Kasabach-Merritt phenomenon (KMP) is characterised by thrombocytopenia, microangiopathic haemolytic anaemia and consumptive coagulopathy that can lead to life-threatening bleeding, in the context of an enlarging vascular tumour (1). KMP usually develops in infancy and is associated with significant morbidity and mortality. Potentially fatal complications associated with KMP include haemorrhage, cardiac failure and invasion of vital structures by the lesion. The mortality rate is reported as high as 30% (2). The first case of KMP was reported in 1940 by Kasabach and Merritt, who described a case of consumptive coagulopathy associated with a hemangioma (3). However, it is now recognised that KMP is usually associated with Kaposiform hemangioendothelioma (KHE) and tufted angioma, rather than the classic involuting hemangioma of infancy (4).Fortunately, KMP is rare, affecting <1% of all children with vascular tumours. The optimum treatment of KMP has not been established, and its management can be very difficult. It often involves a multimodal approach, with many disciplines involved. In this article, we review the experience of managing KMP in a single institution. AbstractObjective: Kasabach-Merritt phenomenon (KMP) can lead to life-threatening bleeding, and its optimum treatment has not been established. We review the experience of managing KMP in a single institution. Methods: A retrospective chart review on all children with KMP treated at the Hospital for Sick Children, Toronto, over an 18 yr period was carried out. Results: All 15 patients had profound thrombocytopenia and hypofibrinogenemia at presentation, half had bleeding symptoms, and three had cardiac failure. All patients received corticosteroids. Five responded to steroids alone, given for an average of 13 wk, increasing platelets to >20 · 10 9 ⁄ L at a mean of 6.2 d and fibrinogen >1 g ⁄ dL at 25.6 d. Ten patients received at least one other therapeutic modality in addition to steroids, including vincristine, interferon, anti-platelet agents and pentoxifylline. Five patients received vincristine, for a mean of 6 wk, with two patients responding. Eight patients received interferon, for a mean of 4 months, with two patients responding. Overall, the mean time to increasing platelets >20 · 10 9 ⁄ L was 56 d, to >150 · 10 9 ⁄ L was 88 d and fibrinogen >1 g ⁄ dL 49 d. Ten patients showed a partial response to embolisation, with a mean of 2.8 procedures performed. Thrombotic complications occurred in 7%. Twelve patients remain alive, with relapse in six patients, all treated successfully. One patient died, and two patients have been lost to follow-up. Conclusion: KMP is a rare condition, with significant morbidity and mortality. The therapeutic approach should include a multidisciplinary team and consensus on guidelines.
Paget-Schroetter syndrome or effort-related upper extremity deep vein thrombosis is a rare condition that usually afflicts young healthy individuals, most commonly males. The cause is multifactorial but almost always involves extrinsic compression of the subclavian vein at the thoracic inlet, causing venous stenosis from repetitive trauma. The diagnosis of this condition may be difficult, and its delay may contribute to potential complications including thrombosis progression, pulmonary embolism, thrombosis recurrence, and post-thrombotic syndrome. Similarly, the best therapeutic option has not been established and in the lack of evidence-based guidelines, treatment may be extremely challenging especially in children, in whom long-term complications can be particularly disabling.
Sulfhemoglobinemia is a rare disorder characterized by the presence of sulfhemoglobin in the blood. It is typically drug-induced and may cause hypoxia, end-organ damage, and death through oxygen deprivation. We present here a case of non-drug-induced sulfhemoglobinemia in a 7-day-old preterm infant complicated by hemolytic anemia. Microbiota compositional analysis of fecal samples to investigate the origin of hydrogen sulphide revealed the presence of Morganella morganii at a relative abundance of 38% of the total fecal microbiota at the time of diagnosis. M morganii was not detected in the fecal samples of 40 age-matched control preterm infants. M morganii is an opportunistic pathogen that can cause serious infection, particularly in immunocompromised hosts such as neonates. Strains of M morganii are capable of producing hydrogen sulphide, and virulence factors include the production of a diffusible a-hemolysin. The infant in this case survived intact through empirical oral and intravenous antibiotic therapy, probiotic administration, and red blood cell transfusions. This coincided with a reduction in the relative abundance of M morganii to 3%. Neonatologists should have a high index of suspicion for intestinal pathogens in cases of non-drug-induced sulfhemoglobinemia and consider empirical treatment of the intestinal microbiota in this potentially lethal condition.
Upper-extremity deep venous thrombosis (UEDVT) is an increasingly important clinical problem in children. These events are classified as primary or secondary, with the latter being the most common and usually associated with the presence of a central venous line. Among primary UEDVT, the so-called Paget-Schroetter syndrome, effort-related or exercise-induced upper-extremity thrombotic event represents an extremely rare finding that has never been described in a pediatric series. The objective of the second part of this two-part article is to report the first pediatric series in a group of adolescents with this condition from a single center, describing their clinical features, management, and outcome. A retrospective chart review of 6 patients seen between December 2003 and April 2005 was conducted, with a median follow-up of 9 months (range 2–17). Four females and two males, all Caucasian, were enrolled with a median age of 16 years (range 14–17). In all cases, strenuous exercise was present in the month preceding diagnosis and mild trauma was present in only one case (weight lifting). At presentation, all patients had objective swelling of the affected limb for a median of 4 days (range 2–14), and 4 patients had UEDVT of the dominant arm. Thrombophilia investigation revealed that 50% had a combined prothrombotic state at presentation, and all patients were/are being treated with anticoagulation for 6 months (low-molecular-weight heparin followed by warfarin). Continuation of the initial symptoms was present in all cases but one at the 3-month clinic follow-up (last case has yet to reach 3 months of follow-up), and residual moderate to severe postthrombotic syndrome was present in all 3 cases followed for more than 12 months. Of those 3 patients followed for more than 1 year, 2 patients recurred despite having complete resolution of the thrombus after 6 months of anticoagulation, and the third patient underwent surgery with clinical improvement. Adolescents with UEDVT treated only with anticoagulation seem to have a poor outcome.
This study was funded by university departmental funds. Disclosure of potential conflict of interest: A. Manoharan has received travel support from Chiesi. B. Lipworth has received research support and consultancy fees from Chiesi, Teva, and Meda; has received travel support from Chiesi; is on the Boehringer Ingelheim advisory board; has received consultancy fees from Boehringer Ingelheim; has received research support from Janssen, AstraZeneca, Roche, and Pearl; and has mutual fund investments containing most of the large international pharmaceutical companies. The rest of the authors declare that they have no relevant conflicts of interest.
SUMMARYA 15-year-old girl with a recent diagnosis of acute lymphoblastic leukaemia was admitted to hospital with pancytopaenia after having received high-dose intrathecal methotrexate 1 day prior. During the next week she had intermittent episodes of alternating hemiparesis associated with speech arrest lasting minutes to hours at a time. The episodes were not associated with altered level of consciousness or headache. MRI of the brain showed features consistent with methotrexate encephalopathy. This report discusses the typical clinical and radiological features of methotrexate neurotoxicity in addition to differential diagnoses and the proposed pathophysiological mechanisms. BACKGROUND
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