ACNE IN THE PROSTATE: A CASE OF AN EMPHYSEMATOUS PROSTATIC ABSCESS

Case

Our patient is a 78-year-old man who presents to the emergency room with fever and perineal pain. His medical history includes prostate cancer, status post external beam radiation therapy 15 years ago as well as a urethral stricture, status post-dilation five years ago. He has no recent history of urethral instrumentation or procedures. He denies tobacco, alcohol, and intravenous drug use. Current medications are amlodipine, atorvastatin, tamsulosin, finasteride, and hydrochlorothiazide.

On physical exam, his temperature is 99.5°F and other vitals are within normal limits. He is an elderly male who appears uncomfortable and disoriented. He is alert and oriented to his name with no other focal deficits but could not name the days of the week backward. The abdomen is scaphoid, non-tender, and non-distended, with normoactive bowel sounds. There is a prior suprapubic catheter scar. A prostate exam shows an enlarged prostate with prostatic fluctuance. He has left inguinal pain. There is no urethral discharge or ulcers.

Pertinent labs include an elevated white count (15,300) with 84% PMNs and a basic metabolic profile is within normal limits. Urinalysis shows 15-25 WBC/hpf, 15-25 RBC/hpf, 2+ bacteria, + leukocyte esterase, and + nitrite. CT scan of the abdomen and pelvis with contrast shows an air collection that communicates with the undersurface of the bladder and a focus of air in the prostatic urethra with no definitive abscess. Blood cultures x two grow Propionibacterium acnes (Cutibacterium acnes) in two of four bottles (sensitive to penicillin). The patient is treated with IV penicillin G 20 million units daily and scheduled for transurethral resection of the prostate (TURP) with biopsy. He undergoes a TURP without complications. Prostate chip pathology is positive for acute and chronic inflammation with eosinophilia and gangrenous necrotic foci without evidence of malignancy. The patient completes a 6-week course of IV penicillin G without complication, and his mentation, perineal pain, and other clinical parameters return to baseline.

Discussion

An emphysematous prostatic abscess (EPA) is an uncommon condition first described in 1983, with limited cases reported in the literature. EPA is an inflammatory condition where gas and purulent exudate form within the prostate gland. Before antibiotics were readily available, mortality reached 30%, and the causative agent was Neisseria gonorrhea.¹ Enterobacter is the most reported pathogen worldwide; mortality ranges from 3-18%.¹ Another review found Klebsiella to be the highest causative agent in Asia.² Studies also attribute EPA to Candida spp., Proteus spp., and Citrobacter spp.2 Despite treatment, a review of 12 patients observed a 25% mortality rate.²

Risks for EPA include diabetes mellitus, urinary retention, recurrent urinary tract infections, and the use of urethral instruments like catheters or various therapeutic devices.² A prior history of prostate cancer, as well as systemic diseases like cirrhosis, post-renal transplant status, and alcoholism, may influence EPA development.

EPA can also present with nonspecific symptoms; reported cases include patients presenting with dysuria, increased frequency, urgency, fever, urinary retention, perineal pain, lower abdominal pain, and general malaise.³ Our differential diagnosis included iatrogenic air accumulation due to urethral instrumentation, emphysematous cystitis, emphysematous pyelonephritis, and infected prostate cancer tumor. Potential misdiagnoses may settle on prostatitis or bacteremia, but these fail to appreciate the aggressive clinical behavior of patients with an emphysematous prostatic abscess.

EPA presentations are challenging to diagnose and differentiate from other conditions. In a review of 12 reported cases, all patients received a plain film of the kidney, ureter, and bladder. Still, nonspecific findings led to difficulty in differentiating EPAs from other prostatic pathologies.² CT scans that show gas formation and abscess are considered the first-line diagnostic tool.⁴ Imaging helped establish the diagnosis of EPA in our patient.

EPA patients are commonly treated with TURPs, which require caution due to the risk of a high-pressure system propelling bacteria into the systemic bloodstream. Aspiration under ultrasound guidance can be performed but may be difficult due to the ultrasound wave reflection from the gas and interference of shadows from air and calcifications.² Surgical drainage of abscesses is critical for treatment. In prior published articles, antibiotic combinations included either a third-generation cephalosporin or quinolone alone or with metronidazole or gentamicin for 4-6 weeks.² We used IV penicillin G, which successfully treated his infection and added to the clinical base of potential therapies for EPA cases dependent on the identified pathogen and sensitivity.

While transurethral radiofrequency needle ablation (TUNA) is a treatment for benign prostatic hyperplasia treatment, EPA can be a rare complication. After this procedure, prostatic tissue undergoes edema, hemorrhage, and coagulation necrosis of smooth muscle, eventually obliterating the blood vessel lumina and transitioning to hemorrhagic necrosis.⁵ While rare, the potential for an EPA could be considered when performing TUNAs.

In conclusion, EPA cases are uncommon, serious infections caused by various bacteria that can cause high mortality if they are not quickly diagnosed and treated. Due to nonspecific symptoms, SGIM members should maintain a high index of suspicion for EPA in patients with known risk factors like diabetes or presenting with nonspecific symptoms discussed in prior cases, such as dysuria, increased frequency, fever, and malaise. CT scan and ultrasound can assist in making the diagnosis. Prompt diagnosis leading to surgical drainage and systemic antibiotics are necessary for treatment and improved morbidity and mortality. Future research could describe long-term sequelae and outcomes of patients with this clinical entity.

SGIM Forum clinicians should know that male patients presenting with symptoms of a UTI and perineal pain could have prostatitis. For patients with signs concerning for sepsis, clinicians should have a low threshold for obtaining clinical imaging to confirm the diagnosis of prostatitis and the presence or absence of air in the prostate gland. Most patients do not have long-term sequelae with appropriate treatment for their infection.