Long-term follow-up of subtotal splenectomy for hereditary spherocytosis: a single-center study

Clinical Exome Sequencing Reveals Novel Mutations in SPTB Gene Associated with Hereditary Spherocytosis in Patients with Suspected Congenital Hemolytic Anemia

Congenital hemolytic anemia (CHA) is defined as the premature destruction of red blood cells (RBC) due to congenital or acquired defects. The hereditary form of hemolytic anemia can be divided into hemoglobinopathies, membranopathies, and enzymopathies. Hereditary spherocytosis (HS) is the most common inherited RBC membranopathy leading to congenital hemolytic anemia. To date; five genes have been associated with HS coding for cytoskeleton and transmembrane proteins, those genes are SPTB, SLC4A1, EPB42, ANK1, and SPTA1. Due to genetic heterogeneity, clinical exome sequencing (CES) was performed on four unrelated Moroccan patients referred for CHA investigation. Sanger sequencing and qPCR were performed to confirm CES results and to study the de novo character of identified variants. The molecular analysis revealed 3 novel mutations and one previously reported pathogenic variant of the SPTB gene confirming the diagnosis of HS in the four patients. Hereditary spherocytosis anemia is a genetically heterogenous disease which could be misdiagnosed clinically. The introduction of novel sequencing technologies can facilitate accurate genetic diagnosis, allowing an adapted care of the patient and his family.

[Surgery for primary splenic tumors and metastases of the spleen]

The correct indications for surgical treatment of primary splenic tumors as well as metastases of the spleen are challenging due to the rarity of the various entities. Primary solid splenic tumors include benign lesions, such as hemangiomas, hamartomas and sclerosing angiomatous nodular transformation (SANT) of the spleen. In these cases, surgical treatment is indicated only in the case of inconclusive imaging and after careful consideration of the risk-benefit ratio, even in the case of pronounced symptoms. In contrast, primary angiosarcoma or undifferentiated pleomorphic sarcoma as highly malignant tumors represent an urgent indication for surgery. Although more frequent than primary splenic malignancies, secondary splenic tumors are also not that frequent. Solitary splenic metastases are rare; however, from an oncological point of view they can be treated by resection. In the case of oligometastasis with splenic involvement, splenectomy is used only as part of a palliative concept in cases of pronounced symptoms or in the context of cytoreductive surgery. In general, the laparoscopic approach is to be preferred when the operation is technically feasible as it is associated with fewer pulmonary and infectious complications and a shorter hospital stay. In addition, to reduce the risk of severe infections after splenectomy, the option of partial splenectomy should be considered, especially for benign lesions. A thorough informing of the patient regarding both intraoperative and perioperative risks as well as potential long-term sequelae, especially severe infectious diseases, is an essential component of informed consent before surgery.

Long-term haematological response and maintained immunological function after laparoscopic subtotal splenectomy in patients with hereditary spherocytosis

INTRODUCTION

Subtotal or total splenectomy are recommended in severe and should be considered in intermediate forms of hereditary spherocytosis (HS). Data on laparoscopic subtotal splenectomy (LSTS) in HS patients are sparse.

METHODS

Thirty three patients with HS (median age 10.7 years (yrs), range 1.8-15.5) underwent LSTS. Baseline and follow-up investigation included haematological parameters, microscopic analysis of pitted erythrocytes (pitE), and B-cell subpopulations assessed by flow cytometry. Results were compared to those of non-splenectomised HS patients, HS patients after total splenectomy (TS), and healthy individuals.

RESULTS

After LSTS, haemoglobin levels were normalised in all patients. During median long-term follow-up of 3.9 yrs (range 1.1-14.9), only four patients presented mild anaemia. Despite re-growing of the remnant spleen none of the patients required a second surgical intervention. As compared to TS, PitE in LSTS patients were significantly lower and indicated normal to only moderately decreased spleen function. Relative but not absolute IgM memory B-cell counts were reduced in both LSTS and TS patients.

CONCLUSIONS

LSTS is effective for the treatment of patients with HS. A small remnant spleen is sufficient to provide adequate phagocytic function and to induce a pool of IgM memory B-cells.

