A 38-year-old woman comes to the emergency department complaining of severe pain and swelling in her left leg. She fell 2 days ago while playing recreation-league soccer and suffered a mildly painful abrasion to her posterior left thigh. The pain has worsened steadily since and is now unbearable. Initially only her left proximal thigh was painful and red, but now the pain has spread to her buttock and proximal calf. The patient also complains of fatigue and chills. Her temperature is 39.4 C (102.7 F), blood pressure is 82/60 mm Hg, pulse is 104/min, and respirations are 18/min. Physical examination shows a swollen left thigh with moderate erythema over the left proximal thigh and buttock. The buttock and distal thigh are markedly tender to palpation, and the patient has no sensation to light touch over the proximal thigh. Blood pressure improves with intravenous fluids. CT scan of the affected area is shown in the exhibit. Which of the following is the most likely diagnosis in this patient?

Question

A 38-year-old woman comes to the emergency department complaining of severe pain and swelling in her left leg.  She fell 2 days ago while playing recreation-league soccer and suffered a mildly painful abrasion to her posterior left thigh.  The pain has worsened steadily since and is now unbearable.  Initially only her left proximal thigh was painful and red, but now the pain has spread to her buttock and proximal calf.  The patient also complains of fatigue and chills.  Her temperature is 39.4 C (102.7 F), blood pressure is 82/60 mm Hg, pulse is 104/min, and respirations are 18/min.  Physical examination shows a swollen left thigh with moderate erythema over the left proximal thigh and buttock.  The buttock and distal thigh are markedly tender to palpation, and the patient has no sensation to light touch over the proximal thigh.  Blood pressure improves with intravenous fluids.  CT scan of the affected area is shown in the exhibit.  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

11ec25c8_d848_0cf7_bc81_5592b41fdc58_MD0003_00 This patient has fever, hypotension, erythema, and swelling. Notably, she has pain out of proportion to the physical examination findings. In addition, her CT scan is suggestive of air in the deep tissue. This constellation of findings is concerning for necrotizing fasciitis. Necrotizing fasciitis is a rapidly spreading infection involving the subcutaneous fascia, generally following trauma. It can also result from significant peripheral vascular disease (ie, diabetes). Group A streptococci is the most frequently recovered pathogen, although necrotizing fasciitis is usually polymicrobial. Gas production by microbes leads to air in the soft tissues, which results in crepitus on examination in about 50% of cases. CT scan Patients with necrotizing fasciitis have pain and swelling of the affected site. The pain is frequently more severe than expected based on the degree of swelling and erythema and usually precedes systemic signs such as fever or hypotension. Untreated necrotizing fasciitis progresses to rapid discoloration of the affected site, purulent discharge, bullae, and necrosis. Imaging can reveal the extent of the infection and identify air in the tissue bed. However, if necrotizing fasciitis is strongly suspected, therapy should not be delayed to pursue additional imaging. Broad-spectrum antibiotic therapy and resection of necrotic tissue are necessary for treatment. Because of its rapid progression, necrotizing fasciitis causes significant morbidity and mortality even with aggressive treatment. (Choice A) Skin and soft-tissue infections that are successfully limited by the immune system and tissue barriers present as abscesses. Abscesses are localized to a tender, fluctuant area and do not spread aggressively as does necrotizing fasciitis. Systemic signs such as hypotension and high fever are unusual. (Choice B) Cellulitis is an acute skin infection that presents with warmth, erythema, edema, and tenderness. Evidence of underlying tissue necrosis, including severe pain or crepitus or systemic signs such as hypotension, should raise concern for a more aggressive process such as necrotizing fasciitis or other deep-tissue infection. (Choice C) Deep-muscle hematomas can occur with moderate to severe trauma. Deep hematomas that arise with minor trauma are not commonly seen except in patients with bleeding disorders. Hematomas may be tender to palpation, but signs of infection such as erythema, fever, and hypotension are not consistent with hematoma. (Choice E) Pyomyositis (muscle abscess) may have a very similar clinical presentation compared to necrotizing fasciitis, with fever, erythema, swelling, and pain. However, pyomyositis is generally limited to one muscle group and does not spread rapidly. This patient also has air in the tissue planes on CT scan, which is consistent with necrotizing fasciitis. (Choice F) Thrombophlebitis is characterized by erythema, tenderness, and swelling of the distal extremity along with a palpable, "cord-like" vein. Findings of tissue necrosis or shock are inconsistent with thrombophlebitis. (Choice G) Toxic shock syndrome is characterized by diffuse erythematous skin rash and hypotension followed by multi-organ dysfunction. The rash of toxic shock syndrome is neither localized nor painful. Educational objective: Necrotizing fasciitis presents with erythema and swelling, severe pain out of proportion to the physical examination, and signs of tissue necrosis such as crepitus, purulent drainage, or radiographic evidence of gas in the deep tissues. When skin or soft-tissue infection is suspected, rapid progression of physical examination findings or severe systemic signs such as hypotension should raise suspicion for necrotizing fasciitis. References: Necrotizing fasciitis: contribution and limitations of diagnostic imaging. (http://www.ncbi.nlm.nih.gov/pubmed/23043899)

A 38-Year-Old Woman Comes to the Emergency Department Complaining of Severe