Brown Recluse Spider Bite Manifestations and Management: Slideshow

The brown recluse spider (Loxosceles reclusa) has the potential to inflict injury. It is seen predominantly in the South Central United States. Adult spiders are soft-bodied and yellowish-tan to dark brown. They are about 1/4 to 1/2 inch long, and their leg span is about the size of a half dollar. A distinguishing characteristic is the violin-shaped marking on the dorsal cephalothorax (see Slide 2). Image courtesy of US Centers for Disease Control and Prevention.

Incidents involving the brown recluse spider usually occur in summer months. The spider prefers dark, dry, and undisturbed locations, such as woodpiles, the underside of rocks, and storage areas in garages, attics, basements, and linen closets. Bites are rare, however, even in houses that are heavily infested with spiders. For this reason, a diagnosis of a recluse bite is unlikely in areas that lack significant populations of Loxosceles spiders. Image courtesy of US Centers for Disease Control and Prevention.

It is estimated that less than 10% of envenomations result in severe skin necrosis. Wounds destined for necrosis usually show signs of progression, such as bullae formation, cyanosis, and hyperesthesia, within 6-12 hours. Central blistering surrounded by a ring of blanched skin that is itself surrounded by a large area of asymmetric erythema leads to the typical "red, white, and blue" sign of a recluse bite. In this patient, the bite area turned blue and dark red by the evening of the first day. Image courtesy of Dale Losher.

In cutaneous necrosis, a bulla develops at the center of the affected area and becomes necrotic, involving both superficial and deep tissues. Areas with increased adipose tissue, such as the thighs, buttocks, and abdomen, are more likely to undergo severe necrosis than bites occurring at other sites. Systemic loxoscelism, although unusual, may include fever, nausea, hematologic disorders, and renal failure. This image shows the wound on the third day after the bite. Image courtesy of Dale Losher.

Brown recluse spider venom is protein-based and includes sphingomyelinase D2, which acts directly on red blood cells to cause lysis. At the stage shown, these bites may be associated with significant pain related to incipient necrosis of skin and subcutaneous tissues. The resultant eschar and ulceration may take months to resolve. Patients should be advised to avoid both strenuous exercise and local heat to help limit spread of the venom. Image courtesy of Dale Losher.

Almost all recluse bites heal nicely in 2-3 months without medical treatment. When treatment is deemed appropriate, a conservative approach is best, using cold compresses, simple analgesics, elevation of an affected extremity, and cleansing of the bite site. In this severe case, the patient withstood 8 days of having an open wound to drain the spider's toxins and needed intravenous antibiotics and pain medication almost 24 hours a day. Image courtesy of Dale Losher.

Excision of a necrotic skin site may be advisable (especially for the rare large lesion) but only after an eschar has formed, adjacent tissues seem to have recovered, and normal healing is possible, which can take up to 6-8 weeks. In this patient, a 5-inch-wide area of dead tissue was excised 11 days after the bite. The extensive size of the wound necessitated skin grafting. Image courtesy of Dale Losher.

Inpatient care is not indicated for cutaneous symptoms from a recluse bite. In systemic symptoms, a hemolytic episode is seen that is usually self-limited and requires no special treatment. Systemic steroids with intravenous hydration and monitoring of renal function may be needed in some cases. At 38 days after the bite, this patient waits to see the results of the skin grafting. Image courtesy of Dale Losher.

The prognosis for recluse bites is good, and most patients show an excellent outcome. In most cases, pain subsides within 1 week, and a striking reduction in the size of the necrosis is evident. Healing may be slow, but all recluse wounds heal, usually with a minimum of scar tissue. In this severe case, the skin graft was healing well 38 days after the bite. Image courtesy of Dale Losher.

To prevent recluse bites, individuals (particularly those who live in endemic areas) should learn to recognize the brown recluse spider and become familiar with its environment. Patient awareness is the primary factor in making the correct diagnosis and forming the appropriate treatment plan for the recluse bite. This patient's large wound is fully healed approximately 10 months after the bite. Image courtesy of Dale Losher.

Dapsone has been shown to limit tissue destruction in some experimental models, but the results have been mixed and largely disappointing. A latency period of even a few hours before dapsone is started may negate any beneficial effects. Dapsone can cause hemolysis, especially in the setting of G6PD deficiency. This image shows a brown recluse bite 1 week after early use (within 72 hours) of dapsone.

After 1 month of treatment with dapsone and topical antibiotic, the lesion showed good delineation of margins and granulation tissue at its edges and base. At this stage, this eschar was debrided and healed well with topical antibiotics and daily dressing changes. Because dapsone can cause hemolysis, complete blood counts should be performed weekly for the first month and then monthly for 6 months. Treatment should be discontinued if a significant reduction in platelets, leukocytes, or hematopoiesis is noted.