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).

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.

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.