Splenectomy improves erythrocyte functionality in spherocytosis based on septin abundance, but not maturation defects

Splenectomy improves the clinical parameters of patients with hereditary spherocytosis, but its potential benefit to red blood cell (RBC) functionality and the mechanism behind this benefit remain largely overlooked. Here, we compared 7 nonsplenectomized and 13 splenectomized patients with mutations in the β-spectrin or the ankyrin gene. We showed that hematological parameters, spherocyte abundance, osmotic fragility, intracellular calcium, and extracellular vesicle release were largely but not completely restored by splenectomy, whereas cryohemolysis was not. Affected RBCs exhibited decreases in β-spectrin and/or ankyrin contents and slight alterations in spectrin membrane distribution, depending on the mutation. These modifications were found in both splenectomized and nonsplenectomized patients and poorly correlated with RBC functionality alteration, suggesting additional impairments. Accordingly, we found an increased abundance of septins, small guanosine triphosphate-binding cytoskeletal proteins. Septins-2, -7, and -8 but not -11 were less abundant upon splenectomy and correlated with the disease severity. Septin-2 membrane association was confirmed by immunolabeling. Except for cryohemolysis, all parameters of RBC morphology and functionality correlated with septin abundance. The increased septin content might result from RBC maturation defects, as evidenced by (1) the decreased protein 4.2 and Rh-associated glycoprotein content in all patient RBCs, (2) increased endoplasmic reticulum remnants and endocytosis proteins in nonsplenectomized patients, and (3) increased lysosomal and mitochondrial remnants in splenectomized patients. Our study paves the way for a better understanding of the involvement of septins in RBC membrane biophysical properties. In addition, the lack of restoration of septin-independent cryohemolysis by splenectomy may call into question its recommendation in specific cases.

Clinical manifestations of adult hereditary spherocytosis with novel SPTB gene mutations and hyperjaundice: A case report

BACKGROUND

The aim of the present study was to enhance understanding of the diagnosis and treatment of atypical hereditary spherocytosis (HS), and to broaden the diagnostic thoughts of physicians for patients with jaundice.

CASE SUMMARY

A 28-year-old male presented with jaundice, bile duct stone, and splenomegaly, but without anemia. Other causes of jaundice were excluded, and gene sequencing revealed a novel heterozygous variant of c.1801C>T (p.Q601X) in exon 14 of the SPTB (NM_01355436) gene on chromosome 14 (chr14: 65260580) in the patient’s blood; the biological parents and child of the patient did not have similar variants. A splenectomy was performed on the patient and his bilirubin levels returned to normal after surgery. Thus, a novel gene variant causing HS was identified. This variant may result in the truncation of β-hemoglobin in the erythrocyte membrane, leading to loss of normal function, jaundice, and hemolytic anemia. The clinical manifestations of the patient were hyperjaundice and an absence of typical hemolysis during the course of the disease, which caused challenges for diagnosis by the clinicians.

CONCLUSION

Following a definitive diagnosis, genetic testing and response to treatment identified a gene variant site for a novel hemolytic anemia.

De novo variations of ANK1 gene caused hereditary spherocytosis in two Chinese children by affecting pre-mRNA splicing

BACKGROUND AND AIMS

Hereditary spherocytosis (HS) is one of the most common hereditary haemolytic disorders. Here, two unrelated families with the probands displaying typical manifestations of HS were enrolled. Our study aimed to characterize the effect of two novel variants in HS patients on gene splicing to help minimize the rate of misdiagnosis of HS and enhance clinicians' understanding of the disease.

PARTICIPANTS AND METHODS

A retrospective review was conducted. Peripheral blood samples were collected from all the family members, and genomic DNA was extracted for genetic diagnostics. First, high-throughput sequencing technology was used for the preliminary screening of candidate causative variants. Thereafter, the variants were verified via Sanger sequencing. Furthermore, a pathogenicity analysis of the detected variants was performed including in silico prediction and in vitro experiments. We constructed matched wild-type and mutant-type minigene plasmid of ANK1 based on HEK293T cells to address the effects of variants on mRNA splicing.

