Nationwide study of pediatric B-cell precursor acute lymphoblastic leukemia with chromosome 8q24/MYC rearrangement in Japan.

BACKGROUND: Rearrangements of chromosome 8q24/MYC (8q24/MYC-r), resulting from t(8;14)(q24;q32), t(2;8)(p11;q24), or t(8;22)(q24;q11), are mainly associated with Burkitt lymphoma/leukemia (BL) and rarely observed in patients with B-cell precursor acute lymphoblastic leukemia (BCP-ALL). The characteristics of BCP-ALL with 8q24/MYC-r are poorly understood. PROCEDURE: A retrospective nationwide study of data from patients with pediatric BCP-ALL with 8q24/MYC-r in Japan was conducted to clarify the clinical and biological characteristics associated with 8q24/MYC-r BCP-ALL. RESULTS: Ten patients with BCP-ALL with 8q24/MYC-r, including three with double-hit leukemia (DHL) (two with t(8;14)(q24;q32) and t(14;18)(q32;q21) and one with t(8;14) and t(3;22)(q27;q11)), were identified. Patients with BCP-ALL with 8q24/MYC-r had higher median age and uric acid and lactate dehydrogenase levels, than those without 8q24/MYC-r. All patients were initially treated with ALL-type chemotherapy; however, four, including one with DHL, were switched to BL-type chemotherapy, based on cytogenetic findings. One patient relapsed after standard-risk ALL-type chemotherapy, and two patients with DHL did not attain complete remission with chemotherapy; all three died within 11 months. The other seven patients treated with BL-type or high-risk ALL-type chemotherapy are alive without disease. CONCLUSIONS: The clinical and laboratory features of BL with IG-MYC rearrangement, displaying a BCP immunophenotype (Wagener et al. and Herbrueggen et al. termed it as pre-BLL), are similar to those of BCP-ALL with 8q24/MYC-r. Low-risk ALL-type chemotherapy may not be appropriate for them, and further studies are required to establish an adequate therapeutic strategy. Further studies of DHL to identify new treatment strategies are also needed.

Ectopic neuroblastoma in monozygotic twins with different ages of onset: possible twin-to-twin metastasis in utero with distinct genetic alterations after birth.

We describe neuroblastoma (NB) in monozygotic twins whose ages at the onset of the disease had a 3-year interval. The primary tumor site of twin 1 was the adrenal gland, whereas that of twin 2 was the jejunum/mesentery. MYCN amplification, DNA index, ALK mutation, and copy number alterations of DNA were different between each primary tumor. NB in ectopic sites may have resulted from twin-to-twin metastasis through vascular anastamoses in the placenta. The pathogenesis of this NB involved a premalignant stage of NB during the fetal development and subsequent molecular alterations after birth, resulting in NBs that were phenotypically similar but genetically different.

Outcomes of regenerative treatment for over 200 patients with tympanic membrane perforation.

OBJECTIVE: To evaluate outcomes of a regenerative treatment (RT) for over 200 patients with tympanic membrane perforation (TMP). The RT-TMP method involves a gelatin sponge, basic fibroblast growth factor (bFGF) and fibrin glue. METHODS: The study population included 216 patients and 234 ears (male: female =100:116; age 1-93 years). All enrolled patients were treated with RT-TMP in which TMP edges were disrupted mechanically and a gelatin sponge immersed in bFGF was inserted into the perforation. Fibrin glue was then dripped over the sponge. Patient outcomes including TMP closure rates, change in hearing level, and complications were obtained from retrospective medical chart reviews. The TMP was examined three or more weeks after surgery. The treatment was repeated up to 4 times until complete TMP closure was achieved. RESULTS: After mechanical disruption, the perforation size was Grade I, ≤1/3 of entire TM area in 22 ears (9.4 %), Grade II, 1/3-2/3 of entire TM in 77 ears (32.9 %) and Grade III, ≥2/3 of entire TM area in 135 ears (57.7 %). The overall TMP closure rates were 97.0 % (227/234). Complete TMP closure was achieved in 68.8 % (161/234), 22.6 % (53/234), 4.7 % (11/234) and 0.9 % (2/234) of ears after 1, 2, 3 and 4 treatments, respectively. In 7 of 234 ears (3.0 %), the TMPs were not closed completely after 4 treatments. There was no correlation between TMP size after mechanical disruption and number of treatments required to achieve complete closure (Fisher's exact test p = 0.70). The mean air-conduction hearing threshold at low frequency improved from 57.3 ± 16.7 dB before treatment to 37.3 ± 16.0 dB (p < 0.0001) after closure of TMPs. For middle and high frequencies, the improvement was 49.0 ± 19.3 dB to 36.9 ± 17.9 dB (p < 0.0001) and 57.7 ± 22.9 dB to 49.2 ± 23.3 dB (p < 0.0001), respectively. The mean air-bone gaps also improved significantly, and were within 10 dB at 250 Hz, 500 Hz and 1 kHz, and 11 dB at 2 kHz. One or more complications occurred in 32 patients (32/216; 14.8 %). The most common complication was formation of an epithelial pearl (16 ears; 6.8 %), followed by severe TM retraction (9 ears; 3.8 %) and otitis media with effusion (6 ears; 2.6 %). There were no serious complications that caused deterioration of the patient's general condition. CONCLUSION: Our results showed that RT-TMP had high success rates for TMP closure and good hearing improvement and produced no severe complications that could affect general health status. This novel therapy is simple, safe and minimally invasive, and could help improve the quality of life in patients with TMP.

A case with sacrococcygeal primitive myxoid mesenchymal tumor of infancy: a case report and review of the literature.

A girl, aged 19 months, presented with a sacrococcygeal tumor that developed at 5 months after birth and gradually enlarged. Serum tumor marker levels were negative. Ultrasound imaging showed abundant blood flow in the tumor. However, neither computed tomography (CT) nor magnetic resonance imaging (MRI) showed contrast agent incorporation. The surgically resected tumor consisted of immature cells with myxoid stroma and proliferating small blood vessels. Immunostaining showed extensive vimentin expression. However, smooth muscle actin, muscle-specific actin, and S-100 protein expression was negative. Neither the ETV6-NTRK3 fusion gene nor the FUS gene rearrangement was detected. Thus, the patient was diagnosed with a primitive myxoid mesenchymal tumor of infancy. This tumor primarily consisted of a mucosal stroma with a low absorption on CT, a low signal on T1-weighted MRI, and a high signal on T2-weighted MRI. A diagnosis of primitive myxoid mesenchymal tumor of infancy should be considered in cases of soft tissue tumors in infants that show prominent vascularity but little contrast enhancement on MRI or CT.

Therapy-related Ph+ leukemia after both bone marrow and mesenchymal stem cell transplantation for hypophosphatasia.

Bone marrow (BM) transplantation (BMT) is one of the treatment strategies for congenital metabolic disease, but leukemia secondary to intensive cytoreductive treatment is a major concern. Besides BM cells, mesenchymal stem cells (MSC) are also used for transplantation. An 8-month-old girl with hypophosphatasia underwent transplantation of haploidentical BM cells followed by two transplants of MSC obtained from her father to facilitate osteogenesis. Fludarabine(Flu)/cyclophosphamide (CPA)/anti-thymocyte globulin were used for myeloablative conditioning, but the patient developed therapy-related leukemia harboring t(9;22)(q34;q11.2); minor BCR-ABL (t-leukemia with Ph) at the age of 32 months. At the age of 40 months she underwent a second BM and third MSC transplant from the same donor. Thereafter, she achieved complete histological and molecular remission. The present case suggests that the combination of cytotoxic agents (Flu/CPA) and MSC led to t-leukemia with Ph as a consequence of chromosome instability and suppression of host anti-tumor immunity.

Long-term exposure to high-concentration dexamethasone in the inner ear via intratympanic administration.

The first-line treatment for inner ear disorders is usually oral/systemic steroids. Intratympanic steroid therapy is an alternative option; however, it requires multiple office visits owing to the short residence time of steroids in the inner ear (systemic: 24 h, intratympanic: 2-3 h). Therefore, intratympanic injections of higher steroid concentrations could result in longer drug exposure, providing better treatment outcomes. This study aimed to develop a prototype for high-concentration steroids and examine their safety and feasibility in vivo. Using wild-type Institute for Cancer Research mice, high-concentration steroids (50 mg/mL dexamethasone), typical steroid concentrations (3.3 mg/mL dexamethasone), and sterile saline were administrated into the middle ear cavity via tympanic membrane injection. Auditory brainstem response analysis, vestibular function tests, and morphological analyses were performed to examine the safety and utility of High-conc Dex. One month post-injection, the frequency-averaged auditory brainstem response thresholds of high-dose dexamethasone-treated mice were not significantly different from those of low-dose dexamethasone- and saline-treated mice at all tested frequencies. Furthermore, the total points on vestibular function tests were similar between the three groups. Morphologically, no damage to the inner ear/middle ear mucosa was observed in all groups. Two months post-injection, dexamethasone could still be detected in the high-dose dexamethasone group. Altogether, our data successfully demonstrates the feasibility and safety of high-dose dexamethasone for in vivo use in the middle ear and ensure that the drug localizes to the inner ear. Further research is warranted to develop this new treatment strategy and further characterize its effects in vivo.

Diagnosing Middle Ear Malformation by Pure-Tone Audiometry Using a Three-Dimensional Finite Element Model: A Case-Control Study.

BACKGROUND: Hearing loss caused by middle ear malformations is treated by tympanoplasty to reconstruct the acoustic conduction system. The mobility of the ossicles plays a crucial role in postoperative success. However, identifying the location of ossicular malformation based solely on preoperative audiograms is challenging due to the complex relationship between fixation location, deformity levels, and ossicular mobility. METHODS: Middle ear finite element models for simulating ossicular malformations were created, and the results were compared with the actual preoperative audiograms. RESULTS: This approach objectively diagnosed ossicular fixation and disarticulation, bypassing traditional criteria reliant on physician examination or imaging. CONCLUSION: This study suggests that future research should focus on developing a diagnostic framework utilizing large-scale data.

Successful management of temporary veno-venous extracorporeal membrane oxygenation for a pediatric lung transplant recipient with bronchiolitis obliterans syndrome awaiting lung re-transplantation: a case report.

BACKGROUND: The use of extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation is an uncommon strategy in Japan owing to the severe donor shortage and absence of urgent allocation policy. Moreover, the use of veno-venous (VV) ECMO for immunosuppressed patients is controversial; thus, applying ECMO to patients who await lung re-transplantation is challenging. CASE PRESENTATION: A 16-year-old lung transplant recipient with grade 3 bronchiolitis obliterans syndrome was waitlisted for lung re-transplantation. Eleven months later, he fell into severe respiratory acidosis with hypercapnia, which were not resolved with mechanical ventilation. VV ECMO was introduced to minimize lung stress and strain. Tracheostomy was additionally performed on day 5 after the start of ECMO, and respiratory condition swiftly improved; hence, the weaning process from VV ECMO began on day 9. Rehabilitation became implementable, and bilateral re-lung transplantation was successfully performed 6 months after the ECMO treatment. No critical complication related to the precedent use of ECMO was noted. CONCLUSIONS: VV ECMO can be a feasible treatment option even for lung transplant candidates awaiting re-transplantation for a prolonged period. Introduction of ECMO and tracheostomy in the early deterioration stage may be crucial to successful subsequent patient management.

[A Surgical Case of Currarino Syndrome with Syringomyelia].

Currarino syndrome is characterized by a triad of anorectal malformations, sacral defects, and presacral masses. Although it is not extremely rare, this report presents a surgical case of Currarino syndrome with syringomyelia and discusses related literature. The patient is a girl, aged 2 years and 2 months, who presented with marked constipation, chronic cystitis, and lower limb weakness. After examining the patient through magnetic resonance imaging, we diagnosed her with rectal compression due to meningocele and syringomyelia. The base of the meningocele was detached, and the spinal cord was untethered. One week after surgery, her lower limb weakness and constipation improved. Following up on symptoms and performing imaging is essential to determine a treatment plan for Currarino syndrome. (Received 28 February, 2023; Accepted 22 March, 2023; Published 1 August, 2023).

Survey of Food Intake in Patients with Abdominal Aortic Aneurysm.

Abdominal aortic aneurysm (AAA) is a vascular disease that involves asymptomatic progressive expansion of the abdominal aorta. Aneurysm rupture is associated with a high mortality rate. Dietary conditions may be associated with the development and rupture of AAA. However, the relationship between nutrition and AAA is not completely understood. In this study, a nutrition survey was conducted using a brief self-administered diet history questionnaire (BDHQ) to evaluate the relationship between AAA and dietary habits. One-hundred and twenty-six Japanese people participated in the nutrition survey. Food intake status was analyzed in four groups: the analyzed group-1 (all men), analyzed group-2 (men with smoking history), analyzed group-3 (all women) and analyzed group-4 (women without smoking history). In group-2 and group-3, the intake of citrus fruits was significantly lower in the AAA group than in the non-AAA group. In group-2, the intake of soybean and soybean products was significantly lower in the AAA group than in the non-AAA group. In analyzed group-3, the intake of other vegetables (vegetables except for green and yellow vegetables and soybeans) and seafood was significantly lower in the AAA group than in the non-AAA group. This study suggests that AAA onset may be associated with low intake of fruits, soybeans, vegetables, and seafood.

Outcome in 146 patients with paediatric acute myeloid leukaemia treated according to the AML99 protocol in the period 2003-06 from the Japan Association of Childhood Leukaemia Study.

The acute myeloid leukaemia (AML) 99 trial conducted previously in Japan for the treatment of de novo paediatric AML showed excellent results, with a 5-year overall survival (OS) and event-free survival (EFS) of 75·6% and 61·6%, respectively. To examine reproducibility of these results in another cohort, the outcome of 146 newly diagnosed AML paediatric patients prospectively registered in the Japan Association of Childhood Leukaemia Study (JACLS) from 2003 to 2006 was compared to that of 240 patients in the original AML 99 clinical trial. The 5-year EFS and OS achieved in the new cohort was 66·7 ± 4·0% and 77·7 ± 8·0% respectively, which were comparable to those obtained in the original AML 99 clinical trial, although less frequent core-binding factor (CBF) AML (29·5% vs. 37%) and an almost equal frequency of allogeneic haematopoietic stem cell transplantation (allo-HSCT) during first complete remission (16·5% vs. 19%) were observed. The 5-year EFS in patients with a normal karyotype (NK) (n = 35, 54·9 ± 15·1%) was inferior in the present cohort when compared to the original AML99 trial. This study confirmed the excellent outcome of the original AML99 protocol.

Reduced-intensity conditioning in unrelated donor cord blood transplantation for familial hemophagocytic lymphohistiocytosis.

Familial hemophagocytic lymphohistiocytosis (FHL) is a disorder of immune homeostasis characterized by fever, cytopenias, hepatosplenomegaly, and coagulopathy. We studied the outcomes of 13 FHL patients who underwent the first unrelated cord blood transplantation (UCBT) after non-myeloablative conditionings. The major regimen consisted of fludarabine (FLU; n = 12)+melphalan (MEL; n = 11)± low-dose total body irradiation (TBI 2-4 Gy; n = 6). The median age at presentation and period to UCBT were 6 and 5 months, respectively. Central nervous system (CNS) disease developed in one infant at diagnosis, and in two others until UCBT. HLH activity was controlled in all but one at the time of UCBT. Ten patients had early engraftment on median day 21 with no grade >2 treatment-related toxicity and two controllable grade >2 acute GVHD. Two patients with early rejection successfully underwent subsequent UCBT after myeloablative conditioning. Two others had late graft failure following mixed donor chimerism. Two deaths occurred from HLH; early liver failure and late CNS disease. Of 11 FLU+MEL-conditioned patients, the frequency of disease-free complete engraftment was higher for MEL (≥120 mg/m(2) )+TBI, or high-dose MEL (180 mg/m(2) ) than for others (83% vs. 25%, p = 0.036). The FLU+MEL-based non-myeloablative regimen was acceptable for FHL infants undergoing UCBT, although further studies will be needed for confirmation.

Predictive factors of acute sensorineural hearing loss in adult Japanese patients for clinical application by primary care doctors: a cross-sectional study.

BACKGROUND: Several methods are used for hearing loss screening; however, their benefits are uncertain. In this study, we aimed to determine the predictive factors of acute sensorineural hearing loss for clinical application by primary care doctors. METHODS: This retrospective, cross-sectional study included 365 patients with acute sensorineural hearing loss without prior therapy. The patients' clinical data, demographic information, and medical histories were obtained, and they were asked about comorbidities. In addition, we assessed lifestyle factors such as stress level, alcohol consumption, marital status, and socioeconomic level. Logistic regression analysis was performed to investigate the diagnostic predictive ability of the selected factors associated with acute sensorineural hearing loss. The hearing levels of all patients were evaluated using pure tone audiometry. RESULTS: We identified significant predictive factors for acute sensorineural hearing loss. The absence of hyperacusis was a predictive factor for sudden sensorineural hearing loss. Younger age, female sex, and marital status were predictive factors for acute low-tone hearing loss. High body mass index, high socioeconomic level, low alcohol consumption, high stress level, hyperacusis, and vertigo/dizziness were predictive factors for Ménière's disease. High body mass index and ear fullness were predictive factors for perilymph fistula. Low stress level was a predictive factor for acoustic tumours. CONCLUSIONS: Our findings can be used to distinguish between the types of acute sensorineural hearing loss. Symptoms, physical status, and lifestyle factors identified during this study are useful markers for predicting acute sensorineural hearing loss occurrence.

Cavernous hemangioma of the accessory parotid gland.

We report a rare case of a hemangioma arising from the accessory parotid gland. The patient, a 45-year-old woman, complained of a right midcheek mass. Magnetic resonance imaging showed a well-defined mass located in the right buccal space, anterior to the masseter muscle, and adjacent to the Stensen duct. The mass had high T2-weighted signal intensity and showed strong patchy enhancement with gadolinium. This mass was surrounded by a common capsule with the accessory parotid gland. These findings indicated a hemangioma originating from the accessory parotid gland. The mass was completely removed by an intraoral approach without postoperative facial palsy, skin deformity, and difficulty in secreting saliva. Histologic examination of the tumor revealed multiple, thin-walled, and dilated blood vessels, confirming the diagnosis of a cavernous hemangioma. Magnetic resonance imaging was extremely useful in diagnosing the mass as a hemangioma before surgery, clarifying relationships between the mass and adjacent structures and determining the surgical approach to the mass.

Hearing Outcomes and Complications of Cochlear Implantation in Elderly Patients over 75 Years of Age.

OBJECTIVE: Populations are aging in many countries, and the proportion of elderly people with severe to profound hearing loss is increasing in parallel with the increasing average life span. The objective of this study was to investigate the outcomes of cochlear implant (CI) surgery in elderly patients compared to those in younger patients. METHODS: The outcomes of CI surgery were retrospectively investigated for 81 adults (32 men and 49 women) who underwent CI surgery at our hospital. They were divided according to age at the time of implantation into the younger group (<75 years of age; n = 49) or elderly group (≥75 years of age; n = 32). RESULTS: The mean sentence recognition score on the CI-2004 Japanese open-set test battery (±standard deviation) was 82.9% ± 24.1 in the younger group and 81.9% ± 23.2 in the elderly group, with no significant difference between the groups (Mann-Whitney U test). The incidence of major complications that required surgical treatment was not significantly different between the groups (4.1% vs. 6.2%, respectively). Thus, there were no severe complications that could affect general health status in either group. Three patients in each group died for reasons unrelated to CI surgery during follow-up. The proportion of patients who were alive and continued to use the CI five years after surgery was 92.8% and 91.5%, respectively. CONCLUSION: Our results show good speech recognition and a low incidence of major complications in elderly patients. This comprehensive report on the outcomes of CI surgery in elderly patients will be helpful to the elderly with severe to profound hearing loss when deciding whether to undergo CI surgery.

Multicenter phase III trial of regenerative treatment for chronic tympanic membrane perforation.

OBJECTIVE: To evaluate the efficacy and safety of regenerative treatment for tympanic membrane perforation (TMP) using gelatin sponge, basic fibroblast growth factor (bFGF), and fibrin glue. METHODS: This was a multicenter, non-randomized, single-arm study conducted at tertiary referral centers. Twenty patients with chronic TMP (age 23-78 years, 6 males, 14 females) were registered from three institutions. All treated patients were included in the safety analysis population. The edges of the TMP were disrupted mechanically by myringotomy and several pieces of gelatin sponge immersed in bFGF were placed and fixed with fibrin glue to cover the perforation. The TMP was examined 4 ± 1 weeks later. The protocol was repeated up to four times until closure was complete. The main outcome measures were closure or a decrease in size of the TMP, hearing improvement, and air-bone gap evaluated 16 weeks after the final regenerative procedure (FRP). Adverse events (AEs) were monitored throughout the study. RESULTS: Total closure of the TMP at 16 weeks was achieved in 15 out of 20 patients (75.0%, 95% confidence interval [CI]: 50.9%-91.3%) and the mean decrease in size was 92.2% (95%CI: 82.9%-100.0%). The ratio of hearing improvement and the air-bone gap at 16 weeks after FRP were 100% (20/20; 95%CI: 83.2%-100%) and 5.3 ± 4.2 dB (p <0.0001), respectively. Thirteen out of 20 patients (65.0%) experienced at least one AE, but no serious AEs occurred. CONCLUSION: The results indicate that the current regenerative treatment for TMP using gelatin sponge, bFGF, and fibrin glue is safe and effective.

