODUCTION

Current laboratory testing of Lyme borreliosis mostly relies on serological methods with known limitations. Diagnostic modalities enabling direct detection of pathogen at the onset of the clinical signs could overcome some of the limitations. Molecular methods detecting borrelial DNA seem to be the ideal solution, although there are some aspects that need to be considered. Areas covered: This review represent summary and discussion of the published data obtained from literature searches from PubMed and The National Library of Medicine (USA) together with our own experience on molecular diagnosis of Lyme disease. Expert commentary: Molecular methods are promising and currently serve as supporting diagnostic testing in Lyme borreliosis. Since the field of molecular diagnostics is under rapid development, molecular testing could become an important diagnostic modality.

Cordoniform morphea: a clinicopathologic study of two cases presenting with the rope sign

BACKGROUND

Morphea clinically presenting as cordoniform lesions has not been described previously in the literature.

OBJECTIVE

Our goal was to describe the clinicopathologic features of morphea presenting with cord-like cutaneous lesions.

METHODS

The clinical notes of 420 patients with a diagnosis of morphea seen during the previous 10 years were reviewed to identify any cases that had cordoniform lesions at presentation.

RESULTS

Two adult patients (one male and one female) were identified. Both patients presented with chronic, slightly burning, bilateral, erythematous, linear or curvilinear elevated cutaneous indurations on the lateral chest wall strikingly reminiscent interstitial granulomatous dermatitis with arthritis. Histopathologically, typical changes of deep morphea with a band-like involvement only of the lower part of the reticular dermis and the superficial hypodermis and a remarkable perineural arrangement of the lymphoplasmocytic infiltrate were observed. The presence of Borrelia in skin biopsy samples of both patients was shown by immunohistochemistry and focus floating microscopy. In one patient, the presence of Borrelia afzelii DNA in the cutaneous biopsy was shown by polymerase chain reaction.

CONCLUSIONS

Cordoniform morphea is an exceedingly unusual and previously undescribed clinicopathologic presentation of morphea where Borrelia infection may play a causal role.

Histologic features of granulomatous skin diseases. Part 1: Non-infectious granulomatous disorders

Granulomatous disorders affecting the skin belong to a heterogeneous group of diseases. With the exception of granulomas induced by infectious agents or foreign bodies, the etiopathogenesis of granulomatous disorders is still poorly understood. The knowledge of histopathologic changes is of great importance for understanding clinical presentation and disease course.

Diagnostic approach in lymphoplasmacytic plaque

BACKGROUND

Lymphoplasmacytic plaque (LPP) is a recently described rare skin disease characterized by a dense dermal lymphohistiocytic infiltrate with polyclonal plasma cells. The clinical picture is distinct with reddish to brownish plaque with a predilection for the lower leg. LPP typically affects children.

OBJECTIVE

To define clinical and histologic criteria of LPP and to develop a diagnostic flow chart.

METHODS

We investigated six of our own LPP cases. Immunoglobulin light chains, IgG, IgG4, CD31, CD163 as a histiocytic marker were examined by immunohistochemistry. PCR-based molecular studies were conducted for borrelia sp., mycobacterial and leishmania sp. Moreover, 10 cases, which have been reported in the literature, were checked for the same features.

RESULTS

We could differentiate three main histological patterns (superficial band-like only, [deep] dermal only and mixed). Acanthosis and interface dermatitis are key features in cases with a superficial band-like or mixed infiltrate. Granulomas and giant cells could be only found in about 30% of the cases. The number of plasma cells was variable accounting for 5-40% of the infiltrate. The number of blood vessels was increased in the majority of the cases. 'Free-floating' collagen bundles surrounded by histiocytes (pseudorosettes) were identified as a new histological feature. An infectious agent could be excluded in all cases.

CONCLUSIONS

LPP is a long-standing skin disease, which may also occur in adults and in other body regions than the lower leg. Reproducible clinical and histological criteria allow delineating a diagnostic work-up for LPP.

Reactive Granulomatous Dermatitis: A Review of Palisaded Neutrophilic and Granulomatous Dermatitis, Interstitial Granulomatous Dermatitis, Interstitial Granulomatous Drug Reaction, and a Proposed Reclassification

The terms "palisaded neutrophilic and granulomatous dermatitis," "interstitial granulomatous dermatitis," and the subset "interstitial granulomatous drug reaction" are a source of confusion. There exists substantial overlap among the entities with few strict distinguishing features. We review the literature and highlight areas of distinction and overlap, and propose a streamlined diagnostic workup for patients presenting with this cutaneous reaction pattern. Because the systemic disease associations and requisite workup are similar, and the etiopathogenesis is poorly understood but likely similar among these entities, we propose the simplified unifying term "reactive granulomatous dermatitis" to encompass these entities.

