A 60-year-old woman comes to the emergency department due to progressive pain, swelling, and redness of her left leg for 4 days. She has had no obvious trauma or insect bites to that area. Two months ago, the patient had a hysterectomy for endometrial hyperplasia. She also has a history of rheumatoid arthritis and gastroesophageal reflux disease. She does not use tobacco, alcohol, or illicit drugs. Temperature is 39.4 C (102.9 F), blood pressure is 130/80 mm Hg, pulse is 106/min, and respirations are 18/min. The patient appears well. Her left anterior leg is swollen, erythematous, tender, and warm to the touch over a 10x5 cm region, as shown in the exhibit. The erythema is present throughout the affected area and has a flat border. There is no overlying crepitus or bullae. The left thigh and right leg are normal in appearance. The remainder of the examination is normal. Laboratory results are as follows: Which of the following is the most likely diagnosis?

Question

A 60-year-old woman comes to the emergency department due to progressive pain, swelling, and redness of her left leg for 4 days.  She has had no obvious trauma or insect bites to that area.  Two months ago, the patient had a hysterectomy for endometrial hyperplasia.  She also has a history of rheumatoid arthritis and gastroesophageal reflux disease.  She does not use tobacco, alcohol, or illicit drugs.  Temperature is 39.4 C (102.9 F), blood pressure is 130/80 mm Hg, pulse is 106/min, and respirations are 18/min.  The patient appears well.  Her left anterior leg is swollen, erythematous, tender, and warm to the touch over a 10x5 cm region, as shown in the exhibit.  The erythema is present throughout the affected area and has a flat border.  There is no overlying crepitus or bullae.  The left thigh and right leg are normal in appearance.  The remainder of the examination is normal.  Laboratory results are as follows:  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec25c8_d38c_58f5_bc81_1bd4127d3d49_MD0003_00 Cellulitis is a skin infection of the deep dermis and subcutaneous fat usually caused by beta hemolytic Streptococcus (nonpurulent) or Staphylococcus aureus (purulent). Infections take root in areas of skin disruption (eg, insect bite, toe-web impetigo, stasis edema). Patients typically develop a slowly spreading rash that is warm, tender, and erythematous with flat, indistinct borders. Fever and regional lymphangitis/lymphadenitis may be present. Laboratory studies usually show leukocytosis with a predominance of neutrophils, a characteristic of most acute bacterial infections. Diagnosis is based largely on clinical findings, but blood cultures may be useful in patients with systemic toxicity, extensive rash, or certain comorbidities (eg, immunocompromised). (Choice B) Deep venous thrombosis may cause calf swelling, erythema, and warmth. An anterior rash, high fever, and leukocytosis are not typical. (Choice C) Erysipelas is similar in etiology (generally streptococci) and clinical presentation to cellulitis. However, erysipelas is limited to the epidermis and superficial dermis, which gives erysipelas its characteristic raised, sharp borders and intense erythema. Erysipelas (Choice D) Erythema nodosum is a delayed hypersensitivity reaction usually characterized by subcutaneous, bilateral, anterior leg nodules (inflammation of subcutaneous tissues). It is associated with infectious (eg, streptococcal pharyngitis), autoimmune (eg, sarcoidosis), or inflammatory processes (eg, inflammatory bowel disease). Polyarthralgia, fever, and malaise are common. This patient has a flat, unilateral skin rash. Erythema nodosum (Choice E) Necrotizing fasciitis is a destructive infection of the fascia and subcutaneous fat marked by severe pain, systemic toxicity, bullae, crepitus, and skin necrosis. (Choice F) A ruptured Baker cyst may cause pain, warmth, and erythema in the popliteal fossa and posterior calf. High fever, leukocytosis, and a localized anterior rash would be uncommon. (Choice G) Toxic shock syndrome is a toxin-mediated illness marked by the rapid onset of fever, hypotension, and diffuse skin rash that includes the palms and soles. This patient has a localized rash and no hypotension. Educational objective: Cellulitis is a skin infection of the deep dermis and subcutaneous fat that is usually caused by beta hemolytic Streptococcus (nonpurulent) or Staphylococcus aureus (purulent). Patients typically develop a slowly spreading rash that is warm, erythematous, and painful with flat, indistinct borders. References: Practice guidelines for the diagnosis and management of skin and soft-tissue infections. (http://www.ncbi.nlm.nih.gov/pubmed/16231249) Skin and soft tissue infections in immunocompetent patients. (http://www.ncbi.nlm.nih.gov/pubmed/20353147)

A 60-Year-Old Woman Comes to the Emergency Department Due to Progressive