Nineteen documented cases of Loxosceles reclusa envenomation

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 cm(2). 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.

Necrotic arachnidism

Necrotic arachnidism is the potential cutaneous reaction to spider bite venom. In the United States, members of 7 spider families may be responsible for envenomation sufficiently severe to warrant treatment. Characteristics of several spiders, in particular Loxosceles spiders, whose bite is toxic to humans are described, and diagnostic standards, preventive measures, and treatment options are reviewed. (J Am Acad Dermatol 2001;44:561-73.)

LEARNING OBJECTIVE

After the completion of this learning activity, participants should be familiar with the characteristics of several different spider families endemic to the United States. Furthermore, this learning activity should aid in the prevention and diagnosis of spider bites as well as in the classification and treatment of specific bites.

Middermal elastolysis in two patients with lupus erythematosus

Despite lupus erythematosus (LE) being considered a "connective tissue disease," little has been written about the elastic fiber changes in the skin of affected patients. We report our histologic findings in two patients with unusual cutaneous lesions. Elastic fiber loss was noted, and scattered giant cells with elastic fiber phagocytosis were prominent in one patient. The findings are similar to those described for middermal elastolysis. Other authors have reported patients with LE and elastic fiber loss resembling anetoderma. We believe that a spectrum of elastic fiber changes can occur in patients with LE and may be induced by infiltrating lymphocytes and/or circulating antibodies.

Comparison of alopecia areata in human and nonhuman mammalian species

Alopecia areata (AA) is a nonscarring form of inflammatory hair loss in humans. AA-like hair loss has also been observed in other species. In recent years the Dundee experimental bald rat and the C3H/HeJ mouse have been put forward as models for human AA. AA in all species presents with a wide range of clinical features from focal, locally extensive, diffuse hair loss, to near universal alopecia. Histologically, all species have dystrophic anagen stage hair follicles associated with a peri- and intrafollicular inflammatory cell infiltrate. Autoantibodies directed against anagen stage hair follicle structures are a consistent finding. Observations on AA pathogenesis suggest nonhuman species can provide excellent models for the human disease. Ultimately, animal models will be used to determine the genetic basis of AA, potential endogenous and/or environmental trigger(s), mechanism(s) of disease initiation and progression, and allow rapid evaluation of new and improved disease treatments.

Variations in the cell cycle status of lymphopoietic and myelopoietic cells created by zinc deficiency

Zinc deficiency causes thymic atrophy and lymphopenia. It was recently shown that zinc deficiency causes sizable losses among the precursor lymphocytes, such that this compartment was depleted 40%-50% in the marrow of young adult mice. However, the myeloid compartments increased substantially both in proportion and absolute number as zinc deficiency advanced. Zinc deficiency caused no change in the cell cycle status of precursor B cells and only modest changes in cycling pro-B cells. Conversely, cells of the myeloid series, especially monocytes, exhibited as much as a 40% increase in the proportion of cells in S and G(2)/M, while myeloid progenitors had an overall 56% increase in cells in the proliferative phase as zinc deficiency advanced. Whether zinc deficiency alters the rate of production of myeloid and lymphopoietic cells or alters the degree of apoptosis or both awaits further study.

Mercury exposure and cutaneous disease

Human contact with mercury has been ongoing for centuries and was previously considered a legitimate means of treating different cutaneous and systemic conditions. Toxicity from this heavy metal may occur from exposure to elemental, inorganic, and organic forms of mercury. This article outlines the signs and symptoms of mercury poisoning and the different clinical conditions with assorted cutaneous findings.