Morphea and its variants and the "floating sign"-an additional finding in morphea

We report 2 patients with typical clinical findings of circumscribed morphea who on histopathologic examinations had histiocytes ("floating sign") surrounding individual collagen fibers in the dermis in addition to the key histologic findings of morphea. To our knowledge, there are no previous reports in the medical literature of such a phenomenon. Histopathological findings in idiopathic morphea and morphea-like conditions are reviewed.

A cutaneous interstitial granulomatous dermatitis-like eruption arising in myelodysplasia with leukemic progression

Cutaneous manifestations associated with myelodysplastic syndromes (MDS) are uncommon and can occur as specific or nonspecific lesions. Recognizing these cutaneous manifestations is important as they can precede blood or bone marrow transformation to leukemia. Granulomatous reactions have rarely been described as nonspecific lesions of MDS. These rare cases histologically resembled granuloma annulare, sarcoid, and a generalized dermal interstitial granulomatous dermatitis (IGD) which were not associated with leukemic infiltration. The authors report an interesting case of an IGD-like eruption evolving over the course of MDS with eventual progression to systemic leukemia. IGD is an inflammatory reaction that refers to a varied spectrum of histologic patterns and is associated with a variety of systemic illnesses and hypersensitivity reactions, including lymphoma and leukemia. In patients with MDS, surveillance for leukemia is a critical component of their follow-up care. Normally, this surveillance occurs through serial peripheral blood smears and bone marrow studies. IGD-like eruptions are a cutaneous reaction pattern that may serve as an additional clinical indicator of leukemic progression in patients with MDS. Although primarily a reactive pattern, this entity can rarely harbor leukemic blasts.

Damage of collagen and elastic fibres by borrelia burgdorferi - known and new clinical and histopathological aspects

Lyme Borreliosis, or Lyme's disease, manifests itself in numerous skin conditions. Therapeutic intervention should be initiated as soon as a clinical diagnosis of erythema migrans is made. The histopathology of some of the skin conditions associated with Lyme Borreliosis is characterised by structural changes to collagen, and sometimes also elastic fibres. These conditions include morphea, lichen sclerosus et atrophicus and acrodermatitis chronica atrophicans. More recently, further skin conditions have been identified by the new microscopic investigation technique of focus floating microscopy: granuloma annulare, necrobiosis lipoidica, necrobiotic xanthogranuloma, erythema annulare centrifugum, interstitial granulomatous dermatitis, cutaneous sarcoidosis and lymphocytic infiltration; these conditions also sometimes cause changes in the connective tissue. In the case of ligaments and tendons, collagen and elastic fibres predominate structurally. They are also the structures that are targeted by Borrelia. The resultant functional disorders have previously only rarely been associated with Borreliosis in clinical practice. Ligamentopathies and tendinopathies, spontaneous ruptures of tendons after slight strain, dislocation of vertebrae and an accumulation of prolapsed intervertebral discs as well as ossification of tendon insertions can be viewed in this light.

Borrelia and nephropathy: cryoglobulinaemic membranoproliferative glomerulonephritis responsive to doxycyclin in active Lyme disease

The association of membranoproliferative glomerulonephritis (MPGN) with Lyme borreliosis has only been reported for the C1q-negative subtype. A 64-year-old male presenting with rising creatinine, nephrotic syndrome and monoarthritis few months after a tick bite was noted to have mixed cryoglobulinaemia, a positive borrelia western blot and 'full-house' pattern MPGN with interstitial granuloma. Findings resolved with prednisolone and doxycyclin therapy. The histology is consistent with MPGN secondary to cryoglobulinaemia, which has most likely been caused by borrelia infection. 'Full-house' pattern MPGN may result from Lyme borreliosis through cryoglobulinaemia and may be treated successfully with the appropriate antibiotic therapy.

Presence of Borrelia burgdorferi "Sensu Lato" in patients with morphea from the Amazonic region in Brazil

BACKGROUND

In the present study, Borrelia spirochetes were found in four (26.6%) out of 15 patients with Atrophoderma of Pasini and Pierini (IAPP) and lichen sclerosis et atrophicans (LSA) from the Brazilian Amazon Region.

MATERIAL AND METHODS

Borreliosis was investigated by immunohistochemistry and focus floating microscopy for Borrelia burgdorferi in skin biopsy samples from 15 patients with both clinical and histopathology evidences compatible with Morphea, LSA, and IAPP.

RESULTS

Spirochetes were detected by specific immunohistochemistry and focus floating microscopy for B. burgdorferi in samples from three patients. A limitation of our study was the fact that we were not able to isolate and culture these organisms.

CONCLUSION

Our data confirm the presence of borreliosis cases in the Amazon.

