Sonographic Appearance of Angioedema in Local Allergic Reactions to Insect Bites and Stings

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1 CSE SERIES Sonographic ppearance of ngioedema in Local llergic Reactions to Insect ites and Stings Ee Tein Tay, MD, James W. Tsung, MD, MPH Soft tissue infections and angioedema from insect bites and stings may be difficult to differentiate by inspection. We present sonographic findings of 4 cases of soft tissue swelling from insect bites and stings suggestive of angioedema. Sonographic features of soft tissue angioedema consist of thickened subcutaneous tissue layers with multiple linear, horizontal, striated, and hypoechoic lines following the tissue planes between soft tissue layers. In addition to the history and physical examination, sonographic findings may assist in differentiating between local allergic reactions and cellulitis in patients with insect bites and stings. Further study is warranted for clinical application. Key Words allergic reaction; angioedema; insect bites; insect stings; point-of-care ultrasound; sonography Received November 18, 2013, from the Departments of Emergency Medicine and Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York US. Revision requested December 5, Revised manuscript accepted for publication January 10, ddress correspondence to Ee Tein Tay, MD, Department of Emergency Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Pl, 1149, New York, NY US. eetaymd@gmail.com bbreviations ED, emergency department doi: /ultra S oft tissue swelling related to insect bites and stings is a common presentation in the emergency department (ED). Differentiating between cellulitis and angioedema caused by a local allergic reaction on visual inspection may be difficult, especially when evidence of an insect bite or sting is not apparent. 1 This diagnostic uncertainty may lead to the overuse of antibiotics when cellulitis is not present. lthough previous studies have used sonography to describe the characteristics of cellulitis and skin abscesses, none have described the sonographic findings of angioedema caused by local allergic reactions. 2 9 Here, we describe 4 cases of patients who presented with soft tissue swelling from insect bites or stings and their point-of-care sonographic appearances of angioedema caused by local allergic reactions. Case Descriptions Case 1 5-year-old girl presented with a swollen right hand for 1 day. small pruritic pimple was noted the day before and was suspected to be an insect bite. Her hand became progressively swollen throughout the day of presentation. She was afebrile, and no medication was given at home. Physical examination showed a nontender, erythematous, swollen right hand with fluctuance and a central punctum (Figure 1). No induration or crepitus was noted by the merican Institute of Ultrasound in Medicine J Ultrasound Med 2014; 33:

2 Tay and Tsung ngioedema in Local llergic Reactions to Insect ites and Stings Case 2 n 8-year-old boy presented with a swollen right foot for 1 day. He had tried to step on wasps with his bare foot the day before and thought he may have been stung in the process. He had mild pruritus and a subjective fever. No medications were given at home. Physical examination revealed an afebrile patient with a swollen, erythematous dorsal right foot with mild induration (Figure 2). No fluctuance, crepitus, calor, or tenderness was appreciated on palpation. Several puncta were noted on the dorsal foot but none on the plantar surface. Figure 2. Case 2., Right foot swelling and erythema compared to the normal left foot., Transverse sonographic view of right foot swelling. C, Transverse sonographic view of the normal left foot. Case 3 4-year-old boy presented with a swollen right hand from an insect bite earlier in the day. He had pruritus without pain and was afebrile. The hand became progressively swollen throughout the day. No medications were given at home. Physical examination showed a swollen, fluctuant, nontender right hand without calor, induration, or crepitus (Figure 3). punctum was noted on the dorsal hand. Figure 1. Case 1., Right hand swelling with a central punctum compared to the normal left hand., Transverse sonographic view of right hand swelling. C 1706 J Ultrasound Med 2014; 33:

