Paraspinal Mass in a Seven-Year-Old Girl

A 7-year-old Inuit girl was seen by a pediatrician with a 1-week history of mild pain and swelling in the right upper back. The child was otherwise well, and there was no history of trauma to the area. There was mild tenderness and swelling of the involved area, but no mass was palpable and the remainder of the physical examination was normal. The diagnosis was not clear, so no treatment was prescribed. During the subsequent 2 weeks, a discrete mass became apparent at the site. Low grade fever was reported but not documented. The child had a history of poor dentition and recurrent episodes of tonsillitis. An elective tonsillectomy had been canceled 3 weeks before the onset of the back pain because of iron deficiency anemia. Right upper and right lower lobe pneumonia was diagnosed on chest radiograph 3 weeks before the onset of the back pain and had been treated with oral cefuroxime for 7 days. The child lived with her grandparents, who were reported to be currently healthy. The grandfather had been treated for pulmonary tuberculosis in 1959. The grandmother had a positive Mantoux test in 1967, but a normal chest radiograph was taken 6 months before the onset of the child's back pain. Physical examination on admission revealed a developmentally normal Aboriginal girl in no distress. Temperature was 37.8°C, pulse 128 beats/min, respiratory rate 24 breaths/min, blood pressure 90/53 mm Hg and oxygen saturation 98% in room air. Weight was 22.3 kg (50th percentile), and height was 116.5 cm (10-25th percentile). Dental examination revealed multiple carious primary teeth and delayed dental developmental with missing molars. There were no clinical signs of pneumonia. A firm and minimally tender mass was apparent in the right paraspinal region below the scapula, and measured ∼5 × 7 cm. The remainder of the physical examination was normal. Hematologic studies revealed a white blood cell count of 10,200/mm3 with 73% neutrophils, 17% lymphocytes, 7% monocytes and 3% eosinophils. Hemoglobin was 11.6 g/dl, and platelet count was 632,000/mm3. Liver function tests and serum bilirubin, total protein, albumin, phosphorus, magnesium, calcium and creatinine were all normal. Mantoux test was nonreactive. Chest radiograph on admission revealed right lower lobe consolidation. Ultrasound of the mass on the back showed a hyperechoic lesion within the erector spinae muscle with possible microlithiases, and the presumptive diagnosis was of a hemangioma. Computerized tomography of the chest confirmed the presence of an inhomogeneous soft tissue mass measuring ∼6.1 × 2.8 × 20.0 cm arising within the right erector spinae muscle with a possible area of necrosis in the inferior portion. The lesion appeared to be contiguous with an irregular opacity within the posterior segment of the right upper lobe and superior and posterior segments of the right lower lobe. The right 5th and 7th ribs were thickened, whereas periosteal new bone formation was noted in the right 6th rib. A biopsy of the back mass revealed the diagnosis. For denouement, see p. 478. Denouement Continued from p. 475 The surgeon described the presence of chest wall edema and a necrotic abscess cavity that extended from to the scapula to the chest wall. A drain was left in place for 3 days. Mixed inflammatory exudates with necrotic skeletal muscle and fat and Actinomyces-like organisms were identified on pathology. There were no granulomata and no malignant cells. Actinomyces israelii, Actinobacillus actinomycetemcomitans and Fusobacterium species were isolated from bacterial cultures of the abscess material. Fungal and mycobacterial stains and cultures of the abscess fluid were negative. This child had empyema necessitatis (extension of suppuration to the chest wall from the lung parenchyma or from the pleural space) based on her computerized tomographic scan findings and consistent with the organisms that were isolated. Empyema necessitatis is most commonly caused by tuberculosis or actinomycosis but has also been described with pyogenic bacteria.1 Despite growth of multiple organisms, we believe that A. israelii was the primary pathogen responsible for our patient's pulmonary actinomycosis with extension to the chest wall. A. israelii is a slow growing, microaerophilic, filamentous, Gram-positive bacterium that can be normal flora in the periodontal pockets, dental plaque, carious teeth, tonsillar crypts, intestine and female genital tract.2 Isolation of other organisms such as A. actinomycetemcomitans, Eikenella corrodens, Fusobacterium, Bacteroides, Capnocytophaga, Staphylococcus, Streptococcus and Enterobacteriaceae with Actinomyces is very common,3 but the role of these organisms in the pathogenesis of actinomycosis is not clear. Antimicrobials directed at Actinomyces alone are usually curative.4 Actinomycosis is an indolent, slowly progressive granulomatous infection that most commonly manifests as cervicofacial, thoracic, abdomino-pelvic or central nervous system disease. A. israelii is the most common etiologic agent in human disease, with Actinomyces gerencseriae, Actinomyces naeslundii, Actinomyces viscosus, Actinomyces odontolyticus, Actinomyces meyeri, Propionibacterium propionicum (formerly Arachnia propionica and Actinomyces propionicus) and Bifidobacterium dentium all being implicated.5 The differential diagnosis often includes tuberculosis, malignancy and nocardiosis. In our case, tuberculosis was considered because of the exposure history, and a malignancy was considered because of the presence of an enlarging mass with minimal evidence of inflammation in a well child. There were 46 case reports of pediatric thoracic actinomycosis in the English language literature from 1975 to 2000.6 Like our case, 56% presented with a mass. Cough and chest pain are often present,6 but fever and weight loss can be the only manifestations.7 Extension to the chest wall with the development of a draining mass or sinus occurred in 11% of the case reports6 and is highly suggestive of actinomycosis when present.3 Thoracic involvement can occur from direct extension of cervicofacial or abdominal disease, but most cases are presumed to be secondary to aspiration of organisms from the oropharynx. Most cases occur in previously well children such as our patient who have no risk factors for aspiration (anatomic abnormalities of the palate or esophagus, neurologic dysphagia or gastroesophageal reflux disease).8 However, there is increasing recognition that even healthy individuals can aspirate oropharyngeal secretions during sleep,8 and a high concentration of A. israelii in these secretions secondary to poor dental hygiene may have predisposed our patient to aspiration pneumonia. Isolation of organisms is the ideal way to confirm the diagnosis of actinomycosis but is often not achieved because of the fastidious growth requirements of these organisms. On Gram staining, Actinomyces spp. can be confused with Nocardia. Histologic identification of organisms within sulfur granules is said to be pathognomonic for actinomycosis by some sources,7 but other sources report that sulfur granules can also occur with nocardiosis, chromomycosis, eumycetoma and botryomycosis.4 Sulfur granules are not a universal finding in actinomycosis4,7 and were not present in our case. Several months of antimicrobial therapy in combination with surgical debridement of infected tissue (when possible) is the traditional treatment of actinomycosis. Penicillin remains the initial treatment of choice for actinomycosis, although resistance can occur. Macrolides, clindamycin and tetracyclines are suitable alternatives.9 Some sources recommend use of amoxicillin/clavulanate to cover possible copathogens.9 Cefuroxime would not be expected to be effective, which explains why our patient's pneumonia did not resolve with the initial course of antibiotics. There are an increasing number of case reports of cure of actinomycosis at all sites with 6 weeks or less of antimicrobials.6,10 Although all previous case reports but 1 of thoracic actinomycosis were treated with intravenous antibiotics initially,6 we chose to treat our patient with 6 months of oral amoxicillin/clavulanate therapy given that she had a thorough debridement and was clinically well. Penicillin alone probably would have been adequate, but we chose to cover for other likely causes of aspiration pneumonia as she had such extensive disease and lived in a very remote community where follow-up is problematic. She remains well 1 month after discontinuation of this antibiotic.

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