Soft tissue mass of the chest wall as the sole manifestation of brucellosis in a 7-year-old boy

Abstract

We report the case of a child who presented with a subcutaneous mass on the left side of the chest wall of one month's duration. The mass was painful and increasing in size over time. He had a history of weight loss and a decrease in appetite, but no history of fever or trauma. He had ingested raw camel milk, but had no history of contact with animals. He was diagnosed by the standard tube agglutination titer and tissue culture for brucellosis, treated with surgery and three months of antibrucella antibiotics. The report includes a brief review of the current pediatric literature to familiarize pediatricians with this uncommon presentation.

Human brucellosis has a serious medical impact worldwide. The disease is caused by small, gram-negative, intracellular coccobacilli that are oxidase- and urease- positive. Transmission to humans occurs through the consumption of infected, unpasteurized animal-milk products, or through direct contact with infected animal parts (such as the animal placenta by inoculation through ruptures of the skin and mucous membranes), and rarely through the inhalation of infected aerosolized particles. Airborne transmission of brucellosis has been studied as a biologic weapon. It is a systemic disease that can infect any organ system, causing different clinical manifestations. Practically every organ and system of the human body can be affected in brucellosis—a fact that underscores the importance of including brucellosis in the differential diagnosis in areas of endemic disease, even if clinical features are not entirely compatible.

The serum agglutination test remains the most popular diagnostic tool for brucellosis. Titers above 1:160 are considered diagnostic in conjunction with a compatible clinical presentation. However, in areas where brucellosis is an endemic disease, using a titer of 1:320 as diagnostic may be more specific. A high prevalence in certain geographic areas is well recognized, although largely under-diagnosed. Human brucellosis affects all age groups. Childhood brucellosis generally exhibits a more benign course in terms of the rate and severity of complications and the response to treatment, but isolated subcutaneous tissue involvement in children is rare.

CASE

A 7-year-old boy was referred to King Faisal Specialist Hospital and Research Centre with a complaint of a chest wall mass of 1-month duration to rule out malignancy. This mass was painful and increasing in size. He had a history of weight loss of about 1 kg and a decrease in appetite over the previous 1 month, but no history of fever or trauma. He had ingested raw camel milk, but had no history of contact with animals. Clinically he was comfortable, oriented, afebrile, not in pain or respiratory distress, with average body weight. His clinical examination was unremarkable except for a mass on the left chest wall, measuring about 54 cm, tender, firm, not fluctuating, mobile, with no skin changes. His laboratory workup was as follows: white blood cell count was 8.8Χ10⁹/L, lymphocytes were 53%, absolute neutrophil was 42%, hemoglobin level was 9.9 g/dL and the platelet count was 332Χ10⁹/L. The erythrocyte sedimentation rate was 54 mm/h. Alkaline phosphatase was 177 IU/L. CT of the chest revealed a left chest wall mass with a layering effect (Figure 1) with a subpleural mass retrosternally (Figure 2).

Figure 1.

CT scan of the chest revealed a left chest wall mass with layering effects.

Figure 2.

CT scan of the chest three months after treatment showed complete resolution of the mass.

During surgery, a subfascial swelling filled with a whitish fluid with a small cavity was found. Histopathological examination showed mixed inflammation with histiocytic/granulomatous reaction with a foci of necrosis. Brucella serology showed that the standard tube agglutination titer (STAT) was more than 20 480 at first; 2-mercaptoethanol was more than 1:20 480. Fastidious tissue culture was reported as gram-negative coccobacilli identified as Brucella species. A peripheral blood culture for fastidious organism was discontinued at day 2 of incubation because of growth of coagulase-negative staphylococci, which was considered a contaminant. The patient was started on antibrucella treatment including trimethoprim/sulfamethoxazole of standard formulation (80 mg trimethoprim/400 mg sulfamethoxazole) 2 tablets per day and rifampicin 20 mg/kg/d for 3 months.

Three months later, the patient was seen in the clinic in good condition; a repeat STAT was 1:5120. Repeated CT chest 6 months after the surgery was completely normal.

DISCUSSION

Brucellosis is a zoonotic disease that causes health problems in many areas worldwide,¹ especially in the Mediterranean basin, Arabian Peninsula, Indian subcontinent and parts of Mexico and Central and South America.² Humans are accidental hosts. It is an occupational risk in adults working with livestock, while in children it is mainly foodborne.³ It is a systemic disease that can affect any part of the body,⁴,⁵ with nonspecific complaints, with a paucity of physical findings, and with an onset that can be insidious or acute. Symptoms begin 2 to 4 weeks after exposure—mainly fever, sweating, malaise, lethargy, anorexia and joint pains.^6–14

Refusal to eat or to bear weight, failure to thrive and lassitude are the common complaints in young children. Brucellosis is a chronic granulomatous disease in which multisystem manifestations are well recognized. Although a case of brucellosis presenting with mass formation suggestive of tumor in soft tissue has been reported recently in an adult,¹⁵ to the best our knowledge this is the first reported pediatric case of an isolated subcutaneous tissue mass as the sole manifestation of brucellosis, an unusual presentation of brucellosis in a child. In endemic areas, brucellosis should always be considered in the differential diagnosis of subcutaneous tissue mass even without any other constitutional symptoms.