3 Tay and Tsung ngioedema in Local llergic Reactions to Insect ites and Stings Case 4 3-year-old boy presented with a swollen left upper eyelid and left side of the forehead for 1 day after sustaining an insect bite to the forehead. Topical hydrocortisone was applied for pruritus without improvement. Physical examination revealed an afebrile child with multiple puncta on the left forehead and a swollen left upper eyelid (Figure 4). There was mild erythema around the puncta and over the left upper eyelid. No induration, fluctuance, crepitus, or tenderness on palpation was noted on examination. Figure 3., Right hand swelling compared to the normal left hand., Transverse sonographic view of right hand swelling. Scan Technique Sonography was performed with an M-Turbo ultrasound machine and a high-resolution 13 6-MHz linear array transducer (SonoSite, Inc, othell, W). Sonography of the extremities was performed by a water bath technique. Conventional linear array scans without spatial compounding or Doppler imaging were performed. Transverse and longitudinal views were obtained over the area of maximum swelling. Sonography in all 4 cases showed thickened subcutaneous tissue layers with multiple linear, striated, horizontal, and hypoechoic lines following the tissue planes between soft tissue layers (Figures 1, 2, 3, and 4). The hypoechoic lines were located within the subcutaneous tissue, sparing muscle tissue. The thickness and location of these lines varied within the soft tissue plane: either superficial, deep within the tissue, or both. The extremities appeared to have more thickened soft tissue and linear lines than areas with limited room for tissue expansion, such as Figure 4. Case 4., Left upper eyelid swelling with lateral forehead erythema compared to the normal right eyelid., Transverse sonographic view of left upper eyelid swelling. C, Transverse sonographic view of the normal right eyelid. C J Ultrasound Med 2014; 33:

4 Tay and Tsung ngioedema in Local llergic Reactions to Insect ites and Stings the eyelid. There were no distinct margins or increases or decreases in the echogenicity of the affected tissue. When compared, sonography of the contralateral sides did not show thickened skin or linear, horizontal, and striated lines (Figures 2C and 4C). These findings were seen in both transverse and longitudinal views. Discussion The use of point-of-care sonography for soft tissue evaluations in the ED has predominantly been used for the detection of infections in cutaneous cellulitis and abscesses, peritonsillar abscesses, and necrotizing fasciitis. 2 9 Previous studies have used sonography to measure subcutaneous skin thicknesses from limb swelling in immunization reactions and evaluation of soft tissue thicknesses in response to patch test reactions on -mode sonography, 10,11 but none have described the appearances of soft tissue angioedema caused by local allergic reactions on -mode scans. ased on our cases, soft tissue angioedema in local allergic reactions from insect bites and stings appears to be thickened on sonography with multiple, linear, horizontal, and striated hypoechoic bands within the tissue (Figure 5). Sonographic features of cellulitis on sonography include skin thickening, subcutaneous edema, and the appearance of haziness and fluid surrounding fat globules, termed cobblestoning 2 9 (Figure 5). s cellulitis may be difficult to discern from a local allergic reaction on physical examination because of similar findings on inspection, 1 the clinical history in conjunction with sonographic features may assist in diagnosis and management. Patients with cellulitis would be expected to have skin swelling, tenderness on palpation overlying the affected area, calor, and expansion of erythema from the initial site, and fever may often develop. In patients with angioedema, physical findings may include skin swelling with the presence of puncta, skin erythema, excoriation from pruritus, and often tenderness in areas with less room for tissue expansion. Findings from local allergic reactions are more immediate, usually peaking at 24 to 48 hours, 12 whereas cellulitis tends to develop later in the course. Cellulitis from insect bites and stings may also occur. 1,13 s we compiled this case series, we encountered a patient with 3 days of left calf redness and tenderness surrounding a punctum from a spider bite (Figure 6). Sonography of his left calf showed skin thickening, haziness, and a swirling, cobblestone-like soft tissue pattern suggesting early cellulitis when compared to his normal left calf (Figure 6, and C). The subcutaneous horizontal hypoechoic bands suggesting angioedema were absent on sonography in this patient. This case supports the idea that it may be possible to develop cellulitis from insect bites and stings, 1,13 and with a history and physical examination, the use of sonography may assist in distinguishing between cellulitis and angioedema. In all 4 cases, antibiotics were not prescribed, and patients were discharged with antihistamines for local allergic reactions. Patients were instructed to return to the ED if they developed increased redness, fever, calor, or pain at the bite or sting sites. lthough none of the patients returned to our ED for further evaluation of skin findings, this fact does not exclude the possibility that the patients may have been followed at other institutions for further medical care. Previous cases have described the development of cellulitis from insect bites and stings and their association with methicillin-resistant Staphylococcus aureus and methicillin-sensitive S aureus infections. 1,14,15 Cellulitis has also been mistaken as spider bites and has been subsequently cultured as methicillin-resistant S aureus infections. 16 ntibiotic resistance has been increasing worldwide due to factors such as overprescription of antibiotics and development of different resistant strains of bacteria. 17,18 Figure 5., Horizontal linear bands of edema in angioedema on sonography., Example of cobblestoning in cellulitis on sonography J Ultrasound Med 2014; 33:

