Case Presentation: A 79 year old man with a history of prostate cancer s/p transurethral resection of the prostate complicated by urethral stricture, urinary retention, and incontinence, congenital unilateral kidney, recurrent deep vein thromboses (DVT) not on anticoagulation, and bilateral knee replacements presented with swelling and redness of his right leg following a 6-hour drive 2 weeks prior to presentation. He was afebrile and his other vital signs were normal. His medial right thigh was erythematous and indurated with no rashes or breaks in skin. Laboratory findings were remarkable for a leukocytosis of 12. A duplex ultrasound of the right lower extremity revealed a right femoral DVT. He was treated with enoxaparin. He was later started on IV vancomycin and ceftriaxone as his left lower extremity started becoming erythematous as well, and he became persistently febrile with a worsening leukocytosis to 22.Given his lack of improvement on IV antibiotics, a CT scan of his lower extremities was ordered revealing large multiloculated collections in his bilateral quadriceps, thought to be abscesses versus hematomas. He was HIV and hepatitis negative. He had no other major comorbidities such as diabetes or kidney disease. He reported no constitutional symptoms suggestive of a recurrence of malignancy, no recent travel, and no recent falls or trauma.Due to a lack in clinical improvement on IV antibiotics for 10 days, he first underwent ultrasound guided drainage of the collections which revealed frank pus. He then underwent surgical debridement of the bilateral thigh abscesses. Cultures grew E. faecalis. His antibiotics were changed to IV ampicillin/sulbactam, which he received for 2 weeks post-op. He clinically improved post-op and was discharged on oral amoxicillin/clavulanate for 5 weeks. At outpatient follow up 1 month later, he was able to ambulate without pain, and a repeat CT scan showed complete resolution of the left thigh abscess with a decrease in size of the right thigh collection.
Discussion: Pyomyositis is a primary skeletal muscle infection with abscess formation that may be caused by hematogenous spread in the setting of pre-existing muscle damage. It is usually an infection of the tropics with affected patients who are otherwise healthy. In temperate climates such as the United States, patients tend to be immunocompromised or have other major comorbidities such as diabetes. The most common culprit organism is S. aureus, whereas our patient was infected with E. faecalis. Interestingly, a urine culture collected at the beginning of his admission also resulted positive for E. faecalis. As our patient first began to feel ill weeks before presentation, we believe he had a preceding urinary tract infection (UTI) with transient bacteremia and subsequent hematogenous seeding of the bilateral quadriceps. Although he did not have active malignancy or other major comorbidities which could put him at risk of developing pyomyositis, he did have a significant genitourinary history requiring frequent self-catheterization and penile clamping. This likely made him prone to complicated UTI, bacteremia, and later pyomyositis with the same culprit organism.
Conclusions: Lower extremity erythema, warmth, pain, and edema is often mistaken for cellulitis and thromboembolic disease. In patients who are prone to complicated UTI, such as those who frequently catheterize, who present with lower extremity pain and swelling, physicians should consider pyomyositis as part of their workup.