Practical Application of Multivendor MRI-Based R2* Mapping for Liver Iron Quantification at 1.5 T and 3.0 T.

BACKGROUND: Recent multicenter, multivendor MRI-based R2* vs. liver iron concentration (LIC) calibrations (i.e., MCMV calibrations) may facilitate broad clinical dissemination of R2*-based LIC quantification. However, these calibrations are based on a centralized offline R2* reconstruction, and their applicability with vendor-provided R2* maps is unclear. PURPOSE: To determine R2* ranges of agreement between the centralized and three MRI vendors' R2* reconstructions. STUDY TYPE: Prospective. SUBJECTS: Two hundred and seven subjects (mean age 37.6 ± 19.6 years; 117 male) with known or suspected iron overload from four academic medical centers. FIELD STRENGTH/SEQUENCE: Standardized multiecho spoiled gradient echo sequence at 1.5 T and 3.0 T for R2* mapping and a multiple spin-echo sequence at 1.5 T for LIC quantification. MRI vendors: GE Healthcare, Philips Healthcare, and Siemens Healthineers. ASSESSMENT: R2* maps were generated using both the centralized and vendor reconstructions, and ranges of agreement were determined. R2*-LIC linear calibrations were determined for each site, field strength, and reconstruction and compared with the MCMV calibrations. STATISTICAL TESTS: Bland-Altman analysis to determine ranges of agreement. Linear regression, analysis of covariance F tests, and Tukey's multiple comparison testing to assess reproducibility of calibrations across sites and vendors. A P value <0.05 was considered significant. RESULTS: The upper limits of R2* ranges of agreement were approximately 500, 375, and 330 s-1 for GE, Philips, and Siemens reconstructions, respectively, at 1.5 T and approximately 700 and 800 s-1 for GE and Philips, respectively, at 3.0 T. Within the R2* ranges of agreement, vendor R2*-LIC calibrations demonstrated high reproducibility (no significant differences between slopes or intercepts; P ≥ 0.06) and agreed with the MCMV calibrations (overlapping 95% confidence intervals). DATA CONCLUSION: Based on the determined upper limits, R2* measurements obtained from vendor-provided R2* maps may be reliably and practically used to quantify LIC less than approximately 8-13 mg/g using the MCMV calibrations and similar acquisition parameters as this study. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 3.

Treatment practices and response in kaposiform hemangioendothelioma: A multicenter cohort study.

BACKGROUND AND OBJECTIVES: Kaposiform hemangioendothelioma (KHE) and tufted angioma (TA) are rare vascular tumors in children historically associated with significant morbidity and mortality. This study was conducted to determine first-line therapy in the absence of available prospective clinical trials. METHODS: Patients from 17 institutions diagnosed with KHE/TA between 2005 and 2020 with more than 6 months of follow-up were included. Response rates to sirolimus and vincristine were compared at 3 and 6 months. Durability of response and response to other treatment modalities were also evaluated. RESULTS: Of 159 unique KHE/TA subjects, Kasabach-Merritt phenomenon (KMP) was present in 64 (40.3%), and only two patients were deceased (1.3%). Over 60% (n = 96) demonstrated treatment response at 3 months, and more than 70% (n = 114) by 6 months (no significant difference across groups). The vincristine group had higher radiologic response at 3 months compared to sirolimus (72.7% vs. 20%, p = .03), but there were no differences between these groups at 6 months. There were no differences in rates of recurrent or progressive disease between vincristine and sirolimus. CONCLUSIONS: In this large, multicenter cohort of 159 patients with KHE/TA, rates of KMP were consistent with historical literature, but the mortality rate (1.3%) was much lower. Overall treatment response rates were high (>70%), and there was no significant difference in treatment response or durability of disease comparing sirolimus to vincristine. Our results support individualized treatment decision plans depending on clinical scenario and patient/physician preferences. Response criteria and response rates reported here will be useful for guiding future treatment protocols for vascular tumors.

Assessment of Hormonal Contraceptive Utilization and Associated Odds of Hypercoagulopathy in Patients with Venous Malformations Using a National Claims Database.