5 Tay and Tsung ngioedema in Local llergic Reactions to Insect ites and Stings With the emergence of antibiotic resistance, it is possible that sonography may assist in promoting antibiotic stewardship by evaluating whether infections are present and whether antibiotics are warranted. In summary, multiple horizontal bands of edema within the thickened soft tissue on sonography appear to suggest angioedema in patients with local allergic reactions to insect bites and stings. lthough further studies are warranted for Figure 6., Left calf of a patient with a recent spider bite. and C, Transverse sonographic view of the affected left calf () suggesting cellulitis compared to a transverse view of the normal right calf (C). C clinical application of these findings, we hope that sonography may be used as an adjunctive tool in conjunction with the history and physical examination to assist in differentiating between cellulitis and allergic reactions and ultimately promoting judicious prescription of antibiotics and antibiotic stewardship. References 1. Derlet RW, Richards JR. Cellulitis from insect bites: a case series. Cal J Emerg Med 2003; 4: Sivitz D, Lam SHF, Ramirez-Schrempp D, Valente JH, Nagdev D. Effect of bedside ultrasound on management of pediatric soft-tissue infection. J Emerg Med 2010; 39: Ramirez-Schrempp D, Dorfman DH, aker WE, Liteplo S. Ultrasound soft tissue applications in the pediatric emergency department: to drain or not to drain? Pediatr Emerg Care 2009; 25: Tayal VS, Hasan N, Norton HJ, Tomaszewski C. The effect of soft-tissue ultrasound on the management of cellutitis in the emergency department. cad Emerg Med 2006; 13: Squire T, Fox JC, nderson C. SCESS: applied bedside sonography for convenient evaluation of superficial soft tissue infections. cad Emerg Med 2005; 12: Chau CLF, Griffith JF. Musculoskeletal infections: ultrasound appearances. Clin Radiol 2005; 60: Huang MN, Chang YC, Wu CH, Hsieh SC, Yu CL. The prognostic values of soft tissue sonography for adult cellulitis without opus or abscess formation. Intern Med J 2009; 39: Robben SGF. Ultrasonography of musculoskeletal infections in children. Eur Radiol 2004; 14(suppl 4):L65 L Loyer EM, Durow R, David CL, Coan JD, Eftekhari F. Imaging of superficial soft-tissue infections: sonographic findings in cases of cellulitis and abscess. JR m J Roentgenol 1996; 166: Marshall HS, Gold MS, Gent R, et al. Ultrasound examination of extensive limb swelling reactions after diphtheria-tetanus-acellular pertussis or reduced-antigen content diphtheria-tetanus-acellular pertussis immunization in preschool-aged children. Pediatrics 2006; 118: Serup J, Staberg. Ultrasound for assessment of allergic and irritant patch test reactions. Contact Dermatitis 1987; 17: Severino M, onadonna P, Passalacqua G. Large local reactions from stinging insects: from epidemiology to management. Curr Opin llergy Clin Immunol 2009; 9: Slevogt H, Schiller R, Wesselmann H, Suttorp N. scending cellulitis after an insect bite. Lancet 2001; 357: Golding GR, Levett PN, McDonald RR, et al. comparison of risk factors associated with community-associated methicillin-resistant and -susceptible Staphylococcus aureus infections in remote communities. Epidemiol Infect 2010; 138: Cohen PR. Community-acquired methicillin-resistant Staphylococcus aureus skin infections: implications for patients and practitioners. m J Clin Dermatol 2007; 8: J Ultrasound Med 2014; 33:

6 Tay and Tsung ngioedema in Local llergic Reactions to Insect ites and Stings 16. Segarra-Newnham M. Skin infections with methicillin-resistant Staphylococcus aureus presenting as insect or spider bites. m J Health Syst Pharm 2006; 63: Tenover FC, Hughes JM. The challenges of emerging infectious diseases: development and spread of multiply-resistant bacterial pathogens. JM 1996; 275: Huges JM, Tenover FC. pproaches to limiting emergency of antimicrobial resistance in bacteria in human populations. Clin Infect Dis 1997; 24(suppl 1):S131 S J Ultrasound Med 2014; 33: