Effectiveness and Safety of Clofarabine Monotherapy or Combination Treatment in Relapsed/Refractory Childhood Acute Lymphoblastic Leukemia: A Pragmatic, Non-interventional Study in Korea / Journal of the Korean Cancer Association, 대한암학회지

Purpose@#Effectiveness and safety of clofarabine (one of the treatment mainstays in pediatric patients with relapsed/refractory acute lymphoblastic leukemia [ALL]) was assessed in Korean pediatric patients with ALL to facilitate conditional coverage with evidence development. @*Materials and Methods@#In this multicenter, prospective, observational study, patients receiving clofarabine as mono/combination therapy were followed up every 4-6 weeks for 6 months or until hematopoietic stem cell transplantation (HSCT). Response rates, survival outcomes, and adverse events were assessed. @*Results@#Sixty patients (2-26 years old; 65% B-cell ALL, received prior ≥ 2 regimen, 68.3% refractory to previous regimen) were enrolled and treated with at least one dose of clofarabine; of whom 26 (43.3%) completed 6 months of follow-up after the last dose of clofarabine. Fifty-eight patients (96.7%) received clofarabine combination therapy. Overall remission rate (complete remission [CR] or CR without platelet recovery [CRp]) was 45.0% (27/60; 95% confidence interval [CI], 32.4 to 57.6) and the overall response rate (CR, CRp, or partial remission [PR]) was 46.7% (28/60; 95% CI, 34.0 to 59.3), with 11 (18.3%), 16 (26.7%), and one (1.7%) patients achieving CR, CRp, and PR, respectively. The median time to remission was 5.1 weeks (95% CI, 4.7 to 6.1). Median duration of remission was 16.6 weeks (range, 2.0 to 167.6 weeks). Sixteen patients (26.7%) proceeded to HSCT. There were 24 deaths; 14 due to treatment-emergent adverse events. @*Conclusion@#Remission with clofarabine was observed in approximately half of the study patients who had overall expected safety profile; however, there was no favorable long-term survival outcome in this study.

Clinical Features and Treatment Outcome of Soft Tissue Clear Cell Sarcoma / 임상소아혈액종양

BACKGROUND: Soft tissue clear cell sarcoma is a rare tumor which originates from neural crest cells. Due to its rarity and lack of established treatment, the prognosis of clear cell sarcoma is poor. Here, we reviewed the clinical data and outcome of patients diagnosed with soft tissue clear cell sarcoma in our institution.METHODS: A retrospective study was conducted on pediatric patients who were treated for pathologically confirmed soft tissue clear cell sarcoma at the Seoul National University Hospital, between January 2000 and July 2017.RESULTS: Six patients (3 boys and 3 girls) were diagnosed with soft tissue clear cell sarcoma at a median age of 14 years 4 months (range 11 years 7 months - 19 years 3 months). The median size of the tumor was 5.6 cm (range, 0.6 cm to 7.9 cm). The most frequent symptom was pain (67%), and the most common primary site was the lower limb (67%). Three patients (50%) presented with metastases at diagnosis. Four patients underwent chemotherapy with various therapeutic combinations. Four patients received surgical resection. Only one patient received local radiotherapy. One patient died of primary refractory disease, three patients relapsed, while the remaining two survive event-free.CONCLUSION: Soft tissue clear cell sarcoma is a rare and highly aggressive tumor, for which there is no established treatment. All surviving patients received surgery, indicating that surgery is a key treatment modality. Further genetic studies of soft tissue clear cell sarcoma are needed to find a better treatment strategy.

WHIM Syndrome With a Novel CXCR4 Variant in a Korean Child

No abstract available.

Clinical Features and Treatment Outcome of Soft Tissue Clear Cell Sarcoma / 임상소아혈액종양

BACKGROUND: Soft tissue clear cell sarcoma is a rare tumor which originates from neural crest cells. Due to its rarity and lack of established treatment, the prognosis of clear cell sarcoma is poor. Here, we reviewed the clinical data and outcome of patients diagnosed with soft tissue clear cell sarcoma in our institution. METHODS: A retrospective study was conducted on pediatric patients who were treated for pathologically confirmed soft tissue clear cell sarcoma at the Seoul National University Hospital, between January 2000 and July 2017. RESULTS: Six patients (3 boys and 3 girls) were diagnosed with soft tissue clear cell sarcoma at a median age of 14 years 4 months (range 11 years 7 months - 19 years 3 months). The median size of the tumor was 5.6 cm (range, 0.6 cm to 7.9 cm). The most frequent symptom was pain (67%), and the most common primary site was the lower limb (67%). Three patients (50%) presented with metastases at diagnosis. Four patients underwent chemotherapy with various therapeutic combinations. Four patients received surgical resection. Only one patient received local radiotherapy. One patient died of primary refractory disease, three patients relapsed, while the remaining two survive event-free. CONCLUSION: Soft tissue clear cell sarcoma is a rare and highly aggressive tumor, for which there is no established treatment. All surviving patients received surgery, indicating that surgery is a key treatment modality. Further genetic studies of soft tissue clear cell sarcoma are needed to find a better treatment strategy.