BACKGROUND: Vascular anomalies that exhibit a slow velocity of blood flow, specifically venous malformations (VM), are associated with hypercoagulability. There is limited literature on the utilization of hormonal contraceptives (HCs) and the development of clotting events in female individuals diagnosed with VM. OBJECTIVE: We aimed to characterize HC utilization and associated odds of hypercoagulopathy in patients with VM of child-bearing age. METHODS: Using a national administrative claims database, we identified female patients with VM aged 15-49 years and a control population, matched for age and length of insurance enrollment, from 2016 to 2021. Multivariable logistic regression was used to estimate the odds of hypercoagulation events associated with HC use. RESULTS: Two hundred and sixty-seven (47.2%) patients with VM and 1284 (45.4%) control patients utilized HCs during the study period. Oral contraceptives were the most common HC for patients with and without VM (73.8% and 76.9% of those taking HCs, respectively), and estrogen-containing combination HCs (70.4% in patients with VM and 75.9% in controls) were more prevalent than progestin-only HCs in both populations. Despite a heightened baseline odds of hypercoagulopathy in patients with VM relative to patients without VM (odds ratio = 12.54; 95% confidence interval 7.73-20.3), HC use was not associated with an increased odds of hypercoagulation in the VM subpopulation (odds ratio = 0.82; 95% confidence interval 0.46-1.46). In contrast, tobacco use (odds ratio = 2.12; 95% confidence interval 1.09-4.12) and a history of coagulopathy (odds ratio = 3.92; 95% confidence interval 1.48-10.36) were predictive of thromboembolic events in the VM cohort. CONCLUSIONS: These findings suggest that patients with VM may safely use HCs with careful consideration of other risk factors for thromboses.

Multicenter Reproducibility of Liver Iron Quantification with 1.5-T and 3.0-T MRI.

Background MRI is a standard of care tool to measure liver iron concentration (LIC). Compared with regulatory-approved R2 MRI, R2* MRI has superior speed and is available in most MRI scanners; however, the cross-vendor reproducibility of R2*-based LIC estimation remains unknown. Purpose To evaluate the reproducibility of LIC via single-breath-hold R2* MRI at both 1.5 T and 3.0 T with use of a multicenter, multivendor study. Materials and Methods Four academic medical centers using MRI scanners from three different vendors (three 1.5-T scanners, one 2.89-T scanner, and two 3.0-T scanners) participated in this prospective cross-sectional study. Participants with known or suspected liver iron overload were recruited to undergo multiecho gradient-echo MRI for R2* mapping at 1.5 T and 3.0 T (2.89 T or 3.0 T) on the same day. R2* maps were reconstructed from the multiecho images and analyzed at a single center. Reference LIC measurements were obtained with a commercial R2 MRI method performed using standardized 1.5-T spin-echo imaging. R2*-versus-LIC calibrations were generated across centers and field strengths using linear regression and compared using F tests. Receiver operating characteristic (ROC) curve analysis was used to determine the diagnostic performance of R2* MRI in the detection of clinically relevant LIC thresholds. Results A total of 207 participants (mean age, 38 years ± 20 [SD]; 117 male participants) were evaluated between March 2015 and September 2019. A linear relationship was confirmed between R2* and LIC. All calibrations within the same field strength were highly reproducible, showing no evidence of statistically significant center-specific differences (P > .43 across all comparisons). Calibrations for 1.5 T and 3.0 T were generated, as follows: for 1.5 T, LIC (in milligrams per gram [dry weight]) = -0.16 + 2.603 × 10-2 R2* (in seconds-1); for 2.89 T, LIC (in milligrams per gram) = -0.03 + 1.400 × 10-2 R2* (in seconds-1); for 3.0 T, LIC (in milligrams per gram) = -0.03 + 1.349 × 10-2 R2* (in seconds-1). Liver R2* had high diagnostic performance in the detection of clinically relevant LIC thresholds (area under the ROC curve, >0.98). Conclusion R2* MRI enabled accurate and reproducible quantification of liver iron overload over clinically relevant ranges of liver iron concentration (LIC). The data generated in this study provide the necessary calibrations for broad clinical dissemination of R2*-based LIC quantification. ClinicalTrials.gov registration no.: NCT02025543 © RSNA, 2022 Online supplemental material is available for this article.

How we approach localized vascular anomalies.

