spider venom injected into 41 rabbits highlighted this variability when comparing results to nine other studies reporting histological changes in both rabbit models and human patients after brown recluse venom exposure. 6 A biopsy specimen was also collected for tissue culture and returned negative for atypical mycobacteria, fungus, aerobic and anaerobic bacteria( Figure 1).
After we told the patient a spider bite was part of the differential, he reported a recent history of walking in overgrown grass near a vacant home. It’ s been suggested that a brown recluse bite should be considered when patients present with a significant area of dermal necrosis. 1, 5, 7 The patient was seen by plastic surgery and the necrotic area underwent debridement( Figure 2). Local wound care was used for one week before the area was viewed again by plastic surgery, who noted prominent formation of granulomas in the debridement area. A surgical closure of the area was then performed. A drain was placed and removed post-operatively after one week. The surgical site went on to heal without significant complications. Surgical management is common in brown recluse bites with areas of significant necrosis, and skin grafts can be required in severe wounds such as the one described in this report. 7 Skin on the patient’ s buttock was marked for use in a possible graft but a primary closure was successfully performed. Treatment of bites that do not require surgical intervention tends to be conservative, with limited evidence suggesting a benefit from medications such as dapsone or colchicine. 2, 8
While this case describes a severe manifestation of a brown recluse bite, the mnemonic“ NOT RECLUSE” may serve as a helpful tool in determining whether lesions adhere to the typical presentation associated with L. reclusa to prevent misdiagnosis. 9 It should be noted that presentations of dermonecrosis can often be misattributed to the brown recluse, and differential diagnoses should be considered. 2, 9 Lesions are often singular( N = numerous), lack a red center( R = red) and are rarely elevated above 1 cm( E = elevation). Furthermore, typical lesions are smaller than 10 cm( L = large), do not ulcerate until one-two weeks after envenomation( U = ulcerates) and rarely take longer than three months to heal( C = chronic). Bites are also associated with events in which the environment of secluded spiders is disturbed( O = occurrence). Higher suspicion should also arise when patients reside in areas native to the spider and the bite occurs between April and October, during the spiders’ North American activity season( T = timing). 9
This report features a patient from Kentucky, a state in which a significant number of spider envenomation cases can be attributed to the brown recluse. 2 The characteristics of this lesion, as well as the patient’ s location and history, allowed for similarly presenting conditions to be ruled out in favor of a severe presentation of L. reclusa envenomation.
References
1
Elston DM. What’ s eating you? Loxosceles reclusa( brown recluse spider). Cutis. 2002; 69:91-2, 4-5.
2
Swanson DL, Vetter RS. Bites of brown recluse spiders and suspected necrotic arachnidism. N Engl J Med. 2005; 352:700-7.
3
Tarullo DB, Jacobsen RC, Algren DA. Two successive necrotic lesions secondary to presumed loxosceles envenomation. Wilderness Environ Med. 2013; 24:132-5.
4
Hart SA, Gailani D, Bibb LA, Zwerner JP, Booth GS, Jacobs JW. Coagulation abnormalities following brown recluse spider( Loxosceles reclusa) envenomation: A description of 2 cases and review of the literature. Am J Clin Pathol. 2025.
5
Rees RS, Altenbern DP, Lynch JB, King LE, Jr. Brown recluse spider bites. A comparison of early surgical excision versus dapsone and delayed surgical excision. Ann Surg. 1985; 202:659-63.
6
Elston DM, Eggers JS, Schmidt WE, Storrow AB, Doe RH, McGlasson D, et al. Histological findings after brown recluse spider envenomation. Am J Dermatopathol. 2000; 22:242-6.
7
Gomez HF, Greenfield DM, Miller MJ, Warren JS. Direct correlation between diffusion of Loxosceles reclusa venom and extent of dermal inflammation. Acad Emerg Med. 2001; 8:309-14.
8
Elston DM, Miller SD, Young RJ, 3rd, Eggers J, McGlasson D, Schmidt WH, et al. Comparison of colchicine, dapsone, triamcinolone, and diphenhydramine therapy for the treatment of brown recluse spider envenomation: a double-blind, controlled study in a rabbit model. Arch Dermatol. 2005; 141:595-7.
9
Stoecker WV, Vetter RS, Dyer JA. NOT RECLUSE-A Mnemonic Device to Avoid False Diagnoses of Brown Recluse Spider Bites. JAMA Dermatol. 2017; 153:377-8.
Lilah Kahloon is a third-year medical student at the University of Louisville School of Medicine.
Dr. Schrodt is a board-certified adult and pediatric dermatologist practicing at Dermatology Associates, PSC.
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