A 62-year-old woman comes to the emergency department due to fever and right foot pain. She has had increasing redness, warmth, and swelling at the dorsum of the right foot for the last 2 days and woke with pain and subjective fever today. The patient also has had itching in the skin under and between the toes for the last 6 months. Medical history is notable for obesity and type 2 diabetes mellitus. She does not use tobacco or alcohol. The patient works as a restaurant dishwasher and spends most of the day wearing waterproof rubber shoes. Temperature is 38.2 C (100.8 F), blood pressure is 166/98 mm Hg, and pulse is 102/min. Examination shows erythema and edema at the dorsum of the foot with palpable warmth and an indistinct border. There is extensive scaling and flaking of the skin between the toes. Examination findings are shown in the image below: Palpation of the right inguinal region shows 3 or 4 slightly tender lymph nodes. Which of the following is the most likely cause of this patient's acute symptoms?

Question

A 62-year-old woman comes to the emergency department due to fever and right foot pain.  She has had increasing redness, warmth, and swelling at the dorsum of the right foot for the last 2 days and woke with pain and subjective fever today.  The patient also has had itching in the skin under and between the toes for the last 6 months.  Medical history is notable for obesity and type 2 diabetes mellitus.  She does not use tobacco or alcohol.  The patient works as a restaurant dishwasher and spends most of the day wearing waterproof rubber shoes.  Temperature is 38.2 C (100.8 F), blood pressure is 166/98 mm Hg, and pulse is 102/min.  Examination shows erythema and edema at the dorsum of the foot with palpable warmth and an indistinct border.  There is extensive scaling and flaking of the skin between the toes.  Examination findings are shown in the image below:  Palpation of the right inguinal region shows 3 or 4 slightly tender lymph nodes.  Which of the following is the most likely cause of this patient's acute symptoms?

Quizplus · Accepted Answer

11ec25c8_d288_cc50_bc81_5db38b30296d_MD0003_00 This patient with erythema, warmth, and swelling of the foot associated with fever and lymphadenopathy has cellulitis, a bacterial infection that involves the deep dermis or subcutaneous fat. Cellulitis typically occurs when gram-positive skin flora (eg, beta-hemolytic Streptococcus, Staphylococcus aureus) gain access to the subcutaneous space via breaks in the skin (eg, trauma, insect bites, preexisting skin infection). This patient with chronic interdigital pruritus and skin flaking likely developed cellulitis as a complication of tinea pedis (TP), a dermatophyte infection most commonly caused by Trichophyton rubrum. TP is one of the most common risk factors for lower extremity cellulitis. Dermatophytes are generally noninvasive but cause fissuring, erosions, and ulceration that allow bacterial entry into the tissue, particularly when the feet are chronically wet or occluded (eg, by nonbreathable footwear, as in this patient who wears rubber shoes). Patients with immunosuppression (eg, uncontrolled diabetes) are at particularly high risk of developing both severe TP and secondary cellulitis. (Choice A) Acute allergic contact dermatitis presents with erythematous plaques, often associated with vesicle formation, oozing, or crusting. Itching is typically intense. However, diffuse redness, pain, and fever are more typical of cellulitis, and this patient's rubber footwear would likely cause bilateral symptoms. (Choice B) Deep venous thrombosis can present with lower extremity pain, swelling, and occasionally erythema and fever. However, the swelling and erythema typically involve the posterior leg or calf, rather than being isolated to the dorsum of the foot (as in this patient), and regional lymphadenopathy is more consistent with cellulitis. (Choice C) Immune complications of TP include local or remote vesicular or bullous skin reactions. bullous (Choice E) Lymphatic invasion and obstruction is common in some fungal infections (eg, sporotrichosis) but uncommon in TP. The regional adenopathy noted in this patient is a common finding in cellulitis. Educational objective: Cellulitis occurs when gram-positive skin flora gain access to the subcutaneous space via breaks in the skin. Tinea pedis, one of the most common risk factors for lower extremity cellulitis, causes fissuring, erosions, and ulceration that allow bacterial entry into the tissue. References: Risk factors for nonpurulent leg cellulitis: a systematic review and meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/27864837)

A 62-Year-Old Woman Comes to the Emergency Department Due to Fever