Lanceolate hair-J (lahJ): a mouse model for human hair disorders

Lanceolate hair-J (lahJ) arose spontaneously in 1994 on the DBA/1LacJ inbred background at The Jackson Laboratory. Mutant mice were runted, alopecic, and lacked vibrissae. As they aged, their skin wrinkled. Affected mice developed a noninflammatory, proliferative skin disease with follicular dystrophy. Hair fibers developed a number of abnormalities including periodic nodules along the shaft (trichorrhexis nodosa), compaction resembling trichorrhexis invaginata, spiral fractures, broken tips, and lance-shaped tips. This mutation exhibits some characteristics that resemble an autosomal recessive ichthyosiform disease that occurs in humans characterized in part by peculiar, invaginating, multinodal, hair shaft abnormalities known as Netherton's syndrome. Periodic nodules also resemble the human genetic based disease monilethrix. This autosomal recessive mouse mutation, allelic with lanceolate hair (lah), based on breeding studies, is located on mouse Chromosome 18, within a cluster of genes coding for adhesion molecules. Homozygotes for either of these allelic mouse mutations have elevated serum IgE levels, a feature also common with human Netherton's syndrome.

The dynamic link between the integrity of the immune system and zinc status

The results of more than three decades of work indicate that zinc deficiency rapidly diminishes antibody- and cell-mediated responses in both humans and animals. The moderate deficiencies in zinc noted in sickle cell anemia, renal disease, chronic gastrointestinal disorders and acrodermatitis enteropathica; subjects with human immunodeficiency virus; children with diarrhea; and elderly persons can greatly alter host defense systems, leading to increases in opportunistic infections and mortality rates. Conversely, short periods of zinc supplementation substantially improve immune defense in individuals with these diseases. Mouse models demonstrate that 30 d of suboptimal intake of zinc can lead to 30-80% losses in defense capacity. Collectively, the data clearly demonstrate that immune integrity is tightly linked to zinc status. Lymphopenia and thymic atrophy, which were the early hallmarks of zinc deficiency, are now known to be due to high losses of precursor T and B cells in the bone marrow. This ultimately leads to lymphopenia or a failure to replenish the lymphocytic system. Glucocorticoid-mediated apoptosis induced by zinc deficiency causes down-regulation of lymphopoiesis. Indeed, zinc itself can modulate death processes in precursor lymphocytes. Finally, there is substantial evidence that zinc supplementation may well reduce the impact of many of the aforementioned diseases by preventing the dismantling of the immune system. The latter represents an important area for research.

Massive xanthomatosis and altered composition of atherosclerotic lesions in hyperlipidemic mice lacking acyl CoA:cholesterol acyltransferase 1

Inhibitors of acyl CoA:cholesterol acyltransferase (ACAT) have attracted considerable interest as a potential treatment for atherosclerosis. Currently available inhibitors probably act nonselectively against the two known ACATs. One of these enzymes, ACAT1, is highly expressed in macrophages in atherosclerotic lesions, where it contributes to foam-cell formation. In this study, we examined the effects of selective ACAT1 deficiency in two mouse models of atherosclerosis. In the setting of severe hypercholesterolemia caused by deficiency in apoE or the LDL receptor (LDLR), total ACAT1 deficiency led to marked alterations in cholesterol homeostasis and extensive deposition of unesterified cholesterol in the skin and brain. Bone marrow transplantation experiments demonstrated that ACAT1 deficiency in macrophages was sufficient to cause dermal xanthomas in hyperlipidemic LDLR-deficient mice. ACAT1 deficiency did not prevent the development of atherosclerotic lesions in either apoE-deficient or LDLR-deficient mice, despite causing relatively lower serum cholesterol levels. However, the lesions in ACAT1-deficient mice were atypical in composition, with reduced amounts of neutral lipids and a paucity of macrophages in advanced lesions. Although the latter findings may be associated with increased lesion stability, the marked alterations in cholesterol homeostasis indicate that selectively inhibiting ACAT1 in the setting of severe hyperlipidemia may have detrimental consequences.

Pyoderma gangrenosum and Chlamydia pneumoniae infection in a diabetic man: pathogenic role or coincidence?

Chlamydia Pneumoniae is not a known cause of skin infections, but unusual pathogens cause chronic infections in diabetic patients. Multiple idiopathic pyoderma gangrenosum-like (PG-like) lesions were refractory to multiple therapeutic agents in a diabetic patient who had C pneumoniae identified by serologic tests and polymerase chain reaction. Based on complete resolution by prolonged anti-chlamydial antibiotic therapy and concomitant decrease in serologic and titers determined by polymerase chain reactions, the PG-like lesions were presumed to be due to C pneumoniae.