Vascular anomalies are a group of disorders divided into two distinct subtypes: vascular tumors and vascular malformations. Vascular tumors are proliferative in nature, while malformations are nonproliferative. Simple, localized vascular malformations refer to a group of malformations that are localized to a single area of involvement. These simple malformations include capillary, lymphatic, venous, and arteriovenous malformations. The pediatric hematologists and oncologists are becoming increasingly involved in the diagnosis and management of these disorders. This review presents four cases as a means to discuss the diagnosis, clinical and imaging features, and management strategies of simple, localized vascular malformations.

Central Nervous System Xanthoma Disseminatum: Response to 2CdA in an Adolescent.

Xanthoma disseminatum is a normolipemic non-Langerhans cell histiocytosis characterized by red-brown rubbery papules of the skin which coalesce into plaque-like lesions with symmetric involvement of face, flexor, and intertriginous areas. Less commonly, xanthoma disseminatum may affect mucosal linings, abdominal organs, and the central nervous system, leading to endocrinopathies. We report a 12-year-old adolescent with mucosal, central nervous system, and painful cutaneous lesions, further complicated by diabetes insipidus and amenorrhea. Treatment with 2-chlorodeoxyadenosine led to relief of pain and significant improvement of mucosal, central nervous system, and cutaneous lesions, with subsequent restoration of menstrual cycles.

Genomic analysis of bone marrow failure and myelodysplastic syndromes reveals phenotypic and diagnostic complexity.

Accurate and timely diagnosis of inherited bone marrow failure and inherited myelodysplastic syndromes is essential to guide clinical management. Distinguishing inherited from acquired bone marrow failure/myelodysplastic syndrome poses a significant clinical challenge. At present, diagnostic genetic testing for inherited bone marrow failure/myelodysplastic syndrome is performed gene-by-gene, guided by clinical and laboratory evaluation. We hypothesized that standard clinically-directed genetic testing misses patients with cryptic or atypical presentations of inherited bone marrow failure/myelodysplastic syndrome. In order to screen simultaneously for mutations of all classes in bone marrow failure/myelodysplastic syndrome genes, we developed and validated a panel of 85 genes for targeted capture and multiplexed massively parallel sequencing. In patients with clinical diagnoses of Fanconi anemia, genomic analysis resolved subtype assignment, including those of patients with inconclusive complementation test results. Eight out of 71 patients with idiopathic bone marrow failure or myelodysplastic syndrome were found to harbor damaging germline mutations in GATA2, RUNX1, DKC1, or LIG4. All 8 of these patients lacked classical clinical stigmata or laboratory findings of these syndromes and only 4 had a family history suggestive of inherited disease. These results reflect the extensive genetic heterogeneity and phenotypic complexity of bone marrow failure/myelodysplastic syndrome phenotypes. This study supports the integration of broad unbiased genetic screening into the diagnostic workup of children and young adults with bone marrow failure and myelodysplastic syndromes.

Malignant transformation of infantile hemangioma to angiosarcoma: response to chemotherapy with bevacizumab.

We describe a child initially diagnosed with multi-focal infantile hemangioma (cutaneous, hepatic, pulmonary), a benign vascular lesion, which underwent malignant transformation to angiosarcoma. The use of anti-angiogenic agents, such as bevacizumab, an anti-vascular endothelial growth factor (VEGF) antibody, has been reported in adults with angiosarcoma. Treatment with chemotherapy (gemcitabine and docetaxel) and bevacizumab resulted in disease response with progression free survival of 12 months. This report describes the response to chemotherapy and bevacizumab in a child with angiosarcoma and highlights the potential for malignant transformation of benign vascular lesions and the need for careful monitoring.

Oxandrolone for the treatment of bone marrow failure in Fanconi anemia.

BACKGROUND: A majority of Fanconi anemia (FA) patients will experience bone marrow failure (BMF) and androgen therapy (most often oxymetholone) may be utilized as a treatment to improve BMF-related cytopenias. However, oxymetholone is associated with toxicities making identification of other agents of interest. In this study we aimed to evaluate the toxicity profile and hematologic response in patients with FA who are treated with low-dose oxandrolone, a synthetic non-fluorinated anabolic steroid, similar to oxymetholone, with known dosing thresholds for virilization. PROCEDURE: A single arm, Phase I/II study was designed to treat patients on low-dose oxandrolone. If no toxicity or hematologic response was noted at 16 weeks, a single dose escalation was offered. Subjects were regularly assessed for toxicity, including determinations of virilization, behavioral changes, and liver and kidney function. At 32 weeks, those who demonstrated hematologic response were allowed to continue study treatment, and those without improvement were deemed non-responsive. RESULTS: Nine subjects completed the study and were followed for a median of 99 weeks (46-136 weeks). Three (33.3%) subjects developed mild sub-clinical virilization and continued treatment with a dose reduction. None (0%) had adverse behavioral changes. Two (22.2%) developed elevated liver function tests at 42 and 105 weeks. Seven (77.8%) subjects had a hematologic response. CONCLUSION: Oxandrolone appears to be well-tolerated, has limited toxicities at the administered doses in FA with patients, and may be an alternative androgen for the treatment of BMF in FA.

Diffuse infantile hepatic hemangiomas: a report of four cases successfully managed with medical therapy.

We report four cases of diffuse infantile hepatic hemangioma, a rare but potentially life-threatening subset of hepatic hemangiomas. All patients demonstrated distinctive dome-shaped red-purple cutaneous hemangiomas. Two patients responded to steroids and propranolol (one in combination with vincristine), and two responded to steroids and vincristine. After a systematic literature review, we identified 26 previously reported cases of diffuse infantile hepatic hemangioma. Diffuse infantile hepatic hemangioma had a mortality rate of 17% and a >70% incidence of hypothyroidism, often severe (n = 30). More than one-third of patients developed heart failure (high output in half the cases). Based on our experience, early aggressive medical management, as well as thyroid replacement when indicated, should be initiated early in the course of diffuse infantile hepatic hemangioma pending evaluation for liver transplant.

Adherence to study medication and visits: data from the BABY HUG trial.

BACKGROUND: Subject retention and adherence are essential to maintain the power and validity of the Pediatric Hydroxyurea Phase III Clinical Trial (BABY HUG). We designed a study to assess adherence with study medication administration and study visits and to evaluate socioeconomic factors (SES) that may influence these measurements of adherence. These data are important for assessing impact of adherence on BABY HUG trial outcome and defining impact of SES on adherence. METHODS: Each subject's median study medication (MedAd) and mean visit adherence (VAd) were evaluated. We examined associations of adherence with SES of participating families. RESULTS: MedAd data were available on 153 of the 191 subjects who started randomized study medication. MedAd was 101.7% of volume prescribed, with 88.9% of subjects taking at least 80% of doses. VAd data were available on 185 of the 191 subjects who started randomized study medication. VAd was 97.3%, with 82.2% of subjects having no missed visits. During dose titration, subjects had on average 12.9% higher medication adherence than subjects who were on a stable dose and had less frequent study visits. MedAd and VAd were not significantly associated with SES. CONCLUSION: Subjects in the BABY HUG trial have had excellent adherence. SES was not associated with adherence, suggesting that SES should not be used as a criterion for enrolment in clinical trials. Additional efforts are needed to maintain medication adherence, particularly when the interval between scheduled visits increases. (ClinicalTrials.gov number, NCT00006400).

Neonatal alloimmune thrombocytopenia and neutropenia associated with maternal human leukocyte antigen antibodies.

Neonatal thrombocytopenia or neutropenia may result from passive transfusion of maternally derived antibodies. Antibodies against platelet antigens are commonly associated with neonatal alloimmune thrombocytopenia (NAIT), and anti-neutrophil antibodies are frequently identified in alloimmune neonatal neutropenia (ANN). Combined alloimmune cytopenias in the newborn are rarely reported; even fewer reports document human leukocyte antigen (HLA) antibodies as a potential cause of neonatal thrombocytopenia or neutropenia. We describe neutropenia and thrombocytopenia in a newborn associated with markedly elevated maternal HLA antibodies in the absence of anti-neutrophil or anti-platelet antibodies to highlight consideration of HLA antibodies in the pathogenesis of ANN and NAIT.

Idiopathic neutropenia of childhood is associated with Fas/FasL expression.

Idiopathic neutropenia (IN) in children is characterized by decreased neutrophil counts (<1500/microl), can be acute or chronic (greater than 6 months duration). The pathophysiology is not well understood; therefore, potential mechanisms of pediatric IN were investigated. An increase in Fas transcripts in neutrophils of IN patients compared to age-matched healthy control (HC) neutrophils was observed (p<0.005). Increased expression of Fas protein was found in IN neutrophils, while Fas surface expression on other immune cells was similar. Plasma from acute IN patients had higher protein levels of soluble FasL than chronic IN patients. When HC neutrophils were incubated in plasma from IN patients, greater rates of apoptosis were observed. Biochemical studies suggest the apoptotic factor(s) in plasma is heat-sensitive, non-IgG, and 12-50 kD protein. Addition of anti-sFasL blocking antibodies to patient plasma caused a statistically significant decrease in neutrophil apoptosis. These studies show that the Fas/FasL pathway could be associated with neutrophil apoptosis in childhood IN.

Darbepoetin alfa and ferric gluconate ameliorate the anemia associated with recessive dystrophic epidermolysis bullosa.

Our objective was to describe the efficacy of darbepoetin alfa and ferric gluconate complex in the treatment of the anemia associated with recessive dystrophic epidermolysis bullosa. To accomplish this aim, we retrospectively reviewed a series of patients with this disease treated in a single institution with darbepoetin alfa and parenteral iron for anemia. Four patients with recessive dystrophic epidermolysis bullosa were treated for a mean length of treatment of 14.5 months (4-18 months). Three patients received parenteral iron in the form of ferric gluconate complex and one received iron dextran. The mean pretreatment hemoglobin was 6.8 g/dL (4.9-9.6 g/dL). All four had improvements in their hemoglobin levels and energy levels with a mean increase in hemoglobin level of 2.8 g/dL (p = 0.003). We found darbepoetin alfa and ferric gluconate complex to be effective in the treatment of anemia associated with recessive dystrophic epidermolysis bullosa and to have distinct advantages over previously described formulations, and we concluded that they should be considered in the supportive care of this disease. We recommend the development of a standardized protocol for the evaluation and management of recessive dystrophic epidermolysis bullosa-associated anemia.

Increased prevalence of iron-overload associated endocrinopathy in thalassaemia versus sickle-cell disease.

Iron-overload associated endocrinopathy is the most frequently reported complication of chronic transfusion therapy in patients with thalassaemia (Thal). This study compared iron-overloaded subjects with Thal (n = 142; 54%M; age 25.8 +/- 8.1 years) and transfused sickle-cell disease (Tx-SCD; n = 199; 43%M, 24.9 +/- 13.2 years) to non-transfused SCD subjects (non-Tx-SCD; n = 64, 50%M, 25.3 +/- 11.3 years), to explore whether the underlying haemoglobinopathy influences the development of endocrinopathy. Subjects were recruited from 31 centres in the USA, Canada and the UK. Subjects with Thal had more evidence of diabetes (13% vs. 2%, P < 0.001), hypogonadism (40% vs. 4%, P < 0.001), hypothyroidism (10% vs. 2%, P = <0.001) and growth failure (33% vs. 7%, P < 0.001), versus Tx-SCD. Fifty-six per cent of Thal had more than one endocrinopathy compared with only 13% of Tx-SCD (P < 0.001). In contrast, Tx-SCD was not different from non-Tx-SCD. Multivariate analysis indicated that endocrinopathy was more likely in Thal than SCD [Odds Ratio (OR) = 9.4, P < 0.001], with duration of chronic transfusion a significant predictor (OR = 1.4 per 10 years of transfusion, P = 0.04). Despite iron overload, endocrinopathy was not increased in Tx-SCD versus non-Tx-SCD, suggesting that the underlying disease may modulate iron-related endocrine injury. However, because transfusion duration remained a significant predictor of endocrinopathy, these data should be confirmed in SCD subjects that have been chronically transfused for longer periods of time.

Granulocyte-macrophage colony stimulating factor and immunosuppression in the treatment of pediatric acquired severe aplastic anemia.