Mutations in the ribosomal protein genes in Japanese patients with Diamond-Blackfan anemia.

BACKGROUND: Diamond-Blackfan anemia is a rare, clinically heterogeneous, congenital red cell aplasia: 40% of patients have congenital abnormalities. Recent studies have shown that in western countries, the disease is associated with heterozygous mutations in the ribosomal protein (RP) genes in about 50% of patients. There have been no studies to determine the incidence of these mutations in Asian patients with Diamond-Blackfan anemia. DESIGN AND METHODS: We screened 49 Japanese patients with Diamond-Blackfan anemia (45 probands) for mutations in the six known genes associated with Diamond-Blackfan anemia: RPS19, RPS24, RPS17, RPL5, RPL11, and RPL35A. RPS14 was also examined due to its implied involvement in 5q- syndrome. RESULTS: Mutations in RPS19, RPL5, RPL11 and RPS17 were identified in five, four, two and one of the probands, respectively. In total, 12 (27%) of the Japanese Diamond-Blackfan anemia patients had mutations in ribosomal protein genes. No mutations were detected in RPS14, RPS24 or RPL35A. All patients with RPS19 and RPL5 mutations had physical abnormalities. Remarkably, cleft palate was seen in two patients with RPL5 mutations, and thumb anomalies were seen in six patients with an RPS19 or RPL5 mutation. In contrast, a small-for-date phenotype was seen in five patients without an RPL5 mutation. CONCLUSIONS: We observed a slightly lower frequency of mutations in the ribosomal protein genes in patients with Diamond-Blackfan anemia compared to the frequency reported in western countries. Genotype-phenotype data suggest an association between anomalies and RPS19 mutations, and a negative association between small-for-date phenotype and RPL5 mutations.

New bone formation by allogeneic mesenchymal stem cell transplantation in a patient with perinatal hypophosphatasia.

Mesenchymal stem cells (MSCs) can show osteogenic differentiation capability when implanted in vivo, as well as cultured in vitro; therefore we attempted to use allogeneic MSCs for an 8-month-old patient with hypophosphatasia. MSCs were obtained by culture expansion of fresh marrow from the patient's father. Some of the MSCs were further cultured under osteogenic conditions on a culture dish or porous hydroxyapatite ceramics, resulting in cultured osteoblasts and osteogenic constructs, respectively. The MSCs and osteoblasts were injected into the patient, and the constructs were implanted locally. After traditional bone marrow transplantation, the MSCs, osteoblasts, and osteogenic constructs were used for treatment and to improve the patient's respiratory condition and skeletal abnormality. The condition worsened again, and an MSC booster shot was administered. At the same time, the construct was retrieved. The respiratory condition improved, and the retrieved construct showed de novo bone derived from both donor and patient cells. We demonstrated the importance of allogeneic MSC transplantation for hypophosphatasia and the constructs as an alternative to bone fragments that provided further osteogenic capability in the patient.

Pure red cell precursor toxicity by linezolid in a pediatric case.

Linezolid (LZD)-induced myelosuppression has been reported in adults; however, LZD-induced pure red cell precursor toxicity rarely occurs. A 2-year-old boy diagnosed with infective endocarditis by Streptococcus mitis received LZD after developing resistance to multiple antibiotics. Although his infective symptoms were improved by LZD, progressive anemia was noticed 2 weeks after LZD therapy. Four weeks after LZD administration, his hemoglobin level was 6.5 g/dL and reticulocytes less than 0.1%. Bone marrow examination revealed markedly decreased erythropoiesis with cytoplasmic vacuolation of erythroblasts. Anemia recovered 19 days after cessation of LZD. Elevated protoporphyrin and a high LZD level in the blood suggested that mitochondrial disturbance by high-dose and long-term treatment with LZD may have been responsible for LZD-induced pure red cell precursor toxicity.