February 2004

A 4-year-old boy was admitted to the hospital for evaluation and treatment of persistent rectal-area pain. His problem began about one week earlier with ill-defined pain in this area. Initially the pain was diagnosed as mild skin irritation and was treated with a topical cream. However, the pain worsened, and he was reevaluated with a complete physical, including a rectal exam (reported as normal), a complete blood count (CBC), urinalysis (UA) and acute abdominal X-ray series. At that time, the patient was diagnosed with constipation and given an enema, which produced relief of the pain. However, after he was sent home, his blood count returned revealing a white blood cell count of 24,900 with 87% granulocytes. His UA was normal. A phone call follow up that afternoon indicated that he was still doing well, however, that evening he returned with a reoccurrence of the pain. He was then admitted and had another abdominal x-ray series (figure 1), and subsequent abdominal/pelvic computed tomography (CT) scan (figures 2-4).

There had been no history of nausea, vomiting, diarrhea or constipation (even though the x-ray interpretation was positive for constipation). He did complain of some minor upper respiratory tract congestion with mild cough at this time.

His past medical history and review of systems was unremarkable. His family and social history was also normal with no history of abuse or accidental trauma. His immunizations were up to date.

Examination on admission revealed a low-grade fever (100.9° F). The other vital signs were normal, as was his examination.

What’s your diagnosis?

1. Tumor
2. Pilonidal cyst (abscess)
3. Perirectal abscess
4. Hemorroids

Answer

The answer is C, perirectal abscess. The plain film of the patient’s abdomen shown in figure 1 revealed that the distal end of the rectal air column was deviated toward the left, and the CT images showed a multi-loculated, right perirectal abscess. He was taken to the operating room, where under anesthesia, a digital examination revealed a firm mass in the right posterior-lateral aspect of the rectum. A needle aspiration produced yellowish pus and an incision and drainage procedure was performed, draining 15 cc to 20 cc of pus from the lesion. The aerobic culture grew a large amount of methicillin-resistant Staphylococcus aureus (MRSA). The anaerobic culture was negative.

The patient was initially treated with a combination of clindamycin and gentamicin, but upon learning the culture results gentamicin was discontinued. The sensitivities of the MRSA revealed clindamycin-sensitive but erythromycin-resistant. Therefore, a “D-test” was performed, which revealed no inducible resistance to the clindamycin. This issue has been discussed in a couple of previous issues of Infectious Diseases in Children (April 2003 and Nov. 2003). The patient was discharged home on oral clindamycin to finish his 10-day course of antibiotics.

His course represents the typical presentation of an intersphincteric space abscess — fever and a vague aching feeling in the rectal area that may take several days to come to diagnosis and may be temporarily relieved with defecation. Many report a purulent anal discharge from some spontaneous drainage. On examination, there may be external, perianal erythema in those with perianal infections, but if the infection is confined to the deeper spaces, there may be no external findings, as was the case in the patient presented. Lab tests are usually of little value, but of course, this patient had an elevated white blood cell count on his CBC. A pelvic CT scan, as shown, readily revealed the problem.

Perirectal abscesses have a 2:1 male predominance and can occur in a variety of locations in the perirectal tissues. Approximately half of the abscesses are perianal, with the next most common site being the intersphincteric space. The openings of various mucous-secreting anal glands near the anal crypts serve as ports-of-entry for the infecting organisms, setting the stage for infection when they become obstructed. Infection can then spread to various perirectal spaces. These infections are often polymicrobial, with various aerobic and anaerobic etiologies. The most common organisms isolated include common skin and bowel aerobes Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Proteus, and Bacteroides fragilis (the most common anaerobe). Therefore, initial empiric antibiotic therapy should cover these organisms pending culture results. A good combination would be clindamycin plus an aminoglycoside, like gentamicin. Of course, surgical drainage is essential, and is the only way to properly culture for the causative organism(s). Then medical therapy can usually be narrowed. Reoccurrence is seen in about one-third, usually in the same location.

Risk factors include immunosuppression, diabetes, inflammatory bowel disease, recent surgery and possibly steroid therapy. Complications may include fistula formation, bacteremia and sepsis (especially in immunocompromised patients). A particularly severe complication, seen mostly in adult men, usually with underlying diseases, is Fournier’s gangrene (FG), which is a severe, necrotizing infection of the perineum, especially the scrotum (figure 5). In about one-fifth of patients with FG, the underlying cause is a perirectal infection. The rest have other ports of entry. It also is usually a polymicrobial infection with group A streptococcus playing a greater role, probably in a synergistic fashion. As a form of necrotizing fasciitis, FG has a rapid progression, requiring urgent surgical debridement of necrotic tissue (figures 6-7) and broad-spectrum antibiotics. Some experts would recommend the same combination noted above, with perhaps a third antibiotic, such as an anti-pseudomonal penicillin. Diagnosis is visual, but a CT scan will reveal the extent of the infection, which may contain pockets of gas (figure 8). It is also important to treat any underlying condition, such as diabetes, in a patient with FG. I have never seen this condition in a child, but it is not unheard of.