Brown recluse spider bites

The bite of the brown recluse spider (BRS) is the most severe arthropod cause of necrotic skin lesions. The severity of cutaneous injury due to BRS bites vary from mild erythema to severe necrosis. Rarely, severe systemic reactions occur. Diagnosis may be difficult, since the victim may not feel the bite or see the spider. Treatment must be individually tailored. Proper treatment, reassurance, and rapid followup are helpful in reducing the cutaneous and psychologic discomfort associated with BRS bites.

Spontaneous alopecia areata-like hair loss in one congenic and seven inbred laboratory mouse strains

Alopecia areata (AA) research has been hampered by the lack of suitable animal models for use in experimental procedures. AA-like hair loss has been observed in several species, including dogs, cats, horses, cattle, and nonhuman primates; however, these examples are isolated cases in outbred species of large size, limiting their use in AA research. Inbred rodent strains are ideal research models. C3H/HeJ mice can develop spontaneous AA-like hair loss and have previously been advanced as a suitable experimental model. The search for additional mouse strains with AA-like hair loss has continued. Nonscarring, inflammatory, spontaneously reversible hair loss has been observed in individual mice from several inbred mouse strains. Aside from C3H/HeJ mice, an AA-like phenotype has been observed in the substrain C3H/HeJBir, with an expression frequency of 5%. Up to 10% of individuals in an A/J mouse colony have been confirmed to develop patchy AA-like hair loss. Isolated examples of AA have also been identified in C3H/HeN/J mice, C3H/OuJ mice, HRS/J+/hr heterozygous normal mice, CBA/CaHN-Btk(xid)/J mice, and BALB.2R-H2h2/Lil mice, each with a colony frequency of less than 1%. BALB.2R-H2h2/Lil mice may also have severe nail defects. AA is regarded as rare in nonhuman species; however, nonscarring inflammatory based alopecia has been identified in several mouse strains. These examples may represent different subtypes of the heterogeneous AA phenotype. Pathologic and genetic analysis of different AA affected mouse strains may contribute to understanding AA pathogenesis and elucidating susceptibility genes.

Basal cell carcinoma of the lower extremities

BACKGROUND

The most common malignancy in the USA is basal cell carcinoma. It is most prevalent on the head and neck, but can occur elsewhere. We sought to determine the frequency of basal cell carcinomas arising on the lower extremities, as well as the gender of affected patients, the histologic subtype, and the specific sites of involvement.

METHODS

We reviewed cases submitted to the Vanderbilt Dermatopathology Service between 1994 and 1997 which were diagnosed as basal cell carcinoma. A subset of 150 cases which arose on the lower extremities and a control group of 150 cases which arose at other anatomic sites were studied further.

RESULTS

A significantly greater number of basal cell carcinomas of the lower extremities arose in women, were of the superficial subtype, and were found below the knee; 59% of basal cell carcinomas in both sexes arose on the right limb.

CONCLUSION

Basal cell carcinomas of the lower extremities occur more often in women in the USA and are of the superficial subtype. This may be due to differing patterns of dress and exposure to the sun.

Tamoxifen-induced remission of psoriasis

Psoriasis vulgaris may be worsened or precipitated by numerous factors, including hormonal influences. Several lines of evidence suggest that female sex hormones such as estrogen and progesterone affect this condition. We describe a patient whose psoriasis responded favorably to administration of the antiestrogen compound tamoxifen.

Alopecia areata: an autoimmune disease?

A wide range of hypotheses such as focal infection, trophoneuroses, and endocrine dysfunction, have been previously proposed to explain the pathogenesis of alopecia areata (AA). Currently, the most widely held belief is that AA is an autoimmune disease with cellular and/or humoral immunity directed against anagen hair follicle antigen(s). However, until recently evidence in support of an autoimmune mechanism of AA has been largely circumstantial. More fundamental evidence has recently been amassed in support of AA as an autoimmune disease by using animal models. These data include: 1) identification of cross-species hair follicle specific IgG autoantibodies, 2) The ability to induce AA in an animal model with transfer of skin from affected to naive individuals, and 3) the induction of disease by transfer of lymphocytes to human skin grafted to severe combined immunodeficiency mutant mice. A review of the previous and current data related to the autoimmune basis of AA is provided to put into perspective the future studies needed to definitively determine whether AA is an autoimmune disease.