RESULTS

The c.1305 + 2 T > A (family1) and c.1305 + 2del (family2) variants were detected in the ANK1 gene. These two de novo mutations described by us which have not been reported prior to this study. Moreover, the validation results of splicing reporter systems revealed that the intronic mutations resulted in abnormal pre-mRNA splicing. Specifically, the minigene plasmid expressing the c.1305 + 2 T > A variant transcribed the two aberrant transcripts: r.1305_1306ins1305 + 1_1305 + 229 and r.1305_1306ins1305 + 1_1305 + 552. The minigene plasmid expressing c.1305 + 2del transcribed the two aberrant transcripts: r.1305_1306ins1305 + 1_1305 + 228 and r.1305_1306ins1305 + 1_1305 + 551.

CONCLUSION

The two de novo variants identified in the ANK1 gene were the genetic etiology of the probands with HS in our study. Our findings further enrich the HS genotype database and provide a basis for genetic counselling and molecular diagnosis.

[Congenital hemolytic anemias due to erythrocyte membrane and enzyme defects]

Erythrocyte membrane and enzyme defects are the most common cause of congenital hemolytic anemias in the Central European population. Diagnostics include erythrocyte morphology, special biochemical tests such as osmotic fragility (AGLT) and EMA. For enzymopenic hemolytic anemias, cost-effective biochemical analysis remains the gold standard, supplemented by molecular genetic diagnostics when appropriate. Therapeutically, near complete splenectomy reduces hemolysis significantly for spherocytosis. The residual spleen at least provides a considerable phagocytic function and better response to immunisation and by inference possibly better protection against severe post-splenectomy infection. For pyruvate kinase deficiency, which is not so rare, a new molecular therapy (Mitapivat) is currently being introduced. In G6PD deficiency, there are very few drugs that cause hemolytic crisis. Sudden onset of hemoglobinuria is an early important hallmark of severe hemolytic crisis in G6PD deficiency and these patients should be hospitalized. Aplastic crises in the setting of parvovirus B19 infection occur in all congenital hemolytic anemias. Transfusion is not preventable in most cases. Iron-excreting treatment is required in the rare patients in need of chronic transfusion.

Consideration of Splenectomy in Unstable Hemoglobinopathy: A Case Report of Hb Hammersmith (HBB: c.128T>C)

A 5-year-old female has been diagnosed with Hb Hammersmith (HBB: c.128T>C) and has required three blood transfusions thus far, with hemoglobin (Hb) levels dropping as low as 5.4 g/dL. An elective splenectomy is now being considered in order to reduce hemolysis and the need for transfusions. Of 18 previously reported cases of Hb Hammersmith, eight patients have reportedly undergone splenectomy, with only four of those studies reporting clinical improvement. Therefore, the role of splenectomy in unstable hemoglobinopathies remains unclear, but seems to be a promising option in Hb Hammersmith.

Diagnosis and clinical management of red cell membrane disorders

Heterogeneous red blood cell (RBC) membrane disorders and hydration defects often present with the common clinical findings of hemolytic anemia, but they may require substantially different management, based on their pathophysiology. An accurate and timely diagnosis is essential to avoid inappropriate interventions and prevent complications. Advances in genetic testing availability within the last decade, combined with extensive foundational knowledge on RBC membrane structure and function, now facilitate the correct diagnosis in patients with a variety of hereditary hemolytic anemias (HHAs). Studies in patient cohorts with well-defined genetic diagnoses have revealed complications such as iron overload in hereditary xerocytosis, which is amenable to monitoring, prevention, and treatment, and demonstrated that splenectomy is not always an effective or safe treatment for any patient with HHA. However, a multitude of variants of unknown clinical significance have been discovered by genetic evaluation, requiring interpretation by thorough phenotypic assessment in clinical and/or research laboratories. Here we discuss genotype-phenotype correlations and corresponding clinical management in patients with RBC membranopathies and propose an algorithm for the laboratory workup of patients presenting with symptoms and signs of hemolytic anemia, with a clinical case that exemplifies such a workup.

Partial splenectomy in children: Long-term reoperative outcomes☆

PURPOSE

Partial, or subtotal, splenectomy (PS) has become an accepted alternative to total splenectomy (TS) for management of hematologic disorders in children, but little is known about its long-term outcomes. Here, we present our institutional experience with partial splenectomy, to determine rate of subsequent TS or cholecystectomy and identify if any factors affected this need.

METHODS

All patients who underwent partial splenectomy at a single tertiary children's hospital were retrospectively reviewed from 2002 through 2019 after IRB approval. Primary outcome of interest was rate of reoperation to completion splenectomy (CS) and rate of cholecystectomy. Secondary outcome were positive predictor(s) for these subsequent procedures.

RESULTS

Twenty-four patients underwent PS, at median age 6.0 years, with preoperative spleen size of 12.7 cm by ultrasound. At median follow up time of 8.0 years, 29% of all patients and 24% of hereditary spherocytosis (HS) patients underwent completion splenectomy at median 34 months and 45 months, respectively. Amongst HS patients who did not have a cholecystectomy with or prior to PS, 39% underwent a delayed cholecystectomy following PS. There were no significant differences in age at index procedure, preoperative splenic volume, weight of splenic specimen removed, transfusion requirements, preoperative or postoperative hematologic parameters (including hemoglobin, hematocrit, total bilirubin, and reticulocyte count) amongst patients of all diagnoses and HS only who underwent PS alone compared to those who went on to CS. There were no cases of OPSS or deaths.

CONCLUSION

Partial splenectomy is a safe alternative to total splenectomy in children with hematologic disease with theoretical decreased susceptibility to OPSS. However, families should be counseled of a 29% chance of reoperation to completion splenectomy, and, in HS patients, a 39% chance of delayed cholecystectomy if not performed prior to or with PS. Further studies are needed to understand predictors of these outcomes.

Red cell membrane disorders: structure meets function

The mature red blood cell (RBC) lacks a nucleus and organelles characteristic of most cells, but it is elegantly structured to perform the essential function of delivering oxygen and removing carbon dioxide from all other cells while enduring the shear stress imposed by navigating small vessels and sinusoids. Over the past several decades, the efforts of biochemists, cell and molecular biologists, and hematologists have provided an appreciation of the complexity of RBC membrane structure, while studies of the RBC membrane disorders have offered valuable insights into structure-function relationships. Within the last decade, advances in genetic testing and its increased availability have made it possible to substantially build upon this foundational knowledge. Although disorders of the RBC membrane due to altered structural organization or altered transport function are heterogeneous, they often present with common clinical findings of hemolytic anemia. However, they may require substantially different management depending on the underlying pathophysiology. Accurate diagnosis is essential to avoid emergence of complications or inappropriate interventions. We propose an algorithm for laboratory evaluation of patients presenting with symptoms and signs of hemolytic anemia with a focus on RBC membrane disorders. Here, we review the genotypic and phenotypic variability of the RBC membrane disorders in order to raise the index of suspicion and highlight the need for correct and timely diagnosis.

Long‐term hematologic and clinical outcomes of splenectomy in children with hereditary spherocytosis and sickle cell disease

Background

Total splenectomy (TS) and partial splenectomy (PS) are used for children with congenital hemolytic anemia (CHA), although the long-term outcomes of these procedures are poorly defined. This report describes long-term outcomes of children with CHA requiring TS or PS.

Procedure

We collected data from children ages 2-17 with hereditary spherocytosis (HS) or sickle cell disease (SCD) requiring TS or PS from 1996 to 2016 from 14 sites in the Splenectomy in Congenital Hemolytic Anemia (SICHA) consortium using a prospective, observational patient registry. We summarized hematologic outcomes, clinical outcomes, and adverse events to 5 years after surgery. Hematologic outcomes were compared using mixed effects modeling.

Results

Over the study period, 110 children with HS and 97 children with SCD underwent TS or PS. From preoperatively compared to postoperatively, children with HS increased their mean hemoglobin level by 3.4 g/dL, decreased their mean reticulocyte percentage by 6.7%, and decreased their mean bilirubin by 2.4mg/dL. Hematologic improvements and improved clinical outcomes were sustained over 5 years of follow-up. For children with SCD, there was no change in hemoglobin after PS or TS following surgery, although all clinical outcomes were improved. Over 5 years, there was one child with HS and 5 children with SCD who developed post-splenectomy sepsis.

Conclusions

For children with HS, there are excellent long-term hematologic and clinical outcomes following either PS or TS. Although hemoglobin levels do not change after TS or PS in SCD, the long-term clinical outcomes for children with SCD are favorable.