Targeted busulfan and fludarabine-based conditioning for bone marrow transplantation in chronic granulomatous disease / 소아과

Chronic granulomatous disease (CGD) is a primary immunodeficiency disease caused by impaired phagocytic function. Hematopoietic stem cell transplantation (HSCT) is a definitive cure for CGD; however, the use of HSCT is limited because of associated problems, including transplantation-related mortality and engraftment failure. We report a case of a patient with CGD who underwent successful HSCT following a targeted busulfan and fludarabine reduced-toxicity myeloablative conditioning. Intravenous busulfan was administered once daily for 4 consecutive days (days –8 to –5), and the target area under the curve was 75,000 µg·hr/L. Fludarabine (40 mg/m2) was administered once daily for 6 consecutive days from days –8 to –3. Antithymocyte globulin (2.5 mg/kg/day) was administered from days –4 to –2. The patient underwent successful engraftment and did not have any severe toxicity related to the transplantation. Conditioning with a targeted busulfan and fludarabine regimen could provide a better outcome for HSCT in CGD, with close regulation of the busulfan dose.

Clinical Characteristics and Treatment Outcome of the Desmoplastic Small Round Cell Tumor / 임상소아혈액종양

BACKGROUND: Desmoplastic small round cell tumor (DSRCT) is an aggressive malignancy with a poor prognosis. DSRCT is a rare disease, and therefore a standard treatment regimen has not been established. In this study, we reviewed the clinical characteristics and treatment outcomes of pediatric DSRCT patients.METHODS: We retrospectively reviewed the medical records of 5 DSRCT patients (2 boys, 3 girls) that were diagnosed and treated with DSRCT at Seoul National University Children's Hospital from January 1999 to January 2015.RESULTS: The median age at diagnosis was 11 years 5months (range 4 years 10 months-17 years 2 months). The most frequent symptoms were abdominal pain (60%). The primary sites were gastrointestinal tract, bladder, and omentum, and the involved sites were the liver, gastrointestinal tract, bladder and bone. Three patients had multiple metastases at diagnosis. Two patients underwent upfront surgical excision of primary tumor, and the remaining 3 patients received neo-adjuvant chemotherapy after the diagnosis was confirmed by using needle biopsy. Combination chemotherapy was administered to all patients in addition to radiotherapy (median dose 45 Gy, range 17.5-54 Gy). Four patients showed disease progression or relapse, resulting in a 20% overall survival rate. At the time of analysis, one patient is alive. She had localized disease at the time of diagnosis and were treated with upfront surgery, chemotherapy, and high-dose chemotherapy with autologous stem cell transplantation and radiotherapy.CONCLUSION: Patients with DSRCT have a poor prognosis, even after multimodal treatment. Further studies are needed to determine the prognostic factors of DSRCT.

A Case of Long-term Survival with Autologous Recovery after Double Cord Blood Transplantation for Juvenile Myelomonocytic Leukemia / 임상소아혈액종양

A 1.1 year old boy was admitted to the Seoul National University Children's Hospital because of incidental findings of hepatosplenomegaly, skin lesion and multiple intra- abdominal lymphadenopathies. Anemia and thrombocytopenia were found based on the initial complete blood count (CBC) measurements. Because of bicytopenia and hepatosplenomegaly, bone marrow examination was performed which revealed hypercellular marrow with increased monocytes and granulopoiesis. The hemoglobin F level was high for his age, and monocyte production was increased. The patient was diagnosed with juvenile myelomonocytic leukemia at the age of 1.2 years. Chemotherapy with cytarabine, etoposide, vincristine, and isotretinoin was initiated. After 6 cycles of chemotherapy, the CBC normalized. He underwent double cord blood transplantation (dCBT), but chimerism studies showed autologous recovery. However, he did not show relapse during the 5 years post-transplant during which he received isotretinoin. He is surviving disease-free 9 years after dCBT.

Clinical Characteristics and Treatment Outcome of the Desmoplastic Small Round Cell Tumor / 임상소아혈액종양

BACKGROUND: Desmoplastic small round cell tumor (DSRCT) is an aggressive malignancy with a poor prognosis. DSRCT is a rare disease, and therefore a standard treatment regimen has not been established. In this study, we reviewed the clinical characteristics and treatment outcomes of pediatric DSRCT patients. METHODS: We retrospectively reviewed the medical records of 5 DSRCT patients (2 boys, 3 girls) that were diagnosed and treated with DSRCT at Seoul National University Children's Hospital from January 1999 to January 2015. RESULTS: The median age at diagnosis was 11 years 5months (range 4 years 10 months-17 years 2 months). The most frequent symptoms were abdominal pain (60%). The primary sites were gastrointestinal tract, bladder, and omentum, and the involved sites were the liver, gastrointestinal tract, bladder and bone. Three patients had multiple metastases at diagnosis. Two patients underwent upfront surgical excision of primary tumor, and the remaining 3 patients received neo-adjuvant chemotherapy after the diagnosis was confirmed by using needle biopsy. Combination chemotherapy was administered to all patients in addition to radiotherapy (median dose 45 Gy, range 17.5-54 Gy). Four patients showed disease progression or relapse, resulting in a 20% overall survival rate. At the time of analysis, one patient is alive. She had localized disease at the time of diagnosis and were treated with upfront surgery, chemotherapy, and high-dose chemotherapy with autologous stem cell transplantation and radiotherapy. CONCLUSION: Patients with DSRCT have a poor prognosis, even after multimodal treatment. Further studies are needed to determine the prognostic factors of DSRCT.

A Case of Long-term Survival with Autologous Recovery after Double Cord Blood Transplantation for Juvenile Myelomonocytic Leukemia / 임상소아혈액종양

A 1.1 year old boy was admitted to the Seoul National University Children's Hospital because of incidental findings of hepatosplenomegaly, skin lesion and multiple intra- abdominal lymphadenopathies. Anemia and thrombocytopenia were found based on the initial complete blood count (CBC) measurements. Because of bicytopenia and hepatosplenomegaly, bone marrow examination was performed which revealed hypercellular marrow with increased monocytes and granulopoiesis. The hemoglobin F level was high for his age, and monocyte production was increased. The patient was diagnosed with juvenile myelomonocytic leukemia at the age of 1.2 years. Chemotherapy with cytarabine, etoposide, vincristine, and isotretinoin was initiated. After 6 cycles of chemotherapy, the CBC normalized. He underwent double cord blood transplantation (dCBT), but chimerism studies showed autologous recovery. However, he did not show relapse during the 5 years post-transplant during which he received isotretinoin. He is surviving disease-free 9 years after dCBT.

Extra-cranial Malignant Rhabdoid Tumor in Children: A Single Institute Experience / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Malignant rhabdoid tumor (MRT) is a rare and highly aggressive tumor that affects young children. Due to its extreme rarity, most of the available data are based on retrospective case series. To add to the current knowledge of this disease, we reviewed the patients treated for extra-cranial MRT in our institute. MATERIALS AND METHODS: A retrospective medical record review was conducted on children treated for pathologically confirmed extra-cranial MRT at Seoul National University Children's Hospital between January 2003 and May 2013. RESULTS: Eleven patients (7 boys, 4 girls) were diagnosed with extra-cranial MRT at a median age of 9 months old. INI1 staining was important in the pathological confirmation. Six patients (55%) had renal MRT and five (45%) had soft tissue MRT. Five patients (45%) had metastases at diagnosis. All patients underwent chemotherapy, eight patients (73%) underwent surgery, six patients (55%) received therapeutic radiotherapy, and four patients (36%) underwent high dose chemotherapy with autologous stem cell rescue (HDCT/ASCR) with melphalan, etoposide, and carboplatin. Five patients (45%) died of disease following progression (n=3) or relapse (n=2), however, there was no treatment related mortality. The overall survival of the cohort was 53.0% and the event-free survival was 54.5% with a median follow-up duration of 17.8 months (range, 2.3 to 112.3 months). CONCLUSION: Extra-cranial MRT is still a highly aggressive tumor in young children. However, the improved survival of our cohort is promising and HDCT/ASCR with melphalan, etoposide, and carboplatin may be a promising treatment option.

Hemophagocytic lymphohistiocytosis diagnosed by brain biopsy / 소아과

Hemophagocytic lymphohistiocytosis (HLH) is characterized by fever, splenomegaly, jaundice, and pathologic findings of hemophagocytosis in bone marrow or other tissues such as the lymph nodes and liver. Pleocytosis, or the presence of elevated protein levels in cerebrospinal fluid, could be helpful in diagnosing HLH. However, the pathologic diagnosis of the brain is not included in the diagnostic criteria for this condition. In the present report, we describe the case of a patient diagnosed with HLH, in whom the brain pathology, but not the bone marrow pathology, showed hemophagocytosis. As the diagnosis of HLH is difficult in many cases, a high level of suspicion is required. Moreover, the pathologic diagnosis of organs other than the bone marrow, liver, and lymph nodes may be a useful alternative.

Nasopharyngeal Carcinoma in Children and Adolescents: Single Institution Study / 임상소아혈액종양

BACKGROUND: Nasopharyngeal carcinoma (NPC) is very rare in children and adolescents. The aim of this study was to evaluate clinical characteristics and treatment outcomes of pediatric NPC.METHODS: Medical records of 9 patients treated for NPC at the Seoul National University Children's Hospital between 1988 and 2012 were analyzed retrospectively.RESULTS: The median age at diagnosis was 11 years (range, 9-13 years). One patient had stage II disease, 3 had stage III disease, and 5 had stage IV disease. The histologic subtypes were undifferentiated carcinoma and squamous cell carcinoma in 7 and 2 patients, respectively. All patients were initially treated with cisplatin (100 mg/m2 intravenous [IV] every 4 weeks for 4-6 months), bleomycin (15 unit/m2 IV every 1 weekx7), and fluorouracil (1,000 mg/m2 IV every 4 weeks for 1 year). Eight patients received radiotherapy with doses of 45-59.4 Gy at the primary site and neck nodes. Seven patients (77.8%) achieved complete remission, 1 (11.1%) achieved partial remission, and 1 (11.1%) showed disease progression. Six patients developed fluorouracil-related neurotoxicity; the regimen was changed to cisplatin, epirubicin, and bleomycin in five of the 6 patients. One patient died of progressive disease without responding to treatment. Treatment-related mortality occurred in 1 patient owing to septic shock. Secondary osteosarcoma developed in 1 patient 6 years after treatment. The overall survival was 77.8%, with a median follow-up of 40.8 months (range, 4.5-287.6 months).CONCLUSION: Children and adolescents with advanced NPC treated with combined chemotherapy and radiotherapy have a good survival rate.

A Case of Thrombotic Microangiopathy Following Autologous Stem Cell Transplantation / 임상소아혈액종양

Transplantation-associated thrombotic microangiopathy (TA-TMA) is an uncommon but devastating complication in patients who undergo hematopoietic stem cell transplantation (SCT). However, the optimal treatment strategy for TA-TMA is unclear. We report a rare case of TA-TMA in a 39-month-old boy who underwent tandem autologous SCT (autoSCT) for high-risk medulloblastoma. TA-TMA developed 64 days after the second autoSCT with microangiopathic hemolytic anemia, fever, renal impairment, acute respiratory distress syndrome and posterior reversible encephalopathy syndrome. The patient recovered after plasmapheresis and methylprednisolone therapy. He had mild to moderate deficiency of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS-13). The patient's clinical course would suggest that plasmapheresis and methylprednisolone therapy could be a treatment option for TA-TMA. Early intervention is needed to aid the recovery of the patient who is suspected for TA-TMA.

Advancements in the treatment of pediatric acute leukemia and brain tumor - continuous efforts for 100% cure / 소아과

Treatment outcomes of pediatric cancers have improved greatly with the development of improved treatment protocols, new drugs, and better supportive measures, resulting in overall survival rates greater than 70%. Survival rates are highest in acute lymphoblastic leukemia, reaching more than 90%, owing to risk-based treatment through multicenter clinical trials and protocols developed to prevent central nervous system relapse and testicular relapse in boys. New drugs including clofarabine and nelarabine are currently being evaluated in clinical trials, and other targeted agents are continuously being developed. Chimeric antigen receptor-modified T cells are now attracting interest for the treatment of recurrent or refractory disease. Stem cell transplantation is still the most effective treatment for pediatric acute myeloid leukemia (AML). However, in order to reduce treatment-related death after stem cell transplantation, there is need for improved treatments. New drugs and targeted agents are also needed for improved outcome of AML. Surgery and radiation therapy have been the mainstay for brain tumor treatment. However, chemotherapy is becoming more important for patients who are not eligible for radiotherapy owing to age. Stem cell transplant as a means of high dose chemotherapy and stem cell rescue is a new treatment modality and is often repeated for improved survival. Drugs such as temozolomide are new chemotherapeutic options. In order to achieve 100% cure in children with pediatric cancer, every possible treatment modality and effort should be considered.