The CT scan confirmed the diagnosis of perirectal abscess in the case presented, but certainly any mass may produce similar symptoms. Hemorrhoids would likely be seen on external inspection, and would not likely cause fever. A pilonidal cyst or abscess occurs over the sacral or coccyx area. A tumor would probably appear as a solid mass on CT scan, rather than a multi-loculated mass.

This case also demonstrates the difficulty in detecting a rectal mass by digital exam in a young child. It eluded detection from an experienced pediatrician and surgeon until he was under anesthesia. However, rectal exams should still be performed in any situation where rectal pathology might exist. Our gastroenterologists tell us that there are two reasons not to do a rectal exam — no rectum or no finger. I might add that cancer patients who are neutropenic are at increased risk of having these infections, but may not be able to mount enough of a response to produce an abscess. These patients are also at increased risk of Pseudomonas aeruginosa being the cause. Rectal examinations in these high-risk patients should be done with great care and caution or deferred because of the risk of bleeding and/or bacteremia.

Of interest, Jean Alfred Fournier (1832–1914) was a French dermatologist who specialized in venereal diseases, especially syphilis. He described the anterior bowing of the tibia (Fournier’s tibia) and the scaring of the mouth (Fournier’s sign) in congenital syphilis.

For more information:

• James H. Brien, DO, Pediatric Infectious Disease, Scott and White’s Children’s Health Center and Associate Professor of Pediatrics, Texas A&M University, College of Medicine, Temple, Texas. E-mail: jhbrien@aol.com.

References for perirectal abscess:

• www.emedicine.com/emerg/topic494.htm
• Roberts JR. Clinical Procedures in Emergency Medicine. 3rd ed. Philadelphia, Pa: W.B. Saunders; 1998.
• Ferri F. Ferri’s Clinical Advisor: Instant Diagnosis and Treatment. 6th ed. Philadelphia, Pa: Mosby; 2003.
• Marx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. Philadelphia, Pa: Mosby; 2002.
• Long SS. Principles and Practice of Pediatric Infectious Diseases. 2nd ed. Philadelphia, Pa: Churchill Livingstone; 2002.

References for Fournier’s gangrene:

• Morpurgo E, Galandiuk S. Fournier’s gangrene. Surg Clin North Am. 2003;82:1213-1224.
• Rakel RE, ed. Necrotizing fasciitis. Conn’s Current Therapy. 55th ed. Philadelphia, Pa: W.B. Saunders; 2003.
• Marx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. Philadelphia, Pa: Mosby; 2002.
• Uppot R, Levy H, Patel P. Case 54 Fournier gangrene. Radiology. 2001;226(1):115-117.
• Walsh PC, Vaughn ED. Campbell’s Urology. 8th ed. Philadelphia, Pa: W.B. Saunders; 2002.
• Santora T, Rukstalis D. Fournier gangrene. eMedicine. Oct. 2002.
• Namias N. Honey in the management of infections. Surg Infect. 2003;4(2):219-226.
• Nisbet AA, Thompson IM. Impact of diabetes mellitus on the presentation and outcome of Fournier’s gangrene. Urology.2002;60(5):775-779.
• Korhonen K. Hyperbaric oxygen therapy in acute necrotizing infections. With a special reference to the effects on tissue gas tensions. Ann Chir Gynaecol. 2000;89(Supp 214):7-36.
• Hollabaugh RS, Dmochowski RR, Hickerson WL, et al. Fournier’s gangrene: therapeutic impact of hyperbaric oxygen. Plastic Reconstr Surg. 1998;101(1):94-100.

• Additional reference: Dr. Itzhak Brook has a very nice, concise review of perirectal abscesses in children in his book, Pediatric Anaerobic Infections Diagnosis and Management (3rd ed. 2002;403-405). This is by far the single best reference on pediatric anaerobic infections I have found. It is published by Marcel Dekker and sells for about $195. It has about 600 pages packed with useful information.

Columnist acknowledgement:

• I would like to thank guest columnist Laura Wang, MD, for her work on this case presentation and discussion. I also would like to congratulate her on her marriage this month to Will Black, MD, also a senior pediatric resident at Scott & White. Finally, I would like to thank my son, James C. Brien, a fourth-year medical student at the Texas A&M University System Health Science Center College of Medicine for his work and contribution on the Fournier’s gangrene part of the discussion. He will be entering a urology residency this summer. — James H. Brien, DO