Vincristine-induced neuropathy in pediatric patients with acute lymphoblastic leukemia in Oman: Frequent autonomic and more severe cranial nerve involvement.

BACKGROUND: Vincristine (VCR) induced peripheral neuropathy is a common complication in children with acute lymphoblastic leukemia (ALL). PROCEDURES: A retrospective data analysis over an interval of 10 years (2006-2016) of all children with ALL seen at Sultan Qaboos University Hospital was carried out. Electronic medical records of eligible patients were reviewed. Patients with clinical evidence of neuropathy and abnormal nerve conduction studies (NCSs) were included in the study. RESULTS: Nineteen (nine females and 10 males) out of 103 pediatric patients developed VCR-related neuropathy, and their age ranged between 2.5 and 14 years. Symptoms started after 2-11 doses of VCR. All 19 patients had documented peripheral neuropathy on NCSs. The autonomic nervous system and cranial nerves affection was relatively common in our patients; two presented with bradycardia, two patients with unexplained tachycardia, and five had abdominal pain and constipation, complicated by typhlitis in two patients. One patient developed unilateral hearing loss. Two patients developed severe life-threatening cranial nerve involvement with bilateral ptosis and recurrent laryngeal nerve involvement presented as vocal cord paralysis, hoarseness of voice, frequent chocking, and aspiration episodes. CONCLUSIONS: Peripheral neuropathy was the commonest form of VCR-related neuropathy. Autonomic neuropathy was relatively common in our patients. Cranial neuropathy is a serious side effect of VCR that can be severe, involving multiple cranial nerves and needs prompt recognition and management. Concomitant administration of pyridoxine and pyridostigmine does not seem to protect against further neurological damage in some patients.

Efficacy and Safety of Dapsone Versus Trimethoprim/Sulfamethoxazol for Pneumocystis Jiroveci Prophylaxis in Children With Acute Lymphoblastic Leukemia With a Background of Ethnic Neutropenia.

STUDY OBJECTIVE: To study dapsone in comparison with trimethoprim/sulfamethoxazole (TMP/SMX) for Pneumocystis jiroveci (PJP) prophylaxis in children with acute lymphoblastic leukemia (ALL). DESIGN: A retrospective study with a prospective follow-up. PATIENTS: Pediatric ALL patients diagnosed between May 2009 and May 2014, who are still receiving or have completed their maintenance chemotherapy. Patients who completed chemotherapy were prospectively followed up for neutropenia. METHODS: TMP/SMX was used as the initial PJP prophylaxis. An alternative drug was indicated if the patient remained cytopenic for >3 weeks. Average absolute neutrophilic count (ANC), average % of oral mercaptopurine (6-MP), and methotrexate doses were calculated over a period of 6 months before and after shifting to dapsone. RESULTS: Sixty-two ALL patients were eligible for analysis. Twenty-four patients (38.7%) received TMP/SMX for PJP prophylaxis, whereas 34 patients received Dapsone (54.8%). Only 3 patients received IV pentamidine (4.8%), whereas 1 patient (1.6%) received atovaquone. The incidence of prophylaxis failure was 1/1041 months on TMP/SMX and 1/528 months on dapsone. After shifting to dapsone, patients maintained significantly higher ANC (1.46±0.46 vs. 1.17±0.40, P=0.0053), and received significantly higher doses of 6-MP (62.61%±11.45 vs. 57.45±10.14, P=0.0081) and methotrexate (64.9%±14.29 vs. 56.5%±9.9, P=0.0176), with a significantly shorter duration of chemotherapy interruption (1.94±1.2 vs. 3.25±1.29 wk, P=0.0002). CONCLUSIONS: Dapsone for PJP prophylaxis in ALL allowed patients to maintain higher ANC and to receive higher doses of chemotherapy, while maintaining a low incidence of PJP breakthrough infection.

Thiamine responsive megaloblastic anemia: the puzzling phenotype.

BACKGROUND: Thiamine responsive megaloblastic anemia (TRMA) is characterized by a triad of megaloblastic anemia, non-type 1 diabetes mellitus and sensorineural deafness. Other clinical findings have been described in few cases. The SLC19A2 gene on chromosome 1q 23.3 is implicated in all cases with TRMA. Our aim is to discuss the clinical manifestations of all Omani children diagnosed with TRMA and determine genotype-phenotype relationship. PROCEDURE: Clinical and laboratory data of all patients diagnosed in Oman were retrospectively collected. Mutation analysis of affected families was conducted using two Microsatellite markers. Genotyping was performed with fluorescent-labeled PCR primers. To define the deletion breakpoint region, PCR reactions were carried out using different primer pairs located at the introns 3 and 3'-untranslated region with Expand Long Template PCR kit. RESULTS: A total of six children have been diagnosed with this syndrome. They were five females and one male. They all presented with sensorineural deafness at birth while the age of anemia presentation ranged between 6 weeks to 19 months. They all belong to same family with complex interfamilial marriages and presented with the typical triad. Of interest is the very rare presentation of one patient with Uhl cardiac anomaly (total absence of right ventricular myocardium with apposition of endocardium and pericardium) that has never been described before in patients with TRMA. All patients have a novel large deletion of 5,224 bp involving exons 4, 5, and 6 of SLC19A2. CONCLUSIONS: TRMA is a disease of expanding phenotypic spectrum with poor genotype-phenotype correlation.

Single dose darbepoetin alfa is useful in reducing red cell transfusions in leukemic children receiving chemotherapy.

The role of erythropoiesis-stimulating agents (ESAs) in the management of chemotherapy-induced anemia (CIA) is becoming increasingly recognized in the field of medical oncology, with paucity of data in pediatrics. We evaluated the efficacy and tolerability of a single-dose darbepoetin alfa, a long-acting ESA, given to 35 pediatric acute lymphoblastic leukemia (ALL) children during induction chemotherapy. Compared to a retrospective control group, the studied patients have required significantly less units of packed red blood cells (0.88 units/patient in the studied group versus 2.04 units in controls), with no major side effects. We recommend further prospective double-blinded studies with more tailored dosing regimens in pediatric ALL cases and solid tumors.

Homozygous mild beta-thalassaemia promoter transversion -71 C>T HBB:c.-121 C>T.

Beta-thalassaemia is one of the most common genetic disorders worldwide, which is caused by absent or decreased synthesis of beta-globin chain subunits. Beta-thalassaemias are diverse groups of disease with a wide spectrum of clinical phenotypes. The clinical phenotypes can include asymptomatic forms of beta-thalassaemia minor, intermediate and severe transfusion dependent beta-thalassaemia major. Clinical severity varies depending on the underlying ß globin gene mutation. There are a number of mild ß-thalassaemia gene defects that could be referred as a 'silent carrier'. Identifying the underlying molecular defect is essential to predict phenotype severity for optimal management, tailored treatment and improved quality of life.We report the first identification of a homozygous point mutation located within the promoter region of the ß-globin gene at position -71 (C>T). The patient was a female child, who was referred to our clinic after she was found to have hypochromic microcytic anaemia with low haemoglobin (Hb) (67 g/L) and an Hb A2 level at the upper limit of the normal value (3.7%). This observation is a new example of homozygous mild ß-thalassaemia with a borderline Hb A2 level, and illustrates a potential source of pitfall in the diagnosis of ß-thalassaemia disease.