Downhill Varices in the Hypopharynx of a Patient with a Large Thyroid Tumor: A Case Report.

Downhill varices are usually caused by superior vena cava (SVC) obstruction due to bronchogenic carcinoma or mediastinal tumors. These structures exhibit retrograde blood flow and are located in the proximal esophagus. Varices in the hypopharynx resulting from mediastinal thyroid tumor are extremely rare. A 70-year-old man with a 35-year history of a growing thyroid tumor on the right side of his neck visited a local hospital. Fine-needle aspiration cytology of the tumor revealed benign goiter. Contrast-enhanced computed tomography showed a huge tumor (13 × 10 × 5 cm) in the right to left lobe of the thyroid that extended into the mediastinum. A well-enhanced mass mimicking hypopharyngeal cancer was identified in the hypopharynx. Endoscopic examination showed varices in the postcricoid region, so biopsy was contraindicated. The preoperative diagnosis was adenomatous goiter and hypopharyngeal varices caused by obstruction of the internal jugular and brachiocephalic vein by the goiter. Total thyroidectomy was performed and the hypopharyngeal varices had disappeared by the next day. The histopathological diagnosis of the thyroid tumor was poorly differentiated carcinoma. Mediastinal thyroid tumor rarely causes downhill varices due to SVC obstruction. However, signs of SVC obstruction were absent in this case, and varices were present in the hypopharynx, not in the upper esophagus. Obstructed venous flow from the thyroid plexus might circulate via the superior laryngeal vein and cause varices in the postcricoid region. When a patient with a large mediastinal tumor has a tumor-like lesion in the hypopharynx, downhill varices should be considered before scheduling a biopsy.

A case of pheochromocytoma associated with liver abscess and intestinal pseudo-obstruction.

Pheochromocytomas can present with various symptoms. Nonspecific manifestations of pheochromocytoma include intestinal pseudo-obstruction and weight loss. Here, we present a case of pheochromocytoma in which prolonged intestinal pseudo-obstruction due to excess catecholamines was one of the factors leading to the development of a liver abscess. An 18-year-old male patient with a history of status epilepticus and severe intellectual disability was transferred to our hospital for a thorough examination of fever and constipation that had lasted for 2 months. When admitted to our hospital, he had fever, and his body mass index was 9.5 kg/m2. Upon comprehensive examination of the patient's fever, the blood culture was found positive for Bacteroides. Computed tomography showed findings of intestinal pseudo-obstruction and a low density region in the liver that indicated a liver abscess. Imaging studies also revealed a right adrenal mass and endocrinological test showed elevated plasma norepinephrine and urine normetanephrine levels. In addition, the right adrenal mass showed uptake on 123I-metaiodobenzylguanidine scintigraphy. These findings led to a definite diagnosis of pheochromocytoma. The patient was eventually diagnosed with a pheochromocytoma coexisting with a liver abscess. After treating the liver abscess with antibiotics and ultrasound-guided drainage, an adrenalectomy was performed. The pathological findings were consistent with pheochromocytoma. Postoperatively, the catecholamine excess normalized and intestinal pseudo-obstruction and weight loss improved. We suspected that prolonged intestinal pseudo-obstruction resulted in bacterial translocation and development of a liver abscess. To the best of our knowledge, this is the first report of a pheochromocytoma associated with a liver abscess. Moreover, the clinical presentation of this patient was unusual for pheochromocytoma, as the patient did not have typical symptoms such as hypertension or tachycardia, but rather presented with constipation, intestinal pseudo-obstruction, and weight loss. This case provides valuable insight regarding the impact of catecholamine excess on the intestinal tract and body weight.

Learning Curve for Endoscopic Thyroidectomy Using Video-Assisted Neck Surgery: Retrospective Analysis of a Surgeon's Experience with 100 Patients.

