James S Bingham

Evaluation of (18)fluorodeoxyglucose positron emission tomography ((18)FDG PET) in the detection of malignant peripheral nerve sheath tumours arising from within plexiform neurofibromas in neurofibromatosis 1

OBJECTIVES The ability of 18fluorodeoxyglucose positron emission tomography (18FDG PET) to detect malignant change in plexiform neurofibromas from patients with neurofibromatosis 1 (NF1) was evaluated. METHODS Eighteen NF1 patients who presented with pain, increase in size, or neurological deficit associated with a plexiform neurofibroma were assessed. Magnetic resonance imaging determined the site and extent of the lesion. Qualitative18FDG PET was performed and the standard uptake value (SUV) measured the regional glucose metabolism. Histological confirmation of the diagnosis was obtained in 10 patients. RESULTS Twenty three plexiform neurofibromas were detected in 18 patients. Seven malignant peripheral nerve sheath tumours, four high grade and three low grade tumours, occurred in five patients. In one patient the clinical and radiological characteristics of the tumour suggested malignancy, but histology was inconclusive. Fifteen benign plexiform neurofibromas were identified in 12 patients and these findings were confirmed histologically in five lesions from four patients. Ten plexiform neurofibromas occurring in eight patients were considered benign on18FDG PET and the patients did not undergo surgery. They remained stable or their symptoms improved on clinical follow up (median 9 months). The results of qualitative 18FDG PET were interpreted as indicating that 13 plexiform neurofibromas were benign and 10 were malignant. No malignant tumours were classified as benign, but two benign tumours were reported as malignant. The SUV was calculated for 20 tumours and was significantly higher in five malignant tumours 5.4 (SD 2.4), than in 15 benign tumours 1.54 (SD 0.7), p=0.002. There was an overlap between benign and malignant tumours in the SUV range 2.7–3.3. CONCLUSIONS 18FDG PET is helpful in determining malignant change in plexiform neurofibromas in NF1. Increased separation between benign and malignant lesions could be obtained by calculating the SUV at about 200 minutes after injection of 18FDG, when the peak activity concentration is obtained in malignant tumours.

MRI in neurofibromatosis 1. The nature and evolution of increased intensity T2 weighted lesions and their relationship to intellectual impairment.

Thirty eight patients with neurofibromatosis 1 (NF1) had neurological examinations, intellectual assessments and MRI scans. Increased intensity lesions on T2 weighted images were found in 13 patients. These abnormalities were more common in patients aged under 18 years. The lesions occurred predominantly in the basal ganglia, brainstem and cerebellum, and were multiple in 11 patients. They did not produce symptoms or neurological deficit in any patient and did not enhance with gadolinium-meglumine-triamine-pentaacetic acid contrast medium (Gd-DTPA). In 2 patients, however, the abnormalities exerted mass effect distorting the brain and in 3 patients they occurred in conjunction with known gliomas. The lesions remained unchanged over a three year follow up period. The nature of the lesions is uncertain but the fact that they may produce mass effect and occur in association with gliomas suggests that they have malignant potential. There was no correlation between the presence of these abnormalities and intellectual impairment.

Can FDG PET be used to successfully direct preoperative biopsy of soft tissue tumours

Magnetic resonance imaging (MRI) has been the most useful tool in the anatomical definition of soft tissue sarcoma, although there remains the problem of defining the lesions as benign or malignant. The management of such lesions requires biopsy prior to surgical resection. If the most malignant area could be defined more accurately, then this area could be targeted for biopsy. Fluorodeoxyglucose positron emission tomography (FDG PET) has been found to be useful in identifying malignancy and variations in grade in soft tissue masses. The aim of this study was to assess the use of FDG PET scanning with or without co-registered MRI to indicate the most appropriate biopsy site. Twenty consecutive patients presented with soft tissue masses with clinical signs of malignancy. All patients underwent MRI and FDG PET scanning and the two images were co-registered. A biopsy site that was the most likely to be malignant was defined on the PET scan. All patients underwent an initial biopsy and then complete surgical resection of the mass. The histological results from the mass were compared with those from the biopsy specimen obtained from the site suggested by the PET scan. In malignant masses the biopsy site suggested by the FDG PET scan was found to be representative of the most malignant site on the whole mass histology. Benign lesions had low or no FDG uptake. In no case did the co-registered image add significantly to the appropriate biopsy site. FDG PET can be used to appropriately direct biopsy in soft tissue sarcoma and potentially may lead to computed tomography/MRI directed outpatient biopsy prior to definitive treatment.

Persistence of Pseudomonas aeruginosa strains in respiratory infection in AIDS patients.

