A 36-year-old woman comes to the urgent care clinic due to worsening right lower extremity pain and swelling for the past several days. The patient has a history of injection drug use. She also exchanges sex for drugs and is inconsistent with condom use. Temperature is 37.1 C (98.8 F), blood pressure is 126/76 mm Hg, pulse is 86/min, and respirations are 13/min. Oxygen saturation is 98% on room air. On physical examination, edema, erythema, and warmth of the right leg are noted with increased calf and thigh diameters. There are injection marks in the right groin. Which of the following is the most likely diagnosis?

Question

A 36-year-old woman comes to the urgent care clinic due to worsening right lower extremity pain and swelling for the past several days.  The patient has a history of injection drug use.  She also exchanges sex for drugs and is inconsistent with condom use.  Temperature is 37.1 C (98.8 F), blood pressure is 126/76 mm Hg, pulse is 86/min, and respirations are 13/min.  Oxygen saturation is 98% on room air.  On physical examination, edema, erythema, and warmth of the right leg are noted with increased calf and thigh diameters.  There are injection marks in the right groin.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec25c8_d846_3835_bc81_71fb3a133557_MD0003_00 This patient with a history of injection drug use has right leg edema, erythema, and warmth. Although these symptoms often occur in a localized manner in injection drug users due to skin and soft tissue infection, the presence of symptoms in the entire leg, increased thigh and calf diameters, and injection marks in the right groin raises strong suspicion for acute iliofemoral deep venous thrombosis (DVT). Common risk factors for first DVT include prolonged immobility or hospitalization, recent major surgery, obesity, malignancy, oral contraceptive/hormone replacement use, and pregnancy. However, patients who inject drugs into the femoral vein also are at high risk for DVT due to iliofemoral venous wall trauma, chemical irritation, and/or infection. Manifestations of lower extremity DVT generally include unilateral leg swelling, pain, and warmth; physical examination often reveals dilated superficial veins and increased diameter of the calf or thigh when compared to the unaffected leg. Initial evaluation typically includes D-dimer (in those with low or moderate pretest probability) and/or lower extremity Doppler ultrasound examination (in those with high pretest probability). (Choice A) Acute lymphangitis is a common complication of injection drug use due to inoculation of skin flora into subcutaneous tissue. However, this condition is generally marked by tender red streaks up the lymphatic channels with painful, swollen, erythematous regional lymphadenitis. The presence of diffuse right leg symptoms and increased calf or thigh diameter enlargement makes DVT far more likely. (Choice C) Chronic lymphatic filariasis often results in limb lymphedema due to long-standing lymphatic inflammation. However, most cases occur in sub-Saharan Africa, Southeast Asia, the Caribbean, and the Indian subcontinent. In addition, this patient with injection marks in the right groin is far more likely to have acute DVT due to iliofemoral vein injury. (Choice D) Lymphogranuloma venereum is a tropical and subtropical disease caused by serovars of Chlamydia trachomatis; it is marked by genital ulcers and inguinal lymphadenitis. (Choice E) Necrotizing myositis is a rare condition generally marked by severe systemic toxicity (eg, high fever, hypotension, toxic appearance) and rapidly progressive skin changes (eg, discoloration, gangrene). This patient's normal vital signs and slow-onset symptoms make this highly unlikely. Educational objective: Patients who inject drugs into the femoral vein can develop iliofemoral deep venous thrombosis. This disorder is typically marked by unilateral leg edema, warmth, and erythema with evidence of dilated superficial veins and increased calf/thigh diameter on examination.

A 36-Year-Old Woman Comes to the Urgent Care Clinic Due