BACKGROUND: Endoscopic thyroidectomy offers excellent cosmetic outcomes but requires some time for surgeons to become proficient. We examined the learning curve for the first 100 patients treated by a single surgeon using a subclavian approach for video-assisted neck surgery (VANS). METHODS: We retrospectively studied the records of 100 patients (99 women, 1 man; mean age, 36.2 years) with either benign or malignant thyroid disease treated between 2016 and 2020. RESULTS: Preoperative diagnosis was papillary thyroid carcinoma (PTC) in 36 cases and other (non-PTC) in 64 cases. All patients underwent lobectomy, with additional unilateral central node dissection for patients with PTC. Mean operative time was 125 min for non-PTC cases and 129 min for PTC cases (p = 0.43); blood loss was 33.8 mL and 7.6 mL, respectively (p = 0.01). Recurrent laryngeal nerve paralysis (RNP) was observed in 12 patients (12%) and hemorrhage in 2 patients (2%). In a comparison of the first 30 cases and subsequent 70 cases, no significant differences in operative time or blood loss were evident, although tumor size was significantly greater among later non-PTC cases (32.4 mm vs. 39.5 mm, p = 0.039). RNP was significantly lower in later cases (26.7% vs. 5.7%, p = 0.003). Multivariate analysis revealed that tumor size was a significant risk factor for increased blood loss, and increased experience significantly correlated with a decrease in RNP. CONCLUSIONS: In VANS, satisfactory surgical proficiency was reached after treating 30 patients.

Clinicopathologic Characteristics and A20 Mutation in Primary Thyroid Lymphoma.

BACKGROUND: Primary thyroid lymphoma (PTL) is a rare disease frequently arising against a background of autoimmune thyroiditis. It has recently been reported that the inactivation of the NF-κB negative regulator A20 by deletion and/or mutation could be involved in the pathogenesis of subsets of B-cell lymphomas. This study investigated the clinicopathologic characteristics and A20 mutation in patients with PTL. METHODS: We analyzed the characteristics of 45 PTL patients (14 men and 31 women), with a median age of 71 (range, 35-90) years. A20 mutations were analyzed in DNA extracted from 20 samples consisting of 19 tumor tissue samples and 1 sample from Hashimoto's thyroiditis. RESULTS: Thirty-five patients (82%) had a history of Hashimoto's thyroiditis, and 29 (64%) had diffuse large B-cell lymphoma (DLBCL) and presented with larger tumors including bulky mass, elevated soluble interleukin-2 receptor levels, and a longer history of Hashimoto's thyroiditis than that of patients with mucosa-associated lymphoid tissue (MALT) lymphoma (n=16). A20 mutations were identified in 3 of 19 PTL patients (16%), in 2 of the 10 (20%) with DLBCL and in 1 of the 9 (11%) with MALT lymphoma. Interestingly, all patients with A20 mutations had Hashimoto's thyroiditis. Furthermore, they had a common missense variant in exon 3 (rs2230926 380T>G; F127C), which reduces the ability of A20 to inhibit NF-κB signaling. CONCLUSION: Our study suggests that the histological features of PTL affect clinical outcomes and that A20 mutations are related to PTL pathogenesis in some patients with Hashimoto's thyroiditis.

Case Report: A Case of Moyamoya Syndrome Associated With Multiple Endocrine Neoplasia Type 2A.

To the best of our knowledge, we report a case of MEN2A complicated by moyamoya syndrome. A 52-year-old woman presented with vertigo. Magnetic resonance angiography (MRA) revealed bilateral supraclinoid stenosis of the internal carotid artery and abnormal moyamoya-like vessels around the basal ganglia. She had a heterozygous variant of RNF213, which is the susceptibility gene for moyamoya disease. She had also previously received diagnoses of medullary thyroid carcinoma (MTC) at age 23 and left-sided pheochromocytoma (PHEO) at age 41. Genetic testing revealed heterozygosity for a mutation at codon 634 in exon 11 (TGC-TTC mutation; p.Cys634Phe) of the Ret gene. Intracranial vascular stenosis may have been caused by a genetic mutation of RNF213 and hypersecretion of catecholamines by MEN2A. Physicians should recognize that MEN2A can be present with moyamoya syndrome.

Video-assisted neck surgery (VANS) using a gasless lifting procedure for thyroid and parathyroid diseases: "The VANS method from A to Z".

PURPOSE: To describe and evaluate our video-assisted neck surgery (VANS) method for thyroid and parathyroid diseases. METHODS: We describe in detail the VANS method for enucleation, lobectomy, total (nearly total) thyroidectomy, and lymph node dissection for malignancy and Graves' disease. In collaboration with the Japan Society of Endoscopic Surgery (JSES), we evaluated several aspects of this method. The JSES evaluated the method for working-space formation and surgical complications, whereas we examined the learning curve of the surgeons, and the cosmetic satisfaction of the patients and the degree of numbness and pain they experienced. We also asked patients who underwent conventional surgery whether they would have selected VANS had it been available. RESULTS: The working space for 81.5% of the procedures in Japan was created using the gasless lifting method. The learning curve, considering both blood loss and operating time, decreased after 30 cases. Both factors improved for tumors smaller than 5 cm in diameter. Over 60% of the patients who underwent conventional surgery stated that they would have selected VANS, had it been available. Postoperative pain was worse after conventional surgery than after VANS, but neck numbness after VANS was more frequent than expected. CONCLUSIONS: The VANS method is a feasible, safe, and cost-effective procedure with clear cosmetic advantages over conventional surgery.

The Reality of Multiple Endocrine Neoplasia Type 2B Diagnosis: Awareness of Unique Physical Appearance Is Important.

BACKGROUND: Multiple endocrine neoplasia type 2B (MEN2B) is an extremely rare syndrome mainly caused by RET918 germline mutations. MEN2B typically causes medullary thyroid carcinoma (MTC), pheochromocytoma, and unique physical characteristics including mucosal neuroma, distinctive facial appearance, and Marfanoid habitus. Most patients have abdominal symptoms such as bloating, intermittent constipation, and diarrhea. MTC is the most important determinant of mortality in patients with MEN2B. Establishing the diagnosis of MEN2B at a curative stage of MTC is crucial. CASE PRESENTATION: We have encountered four patients with MEN2B. Two were hereditary cases from the same family, and two were considered de novo cases with phenotypically normal parents. Mean age at diagnosis was 25.5 years (range, 13-39 years). Although all patients had shown mucosal neuroma on the lips and tongue, in addition to gastrointestinal symptoms from infancy, diagnoses were made from symptomatic MTC even for the hereditary patients (our index case was a 14-year-old girl, whose mother was subsequently diagnosed with advanced MTC). Genetic tests for RET mutations revealed the M918T mutation in all patients. Two patients developed pheochromocytoma, two died from distant metastases of MTC, and two received treatment for multiple metastases of MTC (one with vandetanib). CONCLUSIONS: In our patients with MEN2B, prophylactic or early thyroidectomy could not be performed. The characteristic phenotype associated with MEN2B is almost always seen prior to detection of MTC or pheochromocytoma. Knowledge about the non-endocrine manifestations of MEN2B needs to be shared among pediatricians and gastroenterologists.

Expression of MRP1 and ABCG2 is associated with adverse clinical outcomes of papillary thyroid carcinoma with a solid component.

Solid variant of papillary thyroid carcinoma (PTC) is characterized by a solid component (SC) retaining classical cytological features of PTC. Despite some controversies, PTC with SC (PTCSC) cases have poor prognosis compared with well-differentiated PTC. We investigated if cancer stem cells (CSCs) may have a role in pathogenesis of PTCSC. PTCSC tumors (n=27) were histologically represented by a mixture of papillary component (PC) and varying degrees of SC involving 10% to 85% of the tumor. Immunohistochemical expression of CSC markers ABCG2 and MRP1, and HBME1 and CK19 was compared between SC and PC within each tumor in association with clinicopathological parameters. ABCG2 and MRP1 were highly expressed in SC, whereas their expression was limited or absent in PC (P=.04 and .002, respectively). In contrast, expression of HBME1 and CK19 appeared higher in PC than in SC (P=.08 and .02, respectively). Higher expression of ABCG2 was associated with higher incidence of large-sized SC (P=.01). Higher expression of MRP1 was associated with higher incidence of lymphovascular invasion (P=.049). Higher expression of ABCG2 and MRP1, and lower expression of CK19 in SC were associated with higher tumor recurrence rate (P=.02, .01, and .02, respectively), and shorter disease-free survival (P<.001 for all the variables). Our findings indicate that the tumor cells harboring CSC-like characteristics in SC could contribute to the pathogenesis of PTCSC and might account for the poor disease prognosis.

Fine needle aspiration cytology of the papillary thyroid carcinoma with a solid component: A cytological and clinical correlation.