Nasopharyngeal Carcinoma in Children and Adolescents: Single Institution Study / 임상소아혈액종양

BACKGROUND: Nasopharyngeal carcinoma (NPC) is very rare in children and adolescents. The aim of this study was to evaluate clinical characteristics and treatment outcomes of pediatric NPC. METHODS: Medical records of 9 patients treated for NPC at the Seoul National University Children's Hospital between 1988 and 2012 were analyzed retrospectively. RESULTS: The median age at diagnosis was 11 years (range, 9-13 years). One patient had stage II disease, 3 had stage III disease, and 5 had stage IV disease. The histologic subtypes were undifferentiated carcinoma and squamous cell carcinoma in 7 and 2 patients, respectively. All patients were initially treated with cisplatin (100 mg/m2 intravenous [IV] every 4 weeks for 4-6 months), bleomycin (15 unit/m2 IV every 1 weekx7), and fluorouracil (1,000 mg/m2 IV every 4 weeks for 1 year). Eight patients received radiotherapy with doses of 45-59.4 Gy at the primary site and neck nodes. Seven patients (77.8%) achieved complete remission, 1 (11.1%) achieved partial remission, and 1 (11.1%) showed disease progression. Six patients developed fluorouracil-related neurotoxicity; the regimen was changed to cisplatin, epirubicin, and bleomycin in five of the 6 patients. One patient died of progressive disease without responding to treatment. Treatment-related mortality occurred in 1 patient owing to septic shock. Secondary osteosarcoma developed in 1 patient 6 years after treatment. The overall survival was 77.8%, with a median follow-up of 40.8 months (range, 4.5-287.6 months). CONCLUSION: Children and adolescents with advanced NPC treated with combined chemotherapy and radiotherapy have a good survival rate.

A Case of Thrombotic Microangiopathy Following Autologous Stem Cell Transplantation / 임상소아혈액종양

Transplantation-associated thrombotic microangiopathy (TA-TMA) is an uncommon but devastating complication in patients who undergo hematopoietic stem cell transplantation (SCT). However, the optimal treatment strategy for TA-TMA is unclear. We report a rare case of TA-TMA in a 39-month-old boy who underwent tandem autologous SCT (autoSCT) for high-risk medulloblastoma. TA-TMA developed 64 days after the second autoSCT with microangiopathic hemolytic anemia, fever, renal impairment, acute respiratory distress syndrome and posterior reversible encephalopathy syndrome. The patient recovered after plasmapheresis and methylprednisolone therapy. He had mild to moderate deficiency of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS-13). The patient's clinical course would suggest that plasmapheresis and methylprednisolone therapy could be a treatment option for TA-TMA. Early intervention is needed to aid the recovery of the patient who is suspected for TA-TMA.

Pediatric Extranodal NK/T Cell Lymphoma in a Single Institution / 임상소아혈액종양

BACKGROUND: Extranodal NK/T cell lymphoma (ENKTL) is extremely rare in children, and there have been few reports on pediatric ENKTL. The purpose of this study was to investigate the clinical features and treatment outcomes of pediatric ENKTL. METHODS: The study involved a review of the medical records of eight pediatric patients who were diagnosed with ENKTL. RESULTS: Among the eight patients, three were in stage I of the disease, and five were in stages II to IV. The median follow-up period was 90.8 months. Two stage I patients were nasal type, and the other six patients were non-nasal type. Two patients died within one month of diagnosis; thus, five patients underwent chemotherapy including L-asparaginase, and one patient underwent chemotherapy without L-asparaginase. All patients showed an overall response after induction chemotherapy, with four showing a complete response (CR) and two showing a partial response (PR). Two newly diagnosed patients and one relapsed patient underwent autologous peripheral blood stem cell transplantation (aPBSCT). The five-year overall survival (OS) rate was 50%, and the five-year progression-free survival (PFS) rate was 46.9%. Ann Arbor stage was a significant prognostic factor for OS (P=0.042). CONCLUSION: Advanced-stage pediatric ENKTL was associated with a grave prognosis. However, intensive chemotherapy with L-asparaginase resulted in an overall response, and aPBSCT could be beneficial for pediatric ENKTL.

