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The bugs and insects we love to hate can cause a variety of diseases. Commonly skin rashes and bites are initial manifestations but there are a number of other manifestations.


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A histopathologic study of arthropod bite reactions in 20 patients highlights relevant adnexal involvement.

Department of Dermatology, Friedrich-Schiller-University, Jena, Germany.


J Cutan Pathol. 2009 Jan;36(1):26-33. Abstract quote

BACKGROUND: Insect bites produce diverse skin reactions. Although quite common, the histopathologic features of arthropod assaults have not ever been studied systemically.

MATERIALS AND METHODS: Twenty biopsies from cases, clinically diagnosed as arthropod bite reactions between January 2003 and June 2007 were reviewed retrospectively. The aim of the study was to verify as to whether reliable histopathologic criteria could be established based on the frequency of findings observed.

RESULTS: Epidermal spongiosis (present in 16 of 20 cases), in particular spongiosis of the infundibular epithelium and acrosyringia as well as eosinophilic spongiosis, emerge as relevant diagnostic clues. A moderately dense, superficial and deep infiltrate consisting mainly of lymphocytes and eosinophils was prevalent in the dermis, with eosinophils tending to interstitial and periadnexal distribution. Of note, 19 of 20 (95%) cases revealed periadnexal involvement, whereas 16 of 20 (80%) had the infiltrate extending particularly along the sweat ducts and the coiled glands. In three biopsies, concomitant involvement of sweat glands, hair follicles and sebaceous glands was noted.

CONCLUSION: A practical histopathologic algorithm of arthropod bite recognition is proposed. The involvement of the sweat glands in the pattern of arthropod bite reaction is suggested as a new reliable diagnostic clue.
Arthropods in dermatology.

Steen CJ, Carbonaro PA, Schwartz RA.
J Am Acad Dermatol. 2004 Jun;50(6):819-42. Abstract quote

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.

Avian Mite Bites Acquired From a New Source, Pet Gerbils: Report of 2 Cases and Review of the Literature


Arch Dermatol. 2001;137:167-170

Avian mite dermatitis, also known as gamasoidosis, acariasis, and fowl or bird mite dermatitis, has been reported from exposure to a variety of birds

Ornithonyssus sylviarum (the northern fowl mite) and Dermanyssus gallinae (the chicken mite) have been the most common mites identified

Clinical manifestations in humans include pruritic papules, vesicles, and dermatitis

Report of 2 patients with avian mite bites from different sources, O sylviarum and D gallinae, acquired not from birds but from infested pet gerbils


Nineteen documented cases of Loxosceles reclusa envenomation

Hunter H. Sams, etal.

J Am Acad Dermatol 2001;44:603-8. Abstract quote

Objective: Our purpose was to review documented Loxosceles reclusa (brown recluse spider) envenomations and to describe the natural history.

Methods: This article is a retrospective review of 19 documented cases seen in a university dermatology clinic. The study included the cases of 11 female and 8 male patients between the ages of 15 and 54 years with documented cases of brown recluse spider bite between 1987 and 1993. Rest, ice compresses, elevation, and prophylactic antibiotics were used in all cases. Fourteen patients received dapsone and 11 received nonsteroidal anti-inflammatory drugs. Two patients were hospitalized. A 3-point scale of cutaneous lesion severity was developed. Analysis of the association between maximum lesion severity (mild, moderate, severe) and time to complete healing or final evaluation was statistically significant (P < .001).

Results: All patients presented with localized erythema. Most bites were on the extremities (18/19; 95%). The most common presenting symptom was pain at the bite site (10/19; 53%). Eleven patients (58%) had skin necrosis; 32% of them had areas of necrosis larger than 1 cm2. Time to healing ranged from 5 days to more than 17 weeks (mean, 5.6 weeks). Average time to healing for grade 3 (severe) lesions was 74 days, for grade 2 (moderate) lesions 22 days, and for grade 1 (mild) lesions 8 days (in patients seen more than once).

Conclusions: Brown recluse spider bites frequently induce necrotic, slowly healing lesions. Maximum lesion severity is a predictor of time to complete healing.


Ghost anemone dermatitis.

Freudenthal AR, Barbagallo JS.

Office of Marine Ecology, Nassau County Department of Health, Mineola; and Department of Dermatology, St. Luke's-Roosevelt Hospital Center, New York.

J Am Acad Dermatol 2002 Nov;47(5):722-6 Abstract quote

BACKGROUND: Haloclava producta, the "ghost anemone", is a burrowing sea anemone in estuarine sediments of the US East Coast and Gulf of Mexico. It has never been identified as harmful to human beings; however, residents of Long Island, New York develop a pruritic, erythematous, vesiculopapular dermatitis on areas of the body that contact these organisms. Neither the condition nor its cause has been described in the medical literature.

METHODS: We reviewed information of all water-related dermatitis reported by beach personnel, health providers, and affected swimmers to the Office of Marine Ecology, Nassau County Department of Health, New York from 1970 to 1991. Several episodes of an unfamiliar dermatitis among clam diggers, first recognized in 1981, initiated sampling efforts in 1985 when one victim, a bay constable, identified the area he frequented. During 1991, >100 persons were affected; sampling continued during reported cases. H. producta was isolated from all suspect sediment samples and tested on healthy subjects.

RESULTS: Typical of the phylum Cnidaria, H. producta has nematocysts capable of inflicting the observed dermatitis. Pressing them to the skin of healthy subjects produces dermatitis indistinguishable from that of victims. No other species with the same capability were identified from samples.

CONCLUSION: H. producta is the apparent causative agent of ghost anemone dermatitis. Accurate diagnosis will allow appropriate treatment, education regarding prevention, and avoidance of unnecessary diagnostic tests or antibiotic use.

Head lice: scientific assessment of the nit sheath with clinical ramifications and therapeutic options.

Burkhart CN, Burkhart CG.

University of North Carolina at Chapel Hill, North Carolina, USA.
J Am Acad Dermatol. 2005 Jul;53(1):129-33. Abstract quote  

Head lice, like many insects, produce a protective coating for their newly laid eggs that is essential to the survival of the species. Knowledge of the composition of the sheath, which is the glue by which the egg is attached to human hair, and the nit laying process could lead to production of agents that could be used to attack louse infestations by interfering with the normally protected environment of nymph development within the egg.

The physical removal of nits has become an important part of treatment of head louse infestations given the "no-nit" policy in schools. Biochemical analysis has revealed that the nit sheath of the head louse is composed of 4 bands of protein, possibly cross-linked to aliphatic components with a tertiary structure of beta sheeting. Nature has protected the louse by making the nit sheath similar in composition to the hair; thereby, agents designed to unravel the nit sheath may also damage human hair.

Possible targets to destroy the nit sheath include proteases, denaturants, beta sheet breaker proteins, and small protein inhibitors of sheath formation. Better understanding of insect glues may allow us to develop compounds so that the liquid secretions of the collateral glands of the female louse, which becomes the nit sheath, do not solidify by oxidation when placed with the louse egg onto human hair.

Knowledge of insect behavior, such as oviposition, may also suggest methods for repelling female lice from laying eggs onto hair. Alternatively, agents that coat the nits and restrict the oxygen transfer to the developing larvae may prove beneficial.

One Linuche mystery solved: All 3 stages of the coronate scyphomedusa Linuche unguiculata cause seabather's eruption

Lourdes Segura-Puertas, etal.

J Am Acad Dermatol 2001;44:624-8 Abstract quote

Background: Seabather's eruption (SBE) is a highly pruritic dermatosis affecting swimmers and divers in marine waters off Florida, in the Gulf of Mexico, and the Caribbean Sea. Its cause has been attributed to various organisms but recently to the larvae of the schyphomedusa, Linuche unguiculata.

Objective: We attempted to determine whether immature and adult Linuche cause SBE.

Methods: Episodes of SBE in the Cancun and Cozumel area of the Mexican Caribbean were evaluated during the season of high tourism (January-June). This time corresponds to the moments in the life cycle when the three swimming stages of L unguiculata—ephyrae, medusae, and larvae—can be sequentially observed. Our methods include (1) observations by divers, biologists, and students coinciding with stinging outbreaks and the onset of SBE; (2) serologic evaluation of individuals stung by L unguiculata; and (3) the demonstration of Linuche nematocysts on the affected skin.

Results: All 3 swimming Linuche stages can cause SBE.

Conclusion: The offending stages of Linuche can be identified by the cutaneous lesion's morphology and the time of year.


CD4+ T-lymphocyte-induced Epstein-Barr virus reactivation in a patient with severe hypersensitivity to mosquito bites and Epstein-Barr virus-infected NK cell lymphocytosis.

