Lymphoreticular Research Articles

Uncommon Presentation of Non-Hodgkin's Lymphoma of Maxillary Sinus: A Case Report

Non-Hodgkin’s Lymphoma is a group of neoplasms that originate from the cells of the lymphoreticular system. In 40% of cases, it arises from extranodal sites. The nasal cavities and paranasal sinuses are rarely affected by primary Non hodgkin’s lymphoma. We report the case of a 60-year-old man admitted for Non-Hodgkin’s Lymphoma of maxillary sinus. CT scan demonstrated an extensive lesion destroying the medial and anterior walls. The patient received 6 cycles of the chemotherapy. The follow-up for the last 1 year was normal without recurrence. The difficulty encountered in the diagnosis of this clinicopathological entity owing to its radiological and clinical expression, particularly the evolution was discussed. Though rare, the signs and symptoms of the case suggest that Non hodgkin’s lymphoma should be considered in the differential diagnosis of nasal cavity lesions.

Blood transmission studies of prion infectivity in the squirrel monkey (Saimiri sciureus): the Baxter study.

Four secondary transmissions of variant Creutzfeldt-Jakob disease (vCJD) infectivity have been associated with the transfusion of nonleukoreduced red blood cells collected from vCJD patients during the asymptomatic phase of the disease. Establishing efficient experimental models for assessing the risk of future transmissions of vCJD infectivity via blood transfusion is of paramount importance in view of a study of archived appendix samples in which the prevalence of asymptomatic vCJD infection in the United Kingdom was estimated at approximately 1 in 2000 of the population. In this study, we investigated transmission of vCJD and sporadic CJD (sCJD) infectivity from blood using the squirrel monkey, which is highly susceptible to experimental challenge with human prion disease. Whole blood collected from vCJD- and sCJD-infected squirrel monkeys was transfused at multiple time points into recipient squirrel monkeys. Blood recipients were euthanized approximately 7 years after their first blood transfusion. No clinical or pathologic signs of a prion disease were observed in either the sCJD- or the vCJD-transfused monkeys, and immunohistochemistry and biochemical investigations showed no PrP(TSE) in central nervous system or lymphoreticular tissues. Similarly, monkeys inoculated intracerebrally (IC) and intravenously (IV) with either buffy coat or plasma from vCJD and sCJD patients failed to develop disease. However, white blood cells from a chimpanzee-passaged strain of human Gerstmann-Sträussler-Scheinker (GSS) disease transmitted autopsy-proven disease to two IC-inoculated monkeys after incubation periods of 34 and 39 months. Blood transmits GSS but not sCJD or vCJD infectivity to IC- or IV-inoculated squirrel monkeys within a 7-year observation period.

Post-conversion sialylation of prions in lymphoid tissues

Sialylated glycans on the surface of mammalian cells act as part of a "self-associated molecular pattern," helping the immune system to recognize "self" from "altered self" or "nonself." To escape the host immune system, some bacterial pathogens have evolved biosynthetic pathways for host-like sialic acids, whereas others recruited host sialic acids for decorating their surfaces. Prions lack nucleic acids and are not conventional pathogens. Nevertheless, prions might use a similar strategy for invading and colonizing the lymphoreticular system. Here we show that the sialylation status of