Pediatric Extranodal NK/T Cell Lymphoma in a Single Institution / 임상소아혈액종양

BACKGROUND: Extranodal NK/T cell lymphoma (ENKTL) is extremely rare in children, and there have been few reports on pediatric ENKTL. The purpose of this study was to investigate the clinical features and treatment outcomes of pediatric ENKTL. METHODS: The study involved a review of the medical records of eight pediatric patients who were diagnosed with ENKTL. RESULTS: Among the eight patients, three were in stage I of the disease, and five were in stages II to IV. The median follow-up period was 90.8 months. Two stage I patients were nasal type, and the other six patients were non-nasal type. Two patients died within one month of diagnosis; thus, five patients underwent chemotherapy including L-asparaginase, and one patient underwent chemotherapy without L-asparaginase. All patients showed an overall response after induction chemotherapy, with four showing a complete response (CR) and two showing a partial response (PR). Two newly diagnosed patients and one relapsed patient underwent autologous peripheral blood stem cell transplantation (aPBSCT). The five-year overall survival (OS) rate was 50%, and the five-year progression-free survival (PFS) rate was 46.9%. Ann Arbor stage was a significant prognostic factor for OS (P=0.042). CONCLUSION: Advanced-stage pediatric ENKTL was associated with a grave prognosis. However, intensive chemotherapy with L-asparaginase resulted in an overall response, and aPBSCT could be beneficial for pediatric ENKTL.

Pediatric Extranodal NK/T Cell Lymphoma in a Single Institution / 임상소아혈액종양

BACKGROUND: Extranodal NK/T cell lymphoma (ENKTL) is extremely rare in children, and there have been few reports on pediatric ENKTL. The purpose of this study was to investigate the clinical features and treatment outcomes of pediatric ENKTL.METHODS: The study involved a review of the medical records of eight pediatric patients who were diagnosed with ENKTL.RESULTS: Among the eight patients, three were in stage I of the disease, and five were in stages II to IV. The median follow-up period was 90.8 months. Two stage I patients were nasal type, and the other six patients were non-nasal type. Two patients died within one month of diagnosis; thus, five patients underwent chemotherapy including L-asparaginase, and one patient underwent chemotherapy without L-asparaginase. All patients showed an overall response after induction chemotherapy, with four showing a complete response (CR) and two showing a partial response (PR). Two newly diagnosed patients and one relapsed patient underwent autologous peripheral blood stem cell transplantation (aPBSCT). The five-year overall survival (OS) rate was 50%, and the five-year progression-free survival (PFS) rate was 46.9%. Ann Arbor stage was a significant prognostic factor for OS (P=0.042).CONCLUSION: Advanced-stage pediatric ENKTL was associated with a grave prognosis. However, intensive chemotherapy with L-asparaginase resulted in an overall response, and aPBSCT could be beneficial for pediatric ENKTL.

Clinical Characteristics of Pediatric Thalassemia in Korea: A Single Institute Experience

Few literatures have elaborated on the clinical characteristics of children with thalassemia from low-prevalence areas. A retrospective analysis was conducted on children genetically confirmed with thalassemia at Seoul National University Children's Hospital in Korea. Nine children (1alpha thalassemia trait, 6beta thalassemia minor, 2beta thalassemia intermedia) were diagnosed with thalassemia at median age of 4.3 yr old with median hemoglobin of 9.7 g/dL. Seven (78%) children were incidentally found to be anemic and only 2 with beta thalassemia intermedia had presenting symptoms. Five children (56%) were initially misdiagnosed with iron deficiency anemia. Despite the comorbidities due to alpha thalassemia mental retardation syndrome, the child with alpha thalassemia trait had mild hematologic profile. Children with beta thalassemia intermedia had the worst phenotypes due to dominantly inherited mutations. None of the children was transfusion dependent and most of them had no complications associated with thalassemia. Only 1 child (11%) with codon 60 (T-->A) mutation of the HBB gene needed red blood cell transfusions. He also had splenomegaly, cholelithiasis, and calvarial vault thickening. Pediatricians in Korea must acknowledge thalassemia as a possible diagnosis in children with microcytic hypochromic hemolytic anemia. High level of suspicion will allow timely diagnosis and managements.