BACKGROUND: Solid variant of papillary thyroid carcinoma is a rare subtype of papillary thyroid carcinoma (PTC) containing a solid component (SC), and thus its cytological and clinicopathological features remain elusive. We examined fine needle aspiration (FNA) cytological features of PTC with variable degrees of SC (20-80% of the tumor)(PTCSC) in comparison to well-differentiated PTC (WPTC). METHODS: Twenty-six cases of PTCSC were histologically stratified into major-SC (SC >50% of the tumor) and minor-SC (<49%) groups. Pre-operative FNA smears were compared between major-SC (n = 11) and minor-SC (n = 15) groups, and between PTCSC and WPTC (n = 39) groups. RESULTS: In FNA smears of PTCSC, the presence of cohesive solid nests, trabecular patterns, overlapping, enlarged nuclei, pleomorphism, and distinct nucleolus, and the absence of colloid and psammoma bodies were noted more often than in WPTC, while classical cytological features of PTC, such as nuclear grooves and/or pseudo-nuclear inclusions, were preserved. There was no significant difference in FNA findings between the major-SC and minor-SC groups. The presence of either solid nests or trabecular patterns, and overlapping in FNA smears of PTCSC was associated with a higher recurrence rate of the tumor (P = 0.007 and P < 0.001, respectively). CONCLUSION: PTCSC may pre-operatively be identified by detecting its characteristic cytological features in FNA smears, regardless of the proportion of SC within the tumor. Because clinical outcomes of PTCSC remain undetermined, it is imperative to postulate PTCSC as a differential diagnosis, even when classical nuclear features of PTC are present. Diagn. Cytopathol. 2017;45:391-398. © 2017 Wiley Periodicals, Inc.

Clinicopathological significance of a solid component in papillary thyroid carcinoma.

AIMS: Solid variant of papillary thyroid carcinoma (SVPTC) is characterized by a solid component (SC) involving more than 50% of the tumour with the preservation of the classical cytological features of papillary thyroid carcinoma (PTC). However, the clinical significance of SC in PTC has been rarely examined. Herein, we investigated retrospectively the clinicopathological features of PTC with various degrees (10-85%) of SC (PTCSC). METHODS AND RESULTS: Patients with PTCSC (n = 27) were stratified into SC-major (SC > 50% of the tumour) and SC-minor (SC < 49%) groups. The clinicopathological parameters were compared to the well-differentiated PTC (WPTC) group (n = 47). Both SC-minor (n = 18) and SC-major (n = 9) groups had increased incidence of a large-sized tumour, extracapsular extension and a high recurrence rate, compared to WPTC. Disease-free survival (DFS) of both SC-minor and SC-major was shorter than that of WPTC (P = 0.035 and P = 0.016, respectively). Overall survival was similar among all the groups. Univariate analysis revealed that SC was associated significantly with a recurrence rate (P = 0.018). Using multivariate analysis, SC appeared to be associated with a recurrence rate with borderline significance (P = 0.055). CONCLUSIONS: Our findings indicate that the presence of SC in PTC, regardless of the proportion, is associated with adverse clinical parameters and a shorter DFS.

An extended family with familial medullary thyroid carcinoma and Hirschsprung's disease.

Familial medullary thyroid carcinoma (FMTC) is an autosomal dominant inherited disease that has highly characteristic clinical features, including medullary thyroid carcinoma (MTC). Mutation of the RET proto-oncogene is known to be responsible for development of FMTC and for multiple endocrine neoplasia types 2A and 2B. Hirschsprung's disease is the most common form of structural intestinal obstructive disease in human newborns. Hirschsprung's disease is defined by the absence of neural crest-derived enteric ganglia along a variable length of the bowel that invariably involves the rectoanal junction. Co-segregation of FMTC and Hirschsprung's disease is uncommon; nevertheless, in 3 generations of 1 family, we observed 5 patients with FMTC, 2 patients with Hirschsprung's disease, and 1 patient with characteristics of both FMTC and Hirschsprung's disease. Moreover, a Cys620Ser mutation in RET was identified in 4 of the 8 patients. This mutation had both activating and inactivating effects on the RET (REarranged during Transfection) protein. There were individual differences in the penetrance of Hirschsprung's disease due to the RET mutation, but the penetrance of MTC was uniform and high. Genetic testing is important for making decisions about treatment and follow-up in families of this kind.

Introduction and use of video-assisted endoscopic thyroidectomy for patients in Belarus affected by the Chernobyl nuclear disaster.

INTRODUCTION: We developed video-assisted neck surgery (VANS) - a feasible, simple, and safe endoscopic thyroid procedure with cosmetic benefits - in 1998. To date, we have performed this procedure 633 times. We have also introduced the VANS method in Belarus, a country that was left contaminated by the Chernobyl nuclear disaster. METHODS: From a mass screening, nine Belarusian patients, including two with papillary carcinoma of the thyroid, were selected to undergo an operation using the VANS method, performed by a single surgeon (author Shimizu). We compared indicating factors for minimally invasive surgery, specifically the operating time and blood loss, between the Belarusian cases and the 33 most recent cases performed at our institute in Tokyo. RESULTS: The procedures in Belarus were performed under very different working conditions than in Japan. However, operating time and blood loss improved for the Belarusian cases as the surgeon gained experience in this environment; all the cosmetic outcomes were excellent. Subsequently, over a 2-year period, surgeons in Belarus performed the VANS method, with modification, for 29 cases of thyroid tumor. CONCLUSION: The VANS method is easily learned by inexperienced surgeons without major technical problems.

Identical germline mutations in the TMEM127 gene in two unrelated Japanese patients with bilateral pheochromocytoma.

OBJECTIVE: Recently, TMEM127 was shown to be a new pheochromocytoma susceptibility gene; this is consistent with its function as a tumour suppressor gene (Journal of Clinical Endocrinology and Metabolism, 2009, 94, 2817). Most pheochromocytomas arise from the adrenal medulla, and in approximately half of the cases, the tumours are bilateral (Journal of Clinical Endocrinology and Metabolism, 2009, 94, 2817; Journal of the American Medical Association, 2004, 292, 943; Human Mutation, 2010, 31, 41; Science, 2009, 325, 1139). The aim of the present study was to determine whether TMEM127 mutations are involved in the pathogenesis of pheochromocytomas/paragangliomas in Japanese subjects. PATIENTS AND METHODS: For this study, 74 unrelated patients with pheochromocytoma/paraganglioma who tested negative for mutations and deletions in RET, VHL, SDHB and SDHD were recruited through a multi-institutional collaborative effort in Japan. The TMEM127 gene sequence was determined in their germline DNA, and tumour DNA was analysed for the loss of heterozygosity. In addition, their TMEM127 gene sequences were compared with sequences from 114 normal healthy, ethnically matched controls. RESULTS: Among the 74 eligible patients, two unrelated patients (2·7%) with bilateral adrenal pheochromocytoma were found to have an identical germline TMEM127 mutation (c.116_119delTGTC, p.Ile41ArgfsX39) associated with 2q deletion loss of heterozygosity, which was also previously described in a Brazilian case (Journal of the American Medical Association, 2004, 292, 943). We also determined that none of the 114 normal healthy controls had this deletion mutation. CONCLUSION: This is the first report showing that TMEM127 mutation plays a pathological role in pheochromocytoma in an Asian population. Although our surveillance is limited, the prevalence and the phenotype of this gene mutation appear to be similar to those reported in previous studies.

Proteomic profiling of thyroid papillary carcinoma.

Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy. We performed shotgun liquid chromatography (LC)/tandem mass spectrometry (MS/MS) analysis on pooled protein extracts from patients with PTC and compared the results with those from normal thyroid tissue validated by real-time (RT) PCR and immunohistochemistry (IHC). We detected 524 types of protein in PTC and 432 in normal thyroid gland. Among these proteins, 145 were specific to PTC and 53 were specific to normal thyroid gland. We have also identified two important new markers, nephronectin (NPNT) and malectin (MLEC). Reproducibility was confirmed with several known markers, but the one of two new candidate markers such as MLEC did not show large variations in expression levels. Furthermore, IHC confirmed the overexpression of both those markers in PTCs compared with normal surrounding tissues. Our protein data suggest that NPNT and MLEC could be a characteristic marker for PTC.

Multiple endocrine neoplasia type 1 in Japan: establishment and analysis of a multicentre database.

OBJECTIVE: Multiple endocrine neoplasia type 1 (MEN1) is less well recognized in Asian countries, including Japan, than in the West. The clinical features and optimal management of MEN1 have yet to be clarified in Japan. The aim of this study was to clarify the clinical features of Japanese patients with MEN1. DESIGN/PATIENTS: We established a MEN study group designated the 'MEN Consortium of Japan' in 2008, and asked physicians and surgeons to provide clinical and genetic information on patients they had treated. Of 680 registered patients, 560 were analysed. MEASUREMENTS: Clinical and genetic features of Japanese patients with MEN1 were examined. RESULTS: Primary hyperparathyroidism, gastroenteropancreatic neuroendocrine tumours (GEPNET), and pituitary tumours were seen in 94·4%, 58·6% and 49·6% of patients, respectively. The prevalence of insulinoma was higher in the Japanese than in the West (22%vs 10%). In addition, 37% of patients with thymic carcinoids were women, while most were men in western countries. The MEN1 mutation positive rate was 91·7% in familial cases and only 49·3% in sporadic cases. Eight novel mutations were identified. Despite the availability of genetic testing for MEN1, the application of genetic testing, especially presymptomatic diagnosis for at-risk family members appeared to be insufficient. CONCLUSIONS: We established the first extensive database for Asian patients with MEN1. Although the clinical features of Japanese patients were similar to those in western countries, there were several characteristic differences between them.

Photodynamic identification of human parathyroid glands with 5-aminolevulinic acid.

Tumors synthesize fluorescent and photosensitizing endogenous protoporphyrin after administrations of 5-aminolevulinic acid (5-ALA). Localization of tumors and tumor-like lesions in various organs that are labeled with fluorescing porphyrins has thus developed into a diagnostic method. Intraoperative photodynamic detection of malignant gliomas is the most common application, and has been widely performed since 1998. Although several methods to identify parathyroid glands have been employed, photodynamic methods have not yet been used for this application. In 2004, Shimizu et al. showed that human parathyroid glands could be identified photodynamically with 5-ALA. We have performed photodynamic identification of human parathyroid glands in an additional 19 cases. In hyperparathyroidism, detection of morbid parathyroid glands is extremely important. On the other hand, the identification and preservation of normal parathyroid glands is important for preventing hypoparathyroidism after thyroid surgery. Our method allows the visualization of both morbid and normal parathyroid glands. We believe that intraoperative photodynamic identification of human parathyroid glands is feasible and practical, allowing less-invasive, more-precise neck surgery.

Overcoming graft rejection in heavily transfused and allo-immunised patients with bone marrow failure syndromes using fludarabine-based haematopoietic cell transplantation.

Allogeneic haematopoietic cell transplantation (HCT) can cure a variety of non-malignant haematological disorders. Although transplant outcomes for selected patients with severe aplastic anaemia (SAA) and paroxysmal nocturnal haemoglobinuria (PNH) have improved, older age, allo-immunisation from transfusions, prior immunosuppressive therapy and a prolonged time from diagnosis to transplantation are associated with worse outcome. Because of its potent immunosuppressive effects, we investigated a fludarabine-based non-myeloablative conditioning regimen in patients with transfusion-dependent non-malignant haematological disorders at increased risk for graft rejection with conventional transplant conditioning. Twenty-six patients with transfusion dependent/anti-thymocyte globulin (ATG)-refractory SAA, PNH or pure red cell aplasia underwent HCT from a human leucocyte antigen (HLA)-compatible relative. Transplant conditioning consisted of cyclophosphamide (120 mg/kg) and fludarabine (125 mg/m2) with or without ATG. Ciclosporine, alone or combined with mycophenolate mofetil or methotrexate, was used as graft-versus-host disease (GVHD) prophylaxis. All patients achieved durable engraftment and transfusion-independence. Twenty-four of 26 patients are alive at a median of 21 months following transplantation. Although a high cumulative incidence of acute (65% grades II-IV, 54% grades III-IV) and chronic GVHD (56%) was observed, only one patient died from transplant-related causes (cumulative incidence 7%). These data show that HCT following fludarabine-based non-myeloablative conditioning results in durable engraftment and excellent survival in SAA and PNH patients at high risk for graft rejection.

Cell labeling for magnetic resonance imaging with the T1 agent manganese chloride.

There is growing interest in using MRI to track cellular migration. To date, most work in this area has been performed using ultra-small particles of iron oxide. Immune cells are difficult to label with iron oxide particles. The ability of adoptively infused tumor specific T cells and N cells to traffic to the tumor microenvironment may be a critical determinant of their therapeutic efficacy. We tested the hypothesis that lymphocytes and B cells would label with MnCl2 to a level that would allow their detection by T1-weighted MRI. Significant signal enhancement was observed in human lymphocytes after a 1 h incubation with 0.05-1.0 mM MnCl2. A flow cytometry-based evaluation using propidium iodide and Annexin V staining showed that lymphocytes did not undergo apoptosis or necrosis immediately after and 24 h following a 1 h incubation with up to 1.0 mM MnCl2. Importantly, NK cells and cytotoxic T cells maintained their in vitro killing capacity after being incubated with up to 0.5 mM MnCl2. This is the first report to describe the use of MnCl2 to label lymphocytes. Our data suggests MnCl2 might be an alternative to iron oxide cell labeling for MRI-based cell migration studies.