Objectives:To establish the clinical pattern of Pseudomonas aeruginosa respiratory infections in HIV-seropositive patients and to determine whether repeated isolation of the organism represents reinfection or recurrence and to assess whether common source, nosocomial infection occurred. Design and methods:Evaluation of the clinical pattern of P. aeruginosa respiratory infections by case note review and epidemiological characterization of P. aeruginosa by serotype determination and XbaI DNA macrorestriction analysis. Serum sensitivity testing of strains was performed to further define phenotypic characteristics of the isolated organisms. Results:Seventy-three per cent (29 out of 40) of individuals had P. aeruginosa isolated on two or more occasions in the setting of clinical respiratory infection. Overall, 85% had evidence of P. aeruginosa to within 2 months of study completion or death. Epidemiological characterization revealed persistence of unique single strains in 93% of individuals where multiple isolates were available for testing, whereas only two patients harboured a common strain. The serotype distribution of strains was similar to that reported from non-HIV-positive patients. Conclusions:Once established, eradication of P. aeruginosa from the respiratory tract of HIV-seropositive individuals with advanced immunosuppression is problematic and a chronic infective state appears common. There was no evidence of nosocomial transmission. Serotype loss and development of sensitivity to normal human serum were both observed and were highly correlated. This represents truncation of O-antigenic lipopolysaccharide on the cell surface of P. aeruginosa and may reflect progression to phenotypes commonly associated with chronic infection in other clinical settings such as cystic fibrosis.

Acetarsol pessaries in the treatment of metronidazole resistant Trichomonas vaginalis.

In 1960 metronidazole was shown to be the ® rst effective systemic treatment for Trichomonas vaginalis1. As most previous treatments were topical and largely ineffective, its introduction was a signi® cant development2. Since then metronidazole has remained the standard antimicrobial agent for the treatment of trichomonal infections. The ® rst published reports of metronidazole resistant organisms emerged in the late 1970s and early 1980s and, although well established now, the existence of resistance was at ® rst controversial3,4. Although T. vaginalis remains one of the most prevalent sexually transmitted diseases (STDs) worldwide the documentation of resistant organisms is relatively infrequent5,6. However, individual cases of metronidazole resistance are often dif® cult to treat, a problem compounded by the lack of evidence to support the use of alternative therapies. Although unlicensed, acetarsol pessaries have been available for the treatment of T. vaginalis for several decades and were the standard treatment for trichomonal infections prior to the advent of metronidazole7. Recently there has been interest in the use of acetarsol pessaries where metronidazole has been shown to be ineffective8,9. We report 4 cases of trichomonal infections seen at the Department of Genitourinary Medicine, Guy’s and St Thomas’ Hospitals, where repeated treatments with metronidazole have failed, and describe our experience in the use of acetarsol pessaries.

Female Genital Mutilation

Female genital mutilation is perhaps currently the most dangerous traditional practice in terms of health. An estimated 100 million women worldwide have undergone this procedure, most commonly performed between the ages of 4 and 10 years old by a traditional birth attendant. In one study, acute complications occurred in 39% of procedures. Hemorrhage and infection leading to gangrene, septicemia, or tetanus are the main causes of mortality. Late complications are estimated to occur in 37% of women. Chronic pelvic inflammatory disease and dysmenorrhea occur in 14-65%. Persistence of female genital mutilation is based, in part, on cultural beliefs about women, a perceived need to reduce sexual desire, and assurance of virginity and marriageability. Women who do not comply face social ostracism. In 1982, the World Health Organization recommended that female genital mutilation should not be carried out by any health professional under any circumstances. Although legislation outlawing the practice is important, it may be unenforceable in many areas. Key to the eradication of this practice are attitudinal changes through the education of both men and women and improvements in womens status. Female genital mutilation is a cultural practice without religious foundation or justification despite the misconception and misinterpretation to the contrary on the part of the victims and perpetrators.

Disseminated candidiasis in two HIV-positive intravenous drug users.

The management of HIV-positive intravenous drug users (IVDU)presents several challenges to health care workers. Although progression of HIV disease in IVDUs appears similar to that in other risk groups, intravenous drug use itself can give rise to symptoms and signs difficult to distinguish from some of those arising as a result of HIV infection. In addition, the clinical course may be punctuated by local and systemic complications of intravenous injection, the management of which, in common with HIV-negative drug users, may be further complicated by poor compliance with medication1. We present 2 patients attending a combined HIVIdrug maintenance clinic who presented with features of disseminated candidiasis, a syndrome which has been recognized increasingly in IVDUs over the last decade.