Single-cell O2 exchange imaging shows that cytoplasmic diffusion is a dominant barrier to efficient gas transport in red blood cells

Blood is routinely tested for gas-carrying capacity (total hemoglobin), but this cannot determine the speed at which red blood cells (RBCs) exchange gases. Such information is critical for evaluating the physiological fitness of RBCs, which have very limited capillary transit times (<1 s) for turning over substantial volumes of gas. We developed a method to quantify gas exchange in individual RBCs and used it to show that restricted diffusion, imposed by hemoglobin crowding, is a major barrier to gas flows. Consequently, hematological disorders manifesting a change in cell shape or hemoglobin concentration have uncharted implications on gas exchange, which we illustrate using inherited anemias. With its single-cell resolution, the method can identify physiologically inferior subpopulations, providing a clinically useful appraisal of blood quality.

Disorders of oxygen transport are commonly attributed to inadequate carrying capacity (anemia) but may also relate to inefficient gas exchange by red blood cells (RBCs), a process that is poorly characterized yet assumed to be rapid. Without direct measurements of gas exchange at the single-cell level, the barriers to O₂ transport and their relationship with hematological disorders remain ill defined. We developed a method to track the flow of O₂ in individual RBCs by combining ultrarapid solution switching (to manipulate gas tension) with single-cell O₂ saturation fluorescence microscopy. O₂ unloading from RBCs was considerably slower than previously estimated in acellular hemoglobin solutions, indicating the presence of diffusional barriers in intact cells. Rate-limiting diffusion across cytoplasm was demonstrated by osmotically induced changes to hemoglobin concentration (i.e., diffusive tortuosity) and cell size (i.e., diffusion pathlength) and by comparing wild-type cells with hemoglobin H (HbH) thalassemia (shorter pathlength and reduced tortuosity) and hereditary spherocytosis (HS; expanded pathlength). Analysis of the distribution of O₂ unloading rates in HS RBCs identified a subpopulation of spherocytes with greatly impaired gas exchange. Tortuosity imposed by hemoglobin was verified by demonstrating restricted diffusivity of CO₂, an acidic gas, from the dissipative spread of photolytically uncaged H⁺ ions across cytoplasm. Our findings indicate that cytoplasmic diffusion, determined by pathlength and tortuosity, is a major barrier to efficient gas handling by RBCs. Consequently, changes in RBC shape and hemoglobin concentration, which are common manifestations of hematological disorders, can have hitherto unrecognized and clinically significant implications on gas exchange.

Laparoscopic ligation of splenic vessels for the treatment of hereditary spherocytosis in children

BACKGROUND

Total splenectomy is the most effective surgical treatment for hereditary spherocytosis (HS). Nevertheless, post-splenectomy sepsis and hypoimmunity can pose a great risk to children. Some alternative treatments have been proposed to avoid the post-splenectomy complications. In this study, we propose such a procedure (laparoscopic ligation of splenic vessels, L-LSV) for the treatment of HS in children and investigate its effectiveness and feasibility.

MATERIALS AND METHODS

A total of 17 children with HS who underwent the L-LSV at our hospital between May 2015 and Apr 2018 were enrolled in the current study. All patients were followed-up for 3-38 months (mean 19.8 months). The volume of spleen was preoperatively and postoperatively measured using the AW VolumeShare5. The size of functional spleen and the condition of splenic infarction were evaluated using ultrasound and computed tomography (CT) after surgery. The routine blood, biochemistry and coagulation tests were carried out after surgery.

RESULTS

The L-LSV was successfully performed in all patients. The average operative time was 115 min (range 60-180 min). No patients underwent blood transfusion during surgery, and the length of hospital stay varied 5-9 days after surgery (mean 7 days). Postoperatively, the red blood cells, platelet and hemoglobin were significantly increased (P < 0.05). The postoperative volume of functional spleen was significantly smaller than preoperative volume of spleen (307.393 ± 177.634 cm³ vs. 581.242 ± 270.260 cm³, P = 0.000). The recent volume of functional spleen was significantly bigger than the postoperative 1 month volume of functional spleen in ten children who were followed-up for more than 1 year (P = 0.004). The index of splenic infarction (the proportion of the postoperative 1-month volume of splenic infarction in the preoperative volume of spleen) was 0.31-0.99 (mean 0.53). There were no patients undergoing the blood transfusion after surgery.