BACKGROUND: Immunosuppressive therapy (IS) is effective in the treatment of patients with acquired severe aplastic anemia (SAA). An enhanced myeloid response and decreased infection risk may be possible with the addition of a hematopoietic cytokine. Published data on the combination of cytokines and IS in patients with SAA are limited. The addition of G-CSF to IS shortens the time to neutrophil count recovery, but may not improve overall survival. Because GM-CSF acts differently than G-CSF, its use in combination with IS may be different. PROCEDURE: A retrospective chart review was performed on patients diagnosed with SAA and treated with IS and GM-CSF at St. Jude Children's Research Hospital. Hematologic recovery, prognostic factors, and infection data were collected. RESULTS: Eighteen patients were included in this study. The median age at diagnosis was 7.2 years (range 1.8-17.0). Ten patients (56%) had a complete response, four (22%) a partial response, and four (22%) no response. Median time to erythrocyte and platelet transfusion independence were 90 (18,243) and 64 days (18-243), and to discontinuation of treatment 287 days (90-730). Median time to partial (ANC > 500) and full (ANC > 1,500) neutrophil recovery were 41 and 51 days, respectively. Seventeen documented discrete infections occurred in six patients over 36 patient years. CONCLUSIONS: GM-CSF, in addition to IS, may shorten time to neutrophil count recovery, may be beneficial in decreasing infection rates, and may improve platelet response in patients with SAA. However, consistent with studies utilizing G-CSF, GM-CSF probably does not affect overall response rate. To fully answer whether or not cytokine therapy is of added value to IS in pediatric patients, a multi-institutional randomized trial is needed.

Hematologic problems in immigrants from Southeast Asia.

An increasing number of Southeast Asian immigrants have come to North America. Physicians who care for this population should be aware of the high prevalence of hematologic disorders and develop an approach to their diagnosis and management. Malaria and the hematologic sequelae, glucose-6-phophate dehydrogenase deficiency, the thalassemia syndromes, Southeast Asian ovalocytosis, visceral leishmaniasis, HIV infection, and iron-deficiency anemia, all of which may pertain to these patients, are reviewed in this article.

Natural history of moderate aplastic anemia in children.

BACKGROUND: Moderate aplastic anemia (MAA) in children is a rare, idiopathic condition of bone marrow insufficiency that can resolve spontaneously, persist for months or years, or progress to severe aplastic anemia (SAA). We evaluated the rate of progression to SAA. METHODS: We reviewed the records of 136 children referred for evaluation of bone marrow failure from 1978 to 2002 at St. Jude Children's Research Hospital. MAA was defined by a hypocellular bone marrow (<50%) and 2 or 3 cytopenias (absolute neutrophil count <1,500/mm(3), absolute reticulocyte count <40,000/mm(3), platelet count <100,000/mm(3)) lasting at least 6 weeks. RESULTS: Twenty-four patients met the criteria for MAA. At a median follow-up of 66 months (range, 10-293), 16 patients (67%) progressed to SAA, 5 (21%) had persistent MAA, and 3 (12%) had complete resolution of MAA. No risk factors for progression could be identified. CONCLUSIONS: When childhood MAA is treated with supportive care alone, 2/3 of patients progress to SAA.

Resolution of chronic hepatic sequestration in a patient with homozygous sickle cell disease receiving hydroxyurea.

Hepatic sequestration is an uncommon complication in patients with homozygous sickle cell disease. Although transfusion therapy has been effective for the acute condition, no definitive treatment of chronic hepatic sequestration has been identified. We describe a 17-year-old male patient with hemoglobin SS and chronic hepatic sequestration who was treated with long-term (60 months) hydroxyurea. After 36 months of HU therapy, the patient had both an excellent hematologic response and a resolution of hepatic sequestration, as evidenced by disappearance of clinical hepatomegaly, normalization of liver volume on serial computed tomography scans, as well as decreased sinusoidal dilatation and congestion and red blood cell sickling on liver biopsy. The findings in this case suggest that hydroxyurea may benefit patients who have unusual complications of sickle cell disease, such as chronic erythrocyte sickling in the liver.

Pseudotumor cerebri in two adolescents with acquired aplastic anemia.

A 13-year-old boy and a 16-year-old girl both presented with headaches and nausea after they were diagnosed with severe acquired aplastic anemia. Both patients had symptoms and signs consistent with the clinical syndrome of pseudotumor cerebri including headaches, nausea, papilledema, and elevated intracranial pressure. Both patients were treated with therapeutic lumbar puncture and acetazolamide, which relieved their symptoms. Acetazolamide dosage was given while the patients underwent an immunosuppressive regimen. We hypothesize that the pseudotumor cerebri in these two pediatric patients was the result of an increased production of cerebrospinal fluid in response to anemia and that the removal of fluid and treatment with acetazolamide appear to be helpful in such cases.