Fusobacterium Necrophorum Mediastinal Abscess Presenting As an Anterior Chest Wall Mass in a Child: A Case Report

Introduction

Fusobacterium infections in children are quite rare. Infections caused by Fusobactrium sp. have been associated with Lemierre’s syndrome, which is also known as necrobacillosis and postanginal sepsis. Lemierre’s syndrome, which is mainly observed in adolescents and adults, is a suppurative oropharyngeal infection that is associated with Fusobacterium necrophorum bacteremia and thrombophlebitis of the internal jugular vein and subsequent metastatic foci of infection.1 We report a case of an anterior mediastinal abscess due to Vusobacterium necrophorum in a child.

Patient Report

The patient was a 7-year-old, previously healthy, African- American, female who presented with a 2-week history of right chest wall pain followed by a 3-day history of fever to 101.8F. Six days before admission, she was evaluated by her primary care physician for the chest wall pain and fever; no abnormal findings were noted on physical examination of the oropharynx and chest. She was diagnosed with a viral illness; acetaminophen and ibuprofen were prescribed for relief of symptoms. Four days before admission, she was evaluated at a local emergency room for persistent right chest wall pain just above the right areola. At this time, the physical examination was significant for swelling over the right chest wall, but with no other physical abnormalities. She was diagnosed with presumed cat scratch disease and given a prescription for azithromycin; this prescription was not filled by her mother. Her symptoms persisted and she was again evaluated by her physician, who performed a chest radiograph. The radiographie findings were significant for a mass in the anterior mediastinum with no other parenchymal pulmonary or bony abnormalities. The patient was then admitted to the local hospital for further work-up.

A chest computerized tomogram (CT) scan revealed a large anterior mediastinal mass, which extended into the right hemithorax. A whole- body 18-fluoro-2-deoxyglucuse (FDG) pusiuun emission tomography (PET)-CT scan revealed hypermetabolic activity within the anterior mediastinal mass extending through the right anterior chest wall with enlargement of the right pectoralis muscle; no other areas of abnormal uptake in the neck, chest, abdomen, or pelvis were seen. An FDG PET-CT scan is a radiopharmaceutical study that functions at the molecular level and is known to show increased uptake in areas of neoplastic disease and inflammation.

The patient was then transferred to the University of South Alabama Children’s and Women’s Hospital, where an excisional biopsy of the anterior mediastinal mass was performed along with a bone marrow aspirate and biopsy. Before the biopsies, the patient was empirically treated with ce(epime administered intravenously. On hematoxylin-and-eosin-stained sections of the mediastinal biopsy specimens, the mass was composed of an abscess with dense neutrophilic infiltrates surrounding multiple, irregularly ovoid granules. On special stains, the granules were composed of delicate, branched filaments and spores. The filaments were positive on Brown gram, Gomori methenamine silver, and periodic acid Schiff with diastase stains (Figure 1). The filaments were negative on Zhiel- Neelsen stain. The bone marrow biopsy and aspirate revealed reactive changes, including mild hypocellularity for the patient’s age (60%) with trilineage hematopoiesis, and minimal plasmacytosis (5%). Examination of the peripheral blood smear revealed a normocytic normochromic anemia (10.3 g/dL), leukocytosis (14,900/cm) with netitrophilia (78%) and thrombocytosis (543,000/cm). There was no evidence of malignancy. Pos topera lively, intravenous ampicillin and metronidazole were started pending culture results, and a peripherally inserted central catheter was placed in the right antecubital vein for longterm intravenous antibiotics.

Figure 1. Dense neutrophilic infiltrates surround granules composed of delicate, branched filaments (inset). H&E, 200x; inset GMS 1000x.

Cultures from the mediastinal mass yielded Fusobacterium necrophorum, and intravenous penicillin and metronidazole were started as ampicillin and cefepime were discontinued. Blood cultures were negative for any bacterial pathogens. The patient then received 6 weeks of intravenous antibiotics followed by 2 weeks of oral clindamycin. Follow-up CT scan of the chest obtained 6 months later revealed resolution of the anterior mediastinal abscess.

Discussion

Fusobaclerium necrophorum infections that have been reported in children and adolescents include the following: Lemierre’s syndrome, meningitis, osteomyelitis, hepatic abscess, and septicemia.2-7 Lemierre’s syndrome was first described by Andre Lemierre, who observed septicemia in 20 patients caused by anaerobic infection of the tonsillar or peritonsillar region.1 Pathogenesis of this syndrome has been postulated to be secondary to the unique anatomy of the lateral pharyngeal space, which allows invasion of the infection into the jugular vein either by direct extension or by lymphatic and/or hematogeiious spread from the peritonsillar vessels.8 Septic emboli may then spread from the internal jugular vein to other foci of infection. F. necrophorum is the most common bacterium isolated from the blood stream in patients with Lemierre’s syndrome; other bacteria that have been isolated include the following: Bacteroides, Streptococcus, Lactobacillus sp., and other Fusobacterium sp.

