Unusual Case of Occult Brucella Osteomyelitis in the Skull Detected by Bone Scintigraphy

Abstract

Brucellosis is a worldwide infectious disease of animals that can be transmitted to humans. Osteoarticular involvement is the most common complication of brucellosis. A 47-year-old man, who was a stockbreeder, complained of myalgia with fever and chills for 2 weeks. The serology titers and blood cultures for brucellosis were positive. Bone scintigraphy demonstrated a focally increased uptake in the left supraorbital area. Plain radiographs showed an osteolytic lesion, and an MRI revealed signal abnormalities in the corresponding site. We present an unususal case of occult Brucella osteomyelitis in the frontal bone of the skull detected by bone scintigraphy.

Brucellosis is a worldwide infectious disease of animals that can be transmitted to humans. The disease usually spreads to humans by direct contact with infected animals, by ingestion of unpasteurized milk or milk products, through cuts and abrasions, or by inhalation of aerosols. It can affect individuals of all ages. Its clinical features are not disease-specific and may be mild, self-limiting, or severe. Hematogenous dissemination is followed by localization of bacteria within the reticuloendothelial system, such as the liver, spleen, and bone marrow. Once localized, Brucella spp. induce a granulomatous reaction [1]. Although brucellosis often results in complications in various parts of the body, osteoarticular involvement is the most common complication and includes arthritis, sacroiliitis, spondylitis, and osteomyelitis. Most reports of Brucella osteomyelitis have involved the spine [2–6] or the long bones [2, 3]. Other rare sites, such as the calcaneus [7, 8], middle phalanges of the fingers [9], sternum [10], carpal bones [11], tarsal bone, ribs, clavicle, and pelvic bone [12] also have been described. Involvement of the skull is considered to be extremely rare. It was reported that a 14-year-old boy with an erythematous, non-tender mass over the left mid-forehead area had Brucella osteomyelitis of the left frontal bone with an epidural abscess [13]. However, our patient had no symptoms and only osteomyelitis in the frontal bone.

Bone scintigraphy has been reported to be a highly sensitive method for the detection of osteoarticular brucellosis and should be routinely used in screening for asymptomatic occult lesion in patients with brucellosis [2–5]. We present an unusual case of occult Brucella ostomyelitis in the frontal bone of the skull detected by bone scintigraphy (Figs. 1, 2, 3).

Fig. 1.

A 47-year-old man had a 2-week history of myalgia with fever and chills. He was a stockbreeder. The physical examination was unremarkable. The serology titers for brucellosis were elevated. A blood culture grew Brucella spp. The erythrocyte sedimentation rate (23 mm/h), serum C-reactive protein (18.9 mg/L), and alanine aminotransferase (50 IU/L) were elevated. The other laboratory results were normal. Tc-99 m MDP bone scintigraphy was performed for the evaluation of osteoarticular complications of brucellosis and demonstrated a focally increased tracer uptake in the left supraorbital area (arrows). Plain radiographs and a magnetic resonance image (MRI) were performed to evaluate the areas showing abnormal uptake

Fig. 2.

Plain radiograph of the skull showed a radiolucent osteolytic lesion in the left supraorbital area

Fig. 3.

MRI of the brain demonstrated an area of a low signal intensity in the frontal bone on T1-weighted image (WI), b high signal on T2-WI, and c marginal enhancement on contrast enhanced T1-WI. These results were suggestive of a bone abscess (arrows). The patient underwent a craniotomy. The biopsy confirmed a chronic granulomatous infection caused by Brucella spp. He received antibiotic therapy