CONCLUSIONS

The L-LSV is an effective treatment for HS in children; however, future studies should re-evaluate the long-term prognosis.

Clinical and laboratory outcomes following total or partial splenectomy in patients with hereditary spherocytosis

This study compared outcomes following total (TS) or partial splenectomy (PS) among patients with hereditary spherocytosis. Seventy-nine patients (TS = 33, PS = 46) were identified. The follow-up period was longer after PS (59.6 vs. 24.9 months, p < .001). Long-term adverse events occurred more frequently following PS (50% vs. 29%, p = .001). Anemia, jaundice, and fatigue recurred in six patients with PS, leading to five completion splenectomies. Hemoglobin was not different between PS and TS by 5 years post-procedure (12.3 vs. 13.4 g/dL, p = .25). Both PS and TS ameliorate symptoms and improve hematologic parameters. The rate of secondary surgery following PS should be considered when planning the initial surgical procedure.

Partial splenectomy: Who, when and how. A systematic review of the 2130 published cases

BACKGROUND/PURPOSE

In order to avoid consequences of total splenectomy (including severe postsplenectomy sepsis), partial splenectomy (PS) is increasingly reported. Without guidelines and indications concerning a rarely-indicated procedure, a review of literature should be an asset.

METHODS

A systematic review of all PSs from 1960 to December 2017 was performed, with special focus on surgical indications, sites of resection, approaches and techniques of vascular dissection and parenchymal section/hemostasis of the spleen, perioperative morbidity/mortality, including complications compelling to perform total splenectomy.

RESULTS

Among 2130 PSs, indications for resection were hematological disease in 1013 cases and nonhematological conditions in 1078, including various tumors in 142 and trauma in 184. Parenchymal transection was performed using several techniques through the years, most frequently after having induced partial ischemia by splenic hilum vascular dissection/ligation. 371 laparoscopic/robotic PSs were reported. Rescue total splenectomy was required in 75 patients.

CONCLUSIONS

Although good results are probably overestimated by such a retrospective review, PS should be considered as a procedure associated with a low morbidity/mortality. Nevertheless, severe complications are also reported, and the need of total splenectomy should not to be minimized. Laparoscopic/robotic procedures are increasingly performed, with good results and rare conversions.

TYPE OF STUDY

Systematic review.

LEVEL OF EVIDENCE

IV.

Inherited hemolytic anemia: a possessive beginner's guide

Significant advances have been made in diagnosis and clinical management of inherited red cell membrane disorders that result in hemolytic anemia. Membrane structural defects lead to hereditary spherocytosis (HS) and hereditary elliptocytosis (HE), whereas altered membrane transport function accounts for hereditary xerocytosis (HX) and hereditary overhydrated stomatocytosis (OHS). The degrees of membrane loss and resultant increases in cell sphericity determine the severity of anemia in HS and HE, and splenectomy leads to amelioration of anemia by increasing the circulatory red cell life span. Alterations in cell volume as a result of disordered membrane cation permeability account for reduced life span red cells in HX and OHS. Importantly, splenectomy is not beneficial in these 2 membrane transport disorders and is not recommended because it is ineffective and may lead to an increased risk of life-threatening thrombosis. Rational approaches are now available for the diagnosis and management of these inherited red cell disorders, and these will be discussed in this review.

A long-term follow-up study of subtotal splenectomy in children with hereditary spherocytosis

BACKGROUND

Hereditary spherocytosis (HS) is a heterogeneous hemolytic anemia treated with splenectomy in patients suffering from severe or moderate disease. Total splenectomy, however, renders patients vulnerable to overwhelming postsplenectomy infection despite preventive measures. Although subtotal splenectomy has been advocated as an alternative to total splenectomy, long-term follow-up data are scarce. We investigated how often hematologic recurrences requiring secondary total splenectomy occurred.