Androgenetic alopecia: in vivo models

Androgenetic alopecia is the most common form of balding in humans. There is great interest in finding a reliable animal model to study the pathogenesis and treatment of this abnormality. The sump-tailed macaque (Macaca artoides) has been the standard model and appears to be useful homologue. These primates are reasonably good predictors of compound efficacy. Due to reduced size and expense, rodent models have been sought. Testosterone inducible models require more development but offer potential. Xenografts of human skin to immunodeficient mice, notably nude or severe combined immunodeficiency, are small, relatively inexpensive, and easy to work with if a source of human tissue is available. Xenografts to double mutant mice for severe combined immunodeficiency and a number of hormone receptor null mutations offer new refinements to these xenograft models.

Recalcitrant acne vulgaris secondary to a dental abscess

This case report describes a middle-aged man with acne that was recalcitrant to numerous medications, including three courses of isotretinoin. His condition cleared after an infected tooth was removed and recurred when another tooth became carious. Acne vulgaris is associated with several immunologic responses including the production of antibodies against Propionibacterium acnes, the gram-positive bacteria found in acne lesions. We believe that the presence of our patient's dental infections provoked a follicular inflammatory response resulting in his recalcitrant acne.

Cigarette smoking-associated elastotic changes in the skin

BACKGROUND

Clinical features of the skin in persons who smoke include increased wrinkling, gauntness, and discoloration that has been termed smoker's face. The histologic changes in the sun-exposed skin of these patients have not been previously elucidated.

OBJECTIVE

The purpose of this study was to assess the amount of elastosis in the sun-exposed skin of smokers and nonsmokers.

METHODS

We evaluated the skin from the forehead and cheeks of 17 smokers and 14 nonsmokers for the presence of elastosis. With the use of a computer-generated analysis of tissue sections at 4 different levels, the amount of elastotic material was expressed as an average percent of the field staining for elastic tissue. Patients were also evaluated for the presence of other malignancies, arsenic and radiation exposure, and previous skin cancers.

RESULTS

There was a significantly greater amount of elastosis (P < .05) in the skin of patients who smoked compared with those patients who did not. No significant differences were found between the 2 groups with regard to the other parameters evaluated.

CONCLUSION

Cigarette smoking is associated with an increase in elastosis, which may contribute to the clinical features of "smoker's face."

The North American experience with photopheresis

Photopheresis or extracorporeal photochemotherapy (ECP) is a novel immunomodulatory therapy based upon pheresis of light-sensitive cells. Whole blood is removed from patients who have previously ingested the photosensitizing agent 8-methoxypsoralen (8-MOP) followed by leukapheresis and exposure of the 8-MOP containing white blood cells (WBCs) extracorporeally to an ultraviolet A (UVA) light source prior to their return to the patient. In 1988, the Food and Drug Administration (FDA) approved photopheresis for the treatment of cutaneous T-cell lymphoma (CTCL). Treatment of CTCL with photopheresis has been reported in over 300 patients worldwide. Photopheresis has also demonstrated encouraging results in the treatment of solid organ transplant rejection, graft versus host disease, scleroderma, and other autoimmune diseases although fewer patients have been studied. This review will focus on the North American experience with photopheresis.

Colchicine in dermatology

Colchicine is a medication most often used to treat symptoms of gout. This drug has also been shown to have beneficial effects on cutaneous conditions, including leukocytoclastic vasculitis, psoriasis, and Sweet's syndrome. Colchicine inhibits the function of polymorphonuclear leukocytes, and dermatoses with a strong presence of these cells may benefit the most from the administration of this medication. A review of the pharmacology, mechanism of action, and adverse reactions of colchicine is also presented.