To the authors’ knowledge this is the first pediatric case of mediastinal abscess due to F. necrophorum. Whether this was the primary site of infection or a metastatic focus from an occult primary infection (as in Lemierre’s syndrome) in our patient is unclear. Also unclear is whether the overall number of infections due to F. necrophorum is increasing. Over a 7-year period investigators at a children’s hospital found 1 case of F. necrophorum isolated between 1996 and 1999, but 5 cases between 2000 and 2001, and 5 cases between 2001 and 2002.2 A similar trend was noted in Denmark, where 16 cases were noted between 1990 and 1992, but 33 cases were observed between 1992 and 1995.9

Infections caused by F. necrophorum are diagnosed by tissue culture. Cervical color Doppler ultrasonography reportedly evaluates the extent of the internal jugular thromboses, which can also be detected by high-resolution computerized tomography.10

Treatment of F. necrophorum infections involves administration of intravenous antibiotics. With the advent of antibiotic therapy, the mortality rate has decreased to less than 20%. F. necrophorum is a gram-negative anaerobe, which is usually susceptible to penicillin, metronidazole, clindamycin, and chloramphenicol. However, there have been reports of increasing resistance of Fusobacterium sp. to penicillin, ciprofloxacin, and clindamycin.11 Various other agents, such as macrolides, including azithromycin and second- and third- generation cephalosporins, lack activity against F. necrophorum. Prompt surgical drainage of abscesses along with debridement of infected material is also necessary. In a recent report on Lemierre’s syndrome in children, development of Lemierre’s syndrome was halted when 4 of 8 patients with tonsillar abscesses caused by F. necrophorum underwent tonsillectomy with short-course antibiotic therapy.2 This report also found that in their practice area, pediatricians had decreased their prescription of antibiotics for pharyngitis. These authors postulated that this reduction in antibiotic prescriptions may have contributed to the increase in Lemierre’s syndrome cases in their area.

In cases of suppurative jugular thrombophlebitis the recommended treatment includes drainage of the lateral pharyngeal space and ligation of the internal jugular vein.12

It is still unclear why our patient had this mediastinal abscess due to F. necrophorum or whether this was a case of Lemierre’s syndrome. No other primary sites of the infection were noted clinically or by special imaging. However, this case emphasizes not only the importance of vigilance for the possibility of anaerobic infections when a patient presents with an anterior mediastinal mass but also the occurrence of Fusobacterium sp. infections in children.

REFERENCES

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9. Hagelskjaer LH, Prag J, Malczynski J, Kristensen JH. Incidence and clinical epidemiology of necrobacillosis, including Lemierre’s syndrome in Denmark 1990-1995. Eur J Clin Microbiol Infect Dis. 1998;17:561-565.

10. Gudinchet F, Maeder P, Neveceral P, Schnyder P. Lemierre’ syndrome in children: high-resolution CT and color Doppler sonography patterns. Chest. 1997;112:271-273.

11. Aldridge K, Ashrraft D, Cambre K, et al. Multicenter survey of the changing in vitro antimicrobial susceptibilities of clinical isolates of Bacteroides fragilis group, Prevotella, Fusobarterium, Porphyromonas, and Peptostreptococcus species. Antimicrob Agents Chemother. 2001;45:1238-1243.

12. Chow A. Suppurative jugular thrombophlebitis and carotid artery erosion. In: Mandell D, ed. Bennett’s Principles and Practice of infectious Diseases. 5th ed. Philadelphia, PA: Churchill Livingstone; 2000:696.

Mary Mancao, MD1

Elizabeth Manci, MD2

Maria Figarola, MD3

Benjamin Estrada, MD1

Clin Pediatr. 2005;44:73-75

Departments of 1Pediatrics, 2Pathology, and 3Radiology, University of South Alabama College of Medicine, Mobile, AL.

Reprint requests and correspondence to: Mary Mancao, MD, University of South Alabama College of Medicine, Departments of Pediatrics, Pathology, and Radiology, 1504 Springhill Avenue, Room 5224, Mobile, AL 36604.

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Copyright Westminster Publications, Inc. Jan/Feb 2005