PROCEDURE

With a follow-up of at least 5 years, we analyzed the data of 12 patients, aged 11 years maximum (median 6.5 years), who had undergone intended subtotal splenectomy, and 9 patients (median age 11.9 years), who had undergone total splenectomy. We compared their hematologic results and searched for factors associated with secondary spleen surgery.

RESULTS

Hemolysis was reduced after subtotal splenectomy and absent after total splenectomy. Subtotal splenectomy was not successful in three children because no functional splenic remnant remained after 6 months (one conversion at surgery; one necrosis of splenic remnant; one early secondary splenectomy). Four children required secondary splenectomy after a median of 5 years for hematologic recurrence. In the remaining five patients, a functional splenic remnant was present for at least 5.5 years. The median time to secondary total splenectomy after intended subtotal splenectomy was 5.2 years. In all patients requiring secondary total splenectomy, increased reticulocyte levels within 2 years indicated hematologic recurrence.

CONCLUSIONS

Subtotal splenectomy can be an alternative for total splenectomy in young patients with HS. It allows for hematologic improvement and may preserve splenic immune function for as many as 5 years.

Indications and outcome of splenectomy in hematologic disease

Splenectomy is part of the therapeutic arsenal for benign or malignant hematological disorders that constitute the main indication for elective splenectomy. With the development of minimally invasive approaches, and in particular, laparoscopy, as well as the advent of monoclonal antibody therapy, the indications and the outcomes of splenectomy for hematologic disease have changed in recent years. Nonetheless, splenectomy has its place in hemoglobinopathies and hemolytic diseases, improves thrombocytopenia in refractory immune thrombocytopenic purpura, can reverse sequelae linked to voluminous splenomegaly secondary to myelofibrosis, or can be used for diagnostic purposes or for splenomegaly in lymphoproliferative syndromes.

Recommendations regarding splenectomy in hereditary hemolytic anemias

Hereditary hemolytic anemias are a group of disorders with a variety of causes, including red cell membrane defects, red blood cell enzyme disorders, congenital dyserythropoietic anemias, thalassemia syndromes and hemoglobinopathies. As damaged red blood cells passing through the red pulp of the spleen are removed by splenic macrophages, splenectomy is one possible therapeutic approach to the management of severely affected patients. However, except for hereditary spherocytosis for which the effectiveness of splenectomy has been well documented, the efficacy of splenectomy in other anemias within this group has yet to be determined and there are concerns regarding short- and long-term infectious and thrombotic complications. In light of the priorities identified by the European Hematology Association Roadmap we generated specific recommendations for each disorder, except thalassemia syndromes for which there are other, recent guidelines. Our recommendations are intended to enable clinicians to achieve better informed decisions on disease management by splenectomy, on the type of splenectomy and the possible consequences. As no randomized clinical trials, case control or cohort studies regarding splenectomy in these disorders were found in the literature, recommendations for each disease were based on expert opinion and were subsequently critically revised and modified by the Splenectomy in Rare Anemias Study Group, which includes hematologists caring for both adults and children.

New insights on hereditary erythrocyte membrane defects

After the first proposed model of the red blood cell membrane skeleton 36 years ago, several additional proteins have been discovered during the intervening years, and their relationship with the pathogenesis of the related disorders have been somewhat defined. The knowledge of erythrocyte membrane structure is important because it represents the model for spectrin-based membrane skeletons in all cells and because defects in its structure underlie multiple hemolytic anemias. This review summarizes the main features of erythrocyte membrane disorders, dividing them into structural and altered permeability defects, focusing particularly on the most recent advances. New proteins involved in alterations of the red blood cell membrane permeability were recently described. The mechanoreceptor PIEZO1 is the largest ion channel identified to date, the fundamental regulator of erythrocyte volume homeostasis. Missense, gain-of-function mutations in the PIEZO1 gene have been identified in several families as causative of dehydrated hereditary stomatocytosis or xerocytosis. Similarly, the KCNN4 gene, codifying the so called Gardos channel, has been recently identified as a second causative gene of hereditary xerocytosis. Finally, ABCB6 missense mutations were identified in different pedigrees of familial pseudohyperkalemia. New genomic technologies have improved the quality and reduced the time of diagnosis of these diseases. Moreover, they are essential for the identification of the new causative genes. However, many questions remain to solve, and are currently objects of intensive studies.