Langerhans cell histiocytosis (LCH) is an uncommon group of disorders affecting mainly children and young adults. In children, pulmonary involvement occurs mostly in the disseminated forms; isolated pulmonary lesions are unusual. A retrospective study was undertaken on a group of 42 children diagnosed with LCH over a 19-year period. Eight children (19 %) had radiological evidence of pulmonary involvement. The lung lesions were either present at the time of diagnosis or, when appearing during the course of the disease, always coinciding with exacerbation or recurrence of the disease in other sites. Lung involvement did not appear to be an unfavourable prognostic factor. However, the toxic effects of treatment on the lungs might lead to important pulmonary sequelae.

HistoryThe original description of a localized bone abscess dates from 1832 and is named after Sir Benjamin Collins Brodie, a surgeon in St. George's Hospital, London, United Kingdom (Fig. 1). He amputated the leg of a man who had intractable pain for a number of years. Unfortunately, the patient died due to the complications of the amputation. After macroscopic examination of the amputated limb, Brodie described the condition in the tibia as "a cavity the size of a walnut filled with dark-colored pus. The bone immediately surrounding the cavity was whiter and harder than the surrounding bone. The inner surface of the cavity appeared to be highly vascular" (1). PathogenesisA Brodie's abscess is a subtype of a subacute osteomyelitis. In a Brodie's abscess a situation develops where the bacteria and the host defenses are equally matched; the abscess is walled-off, minimizing the systemic response. An osseous infection can be caused by haematogenous spread of organisms to bone or by direct local invasion by bacteria. The organisms reach the bone from a disrupted site elsewhere in the body such as a skin pustule, furuncles, impetigo, infected blisters and burns, or secondary to an infection of another organ system (urogenital infections, enteritis, cholangitis or endocarditis).terial invasion, e.g. through penetrating wounds or postoperative infection. This route is most likely after contaminated soft tissue trauma, as well as in diabetic patients with plantar ulcers or in bedridden patients with decubitus ulcers (2). The causative organism is usually coagulase-positive Staphylo coccus (3). Other organisms encountered are Streptococcus B, in the newborn, Pseudomonas, which is more frequent in drug addicts than in the general population, and Infection has even been suggested to be the outcome of common events such as normally harmless daily teeth brushing. Often the infective focus is not identified. Direct spread to bone can occur from bac-JBR-BTR, 2010, 93: 81-86. Radiology plays an important role in the diagnosis of a Brodie's abscess, as can be difficult for a clinician to identify the disease using clinical information alone. A Brodie's abscess is clinically difficult to diagnose because patients typically have mild local symptoms, few or no constitutional symptoms, and near normal laboratory values. Furthermore, a Brodie's abscess may mimic various benign and malignant conditions, resulting in delayed diagnosis and treatment. The most frequently made incorrect diagnosis is that of a primary bone tumor. The present pictorial review summarizes imaging clues to the diagnosis of a Brodie's abscess, such as the serpentine sign on conventional radiographs and the penumbra sign seen on Magnetic Resonance (MR) images. A Brodie's abscess is difficult to diagnose, however, once diagnosed, it is a curable disease with a 100% cure rate. BRODIE'S ABSCESS REVISITED

CBCT detects significantly more small bone and joint fractures, in particular complex fractures, than CR. In the majority of cases, the clinical implication of the additionally detected fractures is limited, but in some patients (e.g., fracture-dislocations), the management is significantly influenced by these findings. As the radiation dose for CBCT substantially exceeds that of CR, we suggest adhering to CR as the first-line examination after small bone and joint trauma and keeping CBCT for patients with clinical-radiographic discordance or suspected complex fractures in need of further (preoperative) assessment.

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We present a 50-year-old man who was investigated for sensorineural hearing loss. On MRI of the brain superficial siderosis of the central nervous system was seen, while MRI of the spine revealed an ependymoma of the cauda equina. This case illustrates the importance of performing T2-weighted imaging of the brain and posterior fossa when sensorineural hearing loss is present. Spine imaging is mandatory when superficial siderosis of the brain is diagnosed without identification of a bleeding source in the brain.

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Our objective was to determine the visibility of the cisternal segment of the normal abducens nerve using a three-dimensional Fourier-Transform constructive interference in the steady state (3DFT-CISS) sequence. Its visibility was rated in 150 patients without clinical evidence of abducens nerve disturbance. Axial 1-mm 3DFT-CISS images were obtained (TR/TE 17/7 ms, flip angle 50 degrees, field of view 160 mm, matrix 256 x 256). The cisternal segment was seen in 79% of cases, bilaterally in 73% and unilaterally in 11% of cases; neither cisternal segment was seen in 16% of cases. Identification of Dorello's canal was often of help in detecting the point lateral to the dorsum sellae at which the nerve pierces the dura mater. Flow artifacts and vascular loops in the pontine cistern sometimes caused problems in interpretation. 3DFT-CISS MRI with 1-mm-thick sections can however be considered a reasonably reliable technique for showing the cisternal segment of the abducens nerve.

We prospectively studied 163 patients referred for MRI of the temporal bone. A presumed diagnosis was made using only one of three sequences: a single thick (12 mm) slice fast T2-sequence, 3D fourier transform constructive interference in steady state (3DFT-CISS) sequence and a gadolinium-enhanced T1-weighted sequence. The visibility of the cochlea, vestibule and superior, lateral and posterior semicircular canals of normal temporal bones was assessed on the T2-weighted images: they were almost always visible (98-100%), with exception of the superior semicircular canal, seen in only 35% of cases. The images were interpreted as abnormal in 34 patients (21%). Using only the fast T2-weighted, 3DFT-CISS and gadolinium-enhanced T1-weighted sequences a presumed false positive diagnosis was made in 5, 1 and 0 cases and a false negative diagnosis in 2, 2 and 4 cases respectively. The overall reliability of the thick-section fast T2-weighted images is limited. This study suggests that a combination of gadolinium-enhanced T1-weighted and 3DFT-CISS images can be considered the gold standard for temporal bone MRI and neither sequence performed separately is as accurate as both together.