Lyme borreliosis

Borreliosis is an infectious disease caused by spirochetes of the genus Borrelia. Lyme borreliosis, also known as Lyme disease, is a non-contagious infectious disease caused by spirochetes belonging to the complex Borrelia burgdorferi sensu lato and more often transmitted by the bite of infected ticks of the genus Ixodes.The disease is characterized by a varied clinical profile, which can trigger cutaneous, articular, neurological and cardiac manifestations.

Evaluation of skin thickness lesions in patients with Lyme disease measured by modified Rodnan total skin score

Recently, a possible etiological connection between infection with Borrelia burgdorferi and various skin lesions, including morphea and systemic sclerosis (SSc), has been discussed. The aim of our study was the evaluation of frequency of skin thickening typical of SSc or morphea in the group of patients with Lyme disease (LD) with frequent exposition to tick bites. The group consisted of 110 patients with LD frequently exposed to tick bites form the northeastern Poland, which is an endemic area for this disease. To measure the skin lesions, the modified Rodnan total skin score (RTSS) was used. In the analyzed group, no skin changes typical of morphea or skin thickening were found. According to RTSS, all patients scored 0 points. Raynaud's phenomenon in all patients was not found. The relationship between scleroderma or morphea and LD is still a matter of controversy. Described by some authors, cases with LD and scleroderma may be associated with co-existence of B. burgdorferi infection with autoimmune process.

Erythema migrans: a reassessment of diagnostic criteria for early cutaneous manifestations of borreliosis with particular emphasis on clonality investigations

BACKGROUND

Controversy exists about the relationship of borrelia infection with B-cell lymphomas because B-cell clonality has been identified in infiltrates that contained borrelia-specific DNA. Systematic clinicopathological, immunophenotypical and molecular pathological studies of early borreliosis are lacking.

OBJECTIVES

(i) To clarify whether clonal B-cell populations are present already in early borreliosis of the skin (erythema migrans); (ii) to re-evaluate clinicopathological, immunophenotypical and molecular pathological criteria for diagnosis of erythema migrans.

METHODS

Study of 34 patients with erythema migrans confirmed by polymerase chain reaction (PCR). Infiltrates were analysed by histopathological and immunohistochemical methods and multiplex PCR for clonal IgH rearrangements.

RESULTS

Erythema migrans shows a broad spectrum of changes including sparse infiltrates of T lymphocytes, dense interstitial granulomatous infiltrates (CD68+), and pseudolymphomatous patterns with germinal centre formation. There were accompanying epidermal changes in 59% of patients, and plasma cells were an inconsistent finding. B cells were few when infiltrates were sparse, but increased disproportionately when infiltrates were dense. IgH rearrangement studies revealed one pseudo-oligoclonal, three pseudoclonal and three clonal infiltrates. Pseudoclonality was encountered when infiltrates contained only few B lymphocytes.

CONCLUSIONS

Infiltrates in erythema migrans are dominated by T cells followed by CD68+ histiocytes and B lymphocytes. Plasma cells are an inconsistent finding. Pseudoclonality of IgH rearrangement is a result of infiltrates being sparse in B lymphocytes and represents a pitfall in molecular pathological diagnosis that can only be avoided by duplicate or triplicate tests. Incidental B-cell clonality may be encountered in patients with unequivocal erythema migrans and should not be interpreted as a malignant lymphomatous process induced by borrelia.

Aspects dermatologiques au cours de la maladie de Lyme

Lyme borreliosis is a tick-borne zoonosis due to bacterial infection by Borrelia (B.) burgdorferi sensu lato The disease presents differently in Europe or North America and may be called European borreliosis when acquired in Europe. Lyme borreliosis evolves in 3 stages. The main manifestations include cutaneous, neurological, and joint involvement. Erythema migrans (EM) is the most specific and most frequent finding in patients with Lyme borreliosis. It is the hallmark of early-localized borreliosis. EM is a slowly expanding red macula that occurs in about 60-80% of patients contracting Lyme borreliosis. Central clearing of the red patch can occur. It appears at the site of the tick bite, 7 to 20 days after the bite. Borrelial lymphocytoma (BL) occur rarely in patients with the early-disseminated stage of the disease. BL is a red or brown nodule or plaque located on the nipple, the earlobe, the scrotum, or the face. It should not be confused with cutaneous B-cell lymphoma. Acrodermatitis chronica atrophicans (ACA) is the cutaneous manifestation of late borreliosis. It starts as a violaceous patch, usually located on the extensor surface of a limb. Periarticular nodules and cords can also be present. Without treatment, it will evolve over weeks or months to the typical atrophic stage with extensive dermo-epidermal atrophy and visibility of superficial veins. Only these 3 manifestations are clearly related to an infection with B. burgdorferi. The relationship between infection with B. burgdorferi and other dermatoses, especially morphea, lichen sclerosus, and interstitial granulomatous dermatitis is still debated.

The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America

Evidence-based guidelines for the management of patients with Lyme disease, human granulocytic anaplasmosis (formerly known as human granulocytic ehrlichiosis), and babesiosis were prepared by an expert panel of the Infectious Diseases Society of America. These updated guidelines replace the previous treatment guidelines published in 2000 (Clin Infect Dis 2000; 31[Suppl 1]:1-14). The guidelines are intended for use by health care providers who care for patients who either have these infections or may be at risk for them. For each of these Ixodes tickborne infections, information is provided about prevention, epidemiology, clinical manifestations, diagnosis, and treatment. Tables list the doses and durations of antimicrobial therapy recommended for treatment and prevention of Lyme disease and provide a partial list of therapies to be avoided. A definition of post-Lyme disease syndrome is proposed.

A novel case of polyfibromatosis and interstitial granulomatous dermatitis with arthritis

Polyfibromatosis is a rare condition in which several cutaneous fibrotic conditions, such as Dupuytren's contracture, keloid formation, Peyronie's disease and plantar fibromatosis, may coexist. Interstitial granulomatous dermatitis with arthritis is also a rare condition characterized by arthritis and infiltrated rope-like lesions with granulomatous histologic features. We report a case of the simultaneous occurrence of both conditions in the same individual. To our knowledge, this has not been previously described. The clinical course has been slow, progressive, and recalcitrant to treatment.

Molecular diagnosis of infectious diseases in dermatology

The molecular diagnosis of infectious disease has been growing considerably over the past decade. Nucleic acid amplification techniques, such as polymerase chain reaction, ligase chain reaction, transcription-mediated amplification, and nucleic acid sequence-based amplification, provide highly accurate diagnosis of numerous bacterial, viral, fungal, and parasitic infections involved in a variety of dermatologic diseases. In addition, signal amplification with hybrid capture, branched-DNA assays, and in situ hybridization have been used to detect numerous viral pathogens with high degrees of sensitivity and specificity. New technology that involves the use of DNA and protein microarrays has also enabled the detection of a variety of genes and gene mutations. With time, these diagnostic assays are decreasing in cost, gaining approval of the U.S. Food and Drug Administration, and becoming easier and more efficient to use. In the future, these assays will be able to deliver rapid and accurate diagnosis of infectious diseases within a single clinic visit.

LEARNING OBJECTIVE

At the completion of this learning activity, participants should be familiar with molecular diagnosis of infectious diseases in dermatology.

PCR-DIG ELISA with biotinylated primers is unsuitable for use in whole blood samples from patients with brucellosis

In an attempt to avoid some of the inconveniences associated with conventional PCR, such as electrophoresis in ethidium bromide, we developed and analyzed the yield of a digoxigenin-based enzyme-linked immunosorbent PCR assay (PCR-DIG ELISA) for the detection of specific Brucella target DNA. During the DNA amplification process in healthy subjects and controls (Brucella abortus B-19) non-specific amplification of fragments was formed between genomic DNA and specific biotin-labeled primers. The labeled non-specific fragments bound to streptavidin-coated wells, saturating the solid phase streptavidin by biotin-streptavidin interaction. The formation of these non-specific PCR products was demonstrated by reduction in absorbance with hemin, a Taq polymerase inhibitor, and identified by use of a silver stained method which improves the sensitivity of nucleic acid visualization.

Arthropods in dermatology

Arthropods are important in medicine for a multitude of reasons. Their bites and stings may induce allergic reactions, ranging from annoying to life-threatening. Many arthropod products are also capable of inciting allergic responses in sensitized persons. In recent years, bites and stings have gained greater attention owing to increased concern about disease transmission. A common hypersensitivity response to arthropod bites, stings, and products is papular urticaria. This eruption occurs primarily in children, who eventually "outgrow" this disease, probably through desensitization after multiple arthropod exposures. Papular urticaria is most often caused by fleas or bedbugs, but virtually any arthropod is capable of inducing such a reaction. Two arthropod classes of medical importance are the Arachnida (spiders, scorpions, ticks, and mites) and the Insecta (lice, fleas, bedbugs, flies, bees, and ants). Animals in these two classes are probably responsible for more morbidity and mortality worldwide than are any other group of venomous creatures. In general, the diagnosis of arthropod bites and stings is dependent on maintenance of a high index of suspicion and familiarity with the arthropod fauna not only in one's region of practice, but also in the travel regions of one's patients. Learning objective At the completion of this learning activity, participants should be familiar with the clinical manifestations caused by a variety of arthropods as well as the treatment and possible sequelae of arthropod attacks.