Asada H, Miyagawa S, Sumikawa Y, Yamaguchi Y, Itami S, Suguri S, Harada M, Tokura Y, Ishihara S, Ohshima S, Yoshikawa K.

Department of Dermatology, Nara Medical University, Kashihara, Japan.
Arch Dermatol. 2003 Dec;139(12):1601-7. Abstract quote  

BACKGROUND: Natural killer (NK) cell lymphocytosis associated with Epstein-Barr virus (EBV) infection often shows severe hypersensitivity to mosquito bites (HMB) characterized by intense local skin reactions and systemic symptoms such as high fever, lymphadenopathy, and hepatosplenomegaly. However, the induction mechanism of HMB is still unclear.

OBSERVATIONS: We investigated a typical case of HMB with EBV-positive NK cell lymphocytosis. CD4+ T cells dominantly infiltrated the site of the mosquito bite, while EBV-positive cells were few in comparison. CD4+ T cells, but not CD8+ T cells or NK cells, responded to the mosquito salivary gland extracts. Interestingly, coculturing of the NK cells and CD4+ T cells activated by mosquito extracts induced expression of EBV lytic-cycle proteins in the NK cells. Furthermore, the expression of BZLF1, a viral lytic-cycle transactivator, was detectable at the skin lesion induced by scratch patch testing with mosquito extract. The EBV DNA copy number levels in the plasma were elevated in systemic HMB symptoms compared with the normal condition.

CONCLUSIONS: CD4+ T cells are important for the primary skin reaction to mosquito bites and might play a key role in reactivation of latent EBV infection in NK cells. This viral reactivation contributed to the pathogenesis of the infectious mononucleosis-like systemic symptoms of HMB in our present case.

Hypersensitivity to mosquito bites as the primary clinical manifestation of a juvenile type of Epstein-Barr virus-associated natural killer cell leukemia/lymphoma

Yoshiki Tokura, MD
Shigehiko Ishihara, MD
Shinichi Tagawa, MD
Naohiro Seo, PhD
Kouichi Ohshima, MD
Masahiro Takigawa, MD

Hamamatsu, Kashiwara, Osaka, and Fukuoka, Japan

J Am Acad Dermatol 2001;45:569-78 Abstract quote

Hypersensitivity to mosquito bites or mosquito allergy is a mysterious disorder that has been reported mainly in Japanese patients (at least 58 patients) in the first two decades of life. The skin lesion at bite sites is typically a bulla that develops into necrosis. Patients simultaneously exhibit a high temperature and general malaise and subsequently may experience lymphadenopathy and hepatosplenomegaly.

Recent studies have revealed that this mosquito hypersensitivity is associated with chronic Epstein-Barr virus infection and natural killer cell leukemia/lymphoma. The natural killer cell, infected with monoclonal (or oligoclonal) Epstein-Barr virus, seems to be involved in the pathogenesis of the hypersensitivity. Half of the patients reported died of hemophagocytic syndrome (or malignant histiocytosis), granular lymphocyte proliferative disorder, or lymphomas.

We propose that this disease, defined as the triad of hypersensitivity to mosquito bites, chronic Epstein-Barr virus infection, and natural killer cell leukemia/lymphoma, is a clinical entity mostly seen in Asians.

Cutaneous myiasis.

Department of Preventive Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.

J Am Acad Dermatol. 2008 Jun;58(6):907-26; Abstract quote

Myiasis is the infestation of living tissue by the larvae of flies in the order Diptera. Cutaneous involvement is the most common type of myiasis. Cutaneous myiasis can be subdivided into furuncular, migratory, and wound myiasis. Each subtype is reviewed with discussion of the larvae involved, presenting signs and symptoms, clinical differential diagnoses, and treatment. Preventive measures are also described.

LEARNING OBJECTIVES: At the conclusion of this learning activity, participants should be familiar with the causal agents, clinical manifestations, and treatment of human cutaneous myiasis.
Local reactions to tick bites.

Department of Dermatology, University of Palermo, Palermo, Italy.

Am J Dermatopathol. 2008 Jun;30(3):241-8. Abstract quote

A retrospective histological and immunohistochemical study has been carried out in 25 cases of tick bites recorded in our Departments. The samples that included an attached tick showed a cement cone anchoring the mouthparts to the skin and a blood-soaked, spongiform appearance of the superficial dermis, with a mild neutrophilic and eosinophilic infiltration. The vessels displayed a loose multilayered endothelial proliferation, with plump endothelia, permeated with erythrocytes. A few of them were severed, allowing copious blood extravasation.

The established lesions included the following: erythema chronicum migrans-like cases, foreign body granulomas-sometimes containing remnants of the mouthparts-cutaneous lymphoid hyperplasia, either of the T-cell or the B-cell type, and tick-bite alopecia. In both the T-cell and B-cell pseudolymphomas, several vessels showed concentric endothelial and perithelial proliferation similar to that seen in the acute lesions. In the tick-bite alopecia, a lymphocytic infiltrate attacked the permanent portion of the hair follicles, whose reaction was a noticeable hyperplasia of the fibrous sheaths, although only a minority of the hairs was destroyed.

The observed alterations are specific in the acute lesions and in the alopecia, where they directly arise as a result of the interactions between the host's tissues and the antihemostatic, anti-inflammatory, and immunomodulatory chemicals contained in the tick saliva. In the other lesions, the changes seem less characteristic, although the fragments of mouthparts and the special vascular changes provide a clue to their etiology.
Multiple pruritic papules from lone star tick larvae bites.

Fisher EJ, Mo J, Lucky AW.

Division of Pediatric Dermatology and Department of Pathology, Cincinnati Children's Hospital Medical Center, OH 45267, USA.
Arch Dermatol. 2006 Apr;142(4):491-4. Abstract quote  

BACKGROUND: Ticks are the second most common vectors of human infectious diseases in the world. In addition to their role as vectors, ticks and their larvae can also produce primary skin manifestations. Infestation by the larvae of ticks is not commonly recognized, with only 3 cases reported in the literature. The presence of multiple lesions and partially burrowed 6-legged tick larvae can present a diagnostic challenge for clinicians.

OBSERVATION: We describe a 51-year-old healthy woman who presented to our clinic with multiple erythematous papules and partially burrowed organisms 5 days after exposure to a wooded area in southern Kentucky. She was treated with permethrin cream and the lesions resolved over the following 3 weeks without sequelae. The organism was later identified as the larva of Amblyomma species, the lone star tick.

CONCLUSIONS: Multiple pruritic papules can pose a diagnostic challenge. The patient described herein had an unusually large number of pruritic papules as well as tick larvae present on her skin. Recognition of lone star tick larvae as a cause of multiple bites may be helpful in similar cases.

Dermatoses from ticks.

McGinley-Smith DE, Tsao SS.

Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA.

J Am Acad Dermatol. 2003 Sep;49(3):363-92; Abstract quote  

Ticks are ectoparasites that cause dermatologic disease directly by their bite and indirectly as vectors of bacterial, rickettsial, protozoal, and viral diseases. In North America, where ticks are the leading cause of vector-borne infection, dermatologists should recognize several tick species. Basic tick biology and identification will be reviewed.

Tick bites cause a variety of acute and chronic skin lesions. The tick-borne diseases include Lyme disease, tick-borne relapsing fever, tularemia, babesiosis, Rocky Mountain spotted fever, other spotted fevers, ehrlichiosis, Colorado tick fever, and others.

The epidemiology, clinical features, diagnosis, and treatment of these diseases are reviewed with an emphasis on cutaneous manifestations. Finally, the prevention of diseases caused by ticks is reviewed.

Tick mouth parts occlusive vasculopathy: a localized cryoglobulinemic vasculitic response.

Galaria NA, Chaudhary O, Magro CM.

Department of Dermatology, Strong Memorial Hospital, Rochester, NY, USA, Medical School, University of Western Ontario, London, Ontario, Canada, and Department of Pathology, Ohio State University, OH, USA.

J Cutan Pathol. 2003 May;30(5):303-6. Abstract quote

BACKGROUND: The histologic hallmark of most arthropod bite reactions is a deep, wedge-shaped perivascular and interstitial infiltrate comprising lymphocytes, neutrophils, and eosinophils.

METHODS: We present a case series of six patients in whom tick bite reactions, when examined microscopically, were found to mimic mixed cryoglobulinemic vasculitis.

RESULTS: Though different in histology, clinically these lesions were indistinguishable from typical tick bite reactions.

CONCLUSION: As five of our six biopsy specimens were found to still harbor retained tick parts, it is possible that the actual retention of tick parts was involved in evoking this localized cryoprecipitate reaction.

Type-I cryoglobulinemia-like histopathologic changes in tick bites: a useful clue for tissue diagnosis in the absence of tick parts

Catherine M. Stefanato
Robert G. Phelps
Lynne J. Goldberg
Ann E. Perry
and Jag Bhawan
J Cutan Pathol 2002;29:101-106 Abstract quote

Background:The histopathologic findings of localized reactions to tick bites may present as diagnostic dilemmas, especially if there is no history of a tick bite, or if the tick's mouthparts are not present in the biopsied skin.

Objective:Skin biopsies of patients with a clinical history of a tick bite were selected and reviewed with the aim of detecting a common histopathologic denominator which could serve as a useful clue to the diagnosis, especially when the tick's mouthparts are absent.

Methods:Hematoxylin and eosin-stained slides of 15 skin biopsies of tick bites were retrieved from three dermatopathology and pathology laboratories. Where additional paraffin-embedded tissue was available, additional sections were also stained with periodic acid-Schiff (PAS) and phosphotungstic acid-hematoxylin (PTAH).

Results:In every case in which adequate tissue was available (13/15 biopsies), the capillaries and postcapillary venules of the superficial and deep vascular plexi adjacent to the attachment's site were filled with thrombi. Fibrin thrombi were seen in association with other more numerous thrombi characterized by homogeneous eosinophilic hyaline material similar to the cryoprecipitate present in type I (monoclonal) cryoglobulinemia. All thrombi were positive for PAS and PTAH; however, the latter staining was minimally present in the hyaline thrombi. In most cases, the site of the tick bite showed ulceration, with an underlying wedge-shaped superficial and deep perivascular and occasionally interstitial mixed lymphohistiocytic infiltrate. In addition, there were eosinophils, numerous neutrophils and extravasated erythrocytes. Other findings included suppurative necrosis (7/15) cases, giant-cell reaction (one case), fat necrosis (one case) and eccrine gland necrosis (one case).

Conclusions:Vascular eosinophilic hyaline thrombi were found to be a frequent histologic manifestation of a tick bite. This finding may be related to the secretory products of the tick's saliva during inoculation. We believe that a tick bite should be suspected when focal intravascular hyaline occlusion is observed, and that it should be included in the differential diagnosis of type I (monoclonal) cryoglobulinemia, even if there is no history of a tick bite or if tick parts are not present in the skin biopsy specimen.


Typical Histologic Features of Tunga penetrans in Skin Biopsies.

Smith MD, Procop GW.

Division of Pathology and Laboratory Medicine, The Cleveland Clinic Foundation, Cleveland, Ohio.

Arch Pathol Lab Med 2002 Jun;126(6):714-6 Abstract quote

Context.-Tunga penetrans is a flea that burrows into human skin, causing the disease tungiasis. Although the parasite is not endemic in the United States, patients may present with this disease upon returning from tropical locales. Histologic sections contain a variety of flea parts that may present a diagnostic dilemma for pathologists unfamiliar with this disease.

Objective.-To determine the typical histologic features of T penetrans in biopsies from patients with tungiasis.

Methods.-We reviewed biopsy specimens from 7 patients with tungiasis and sought 8 distinct structures: the exoskeleton, hypodermal layer, respiratory tract (tracheae), digestive tract, striated muscle, head, posterior end, and developing eggs.

Results.-The exoskeleton, hypodermal layer, tracheae, digestive tract, and developing eggs were present in all biopsy specimens reviewed. Striated muscle, the posterior end, and head, however, were present in 57%, 43%, and 0% of the biopsies, respectively. In addition, we noted a unique, pale-staining layer in the exoskeleton at the posterior end of the organism that, to the best of our knowledge, has not previously been described and that may be of diagnostic value.

Conclusions.-Despite the absence of 3 key morphologic features in many (posterior end and striated muscle) or all (head) of our biopsies, the exoskeleton with a hypodermal layer, tracheae, and developing eggs were uniformly present, and together these features are sufficient for a diagnosis of tungiasis.

Bacterial superinfection in human tungiasis.

Feldmeier H, Heukelbach J, Eisele M, Sousa AQ, Barbosa LM, Carvalho CB.

Institute of Social Medicine, Center for Humanities and Health Sciences, Faculty of Medicine, Free University of Berlin, Germany, Mandacaru Foundation, Fortaleza, Brazil, Ceara State Ministry of Health, Fortaleza, Brazil, Department of Microbiology, Faculty of Medicine, Federal University of Ceara, Fortaleza, Brazil.

Trop Med Int Health 2002 Jul;7(7):559-564 Abstract quote

Tungiasis is caused by penetration of the female sand flea Tunga penetrans into the epidermis of its host. It is endemic in many countries in Latin America, the Caribbean and sub-Saharan Africa. Although superinfection is a common clinical observation, the frequency and the pattern of bacterial pathogens associated with tungiasis have never been investigated systematically.

We conducted a prospective clinico-bacteriological study with patients living in a shantytown in Fortaleza, capital of Ceara State (Northeast Brazil), where tungiasis is hyperendemic. Swabs were taken from 78 patients with multiple lesions after surgical extraction of the parasite, and the specimens were cultured for aerobic and anaerobic microorganisms. Ninety-nine specimens were investigated for aerobic bacteria, from which 146 pathogens were identified. The most common species were Staphyloccous aureus (35.5%) and various enterobacteriaceae (29.5%). Bacillus sp., Enteroccous faecalis, Streptococcus pyogenes and Pseudomonas sp. were also isolated. Eighty-four anaerobic cultures yielded 20 pathogens: in eight cases we detected Peptostreptococcus sp., in seven cases Clostridium sp., and in five cases non-identifiable gram-negative bacilli. These results show that secondary infection is very common in tungiasis, and caused by a variety of highly pathogenic microorganisms.

It is proposed that T. penetrans acts as a foreign body facilitating biofilm formation within the epidermis. To prevent spreading of pathogens to the surrounding tissue and/or the systemic circulation, sand fleas should be surgically extracted immediately after penetration.

A scanning microscopic clue to the diagnosis of arthropod assault reaction: alteration of interstitial tissue is more common than a wedge-shaped inflammatory infiltrate.

Institut für Dermatohistologie, Heidelberg, Germany.


J Cutan Pathol. 2009 Mar;36(3):308-13. Abstract quote

BACKGROUND: A scanning microscopic clue to the diagnosis of arthropod assault reactions is a wedge-shaped inflammatory infiltrate. However, to describe an inflammatory infiltrate as wedge-shaped or not involves a high degree of subjectivity.

METHODS: We studied hematoxylin and eosin-stained sections of 137 biopsies of arthropod assault reactions for epidermal and dermal changes and for the composition, density and depth of the inflammatory infiltrate.

RESULTS: We found a wedge-shaped inflammatory component in only 10.2% of the cases. A much more common feature is an alteration of the interstitial tissue present in 85.4% of the biopsies. It consisted of a narrowing of the spaces between the collagen bundles, which was readily observable on scanning magnification. On higher magnification, a loosely textured basophilic material was often noted within the dermis.

CONCLUSIONS: The hitherto often emphasized wedge-shaped configuration of the inflammatory component of arthropod assault reactions is not of great diagnostic value. The altered interstitial tissue is easily recognizable by its diminished interstitial spaces at low power magnification and can serve as a scanning magnification clue to the diagnosis of arthropod assault reactions.

Prominent Langerhans' cell migration in the arthropod bite reactions simulating Langerhans' cell histiocytosis.

Department of Pathology, College of Medicine, Yonsei University, Seoul, Korea.


J Cutan Pathol. 2007 Dec;34(12):899-902. Abstract quote

Background: Epidermal Langerhans' cells (LCs) play pivotal roles in cutaneous immune responses. An encounter with antigens or other stimuli causes the mobilization and migration of LCs. Therefore, some dermatoses, which originated from antigenic stimuli or trauma, can show LC migration. Recently, we experienced several cases of anthropod bites that showed marked inflammatory infiltrates with eosinophils and CD1a-positive LCs. It was difficult to differentiate these cases from Langerhans' cell histiocytosis (LCH).

Methods: The degree and pattern of LC infiltration in the skin of arthropod bite reaction was evaluated. The characteristics of CD1a immunohistochemical expression in the arthropod bite reactions were compared with those of LCH.

Results: A few arthropod bite cases (approximately 36%) showed extensive CD1a-positive LCs in the dermis, especially in the perivascular area. In addition, the CD1a expression patterns of LCs in the arthropod bite reactions were dendritic, whereas that of tumor cells in LCH were distinctly membranous and cytoplasmic.

Conclusion: Some arthropod bite reactions can show marked CD1a-positive LCs in the dermis, especially in the perivascular area. The dendritic CD1a immunohistochemical staining pattern in arthropod bite reactions is useful in helping to differentiate from LCH.
Insect Bite-Like Reaction Associated With Mantle Cell Lymphoma: Clinicopathological, Immunopathological, and Molecular Studies.

Khamaysi Z, Dodiuk-Gad RP, Weltfriend S, Ben-Arieh Y, Dann EJ, Sahar D, Bergman R.

From the *Department of Dermatology, daggerDepartment of Pathology, double daggerDepartment of Hematology, and section signMolecular Hematology Laboratory, Rambam Medical Center and the Bruce Rappaport Faculty of Medicine, Haifa, Israel.
Am J Dermatopathol. 2005 Aug;27(4):290-295. Abstract quote  

A cutaneous eruption simulating insect bites has been repeatedly described in association with chronic lymphocytic leukemia (CLL). It was only rarely described with mantle cell lymphoma (MCL).

Our study was performed to elucidate the clinical, histologic, immunopathological, and molecular characteristics of insect bite like reaction (IBLR) associated with MCL. The clinical presentation and histologic findings in 3 IBLR cases associated with MCL were found to be similar to 3 IBLR cases associated with CLL. The eruptions consisted of itchy erythematous papules, nodules, plaques, and vesicles. Non-vesicular lesions were characterized histologically by normal or mildly spongiotic epidermis. Vesicular lesions were characterized by marked spongiosis and intraepidermal spongiotic vesicles containing eosinophils, or marked subepidermal edema occasionally leading to a dermoepidermal separation. Most of the lesions were characterized by superficial and mid dermal to deep perivascular and interstitial, and occasionally periadnexal, inflammatory-cell infiltrate consisting of mononuclear cells and eosinophils. The densities of the infiltrates varied and the inflammatory-cell infiltrate extended often into the fat lobules.

Neutrophils and nuclear dust were found more frequently and abundantly in the IBLR lesions associated with MCL. Immunophenotyping, direct immunofluorescence (DIF) tests, and IgH gene rearrangement studies were performed in the lesions associated with MCL only. The majority of the infiltrating lymphocytes were CD3+, CD5+ and CD43+, more CD4+ than CD8+, and only a small minority was CD20+. The cells did not stain for bcl-1 protein and CD30, and with no evidence of clonality. The DIF test result was negative.

The IBLR eruption associated with MCL resembles clinically and histologically IBLR associated with CLL. The eruption seems to be reactive rather than neoplastic, because there is no evidence of MCL involvement in the skin lesions.



Comparative efficacy of insect repellents against mosquito bites.

Fradin MS, Day JF.

Chapel Hill Dermatology, Chapel Hill, NC 27514, USA.

N Engl J Med 2002 Jul 4;347(1):13-8 Abstract quote

BACKGROUND: The worldwide threat of arthropod-transmitted diseases, with their associated morbidity and mortality, underscores the need for effective insect repellents. Multiple chemical, botanical, and "alternative" repellent products are marketed to consumers. We sought to determine which products available in the United States provide reliable and prolonged complete protection from mosquito bites.

METHODS: We conducted studies involving 15 volunteers to test the relative efficacy of seven botanical insect repellents; four products containing N,N-diethyl-m-toluamide, now called N,N-diethyl-3-methylbenzamide (DEET); a repellent containing IR3535 (ethyl butylacetylaminopropionate); three repellent-impregnated wristbands; and a moisturizer that is commonly claimed to have repellent effects. These products were tested in a controlled laboratory environment in which the species of the mosquitoes, their age, their degree of hunger, the humidity, the temperature, and the light-dark cycle were all kept constant.

RESULTS: DEET-based products provided complete protection for the longest duration. Higher concentrations of DEET provided longer-lasting protection. A formulation containing 23.8 percent DEET had a mean complete-protection time of 301.5 minutes. A soybean-oil-based repellent protected against mosquito bites for an average of 94.6 minutes. The IR3535-based repellent protected for an average of 22.9 minutes. All other botanical repellents we tested provided protection for a mean duration of less than 20 minutes. Repellent-impregnated wristbands offered no protection.

CONCLUSIONS: Currently available non-DEET repellents do not provide protection for durations similar to those of DEET-based repellents and cannot be relied on to provide prolonged protection in environments where mosquito-borne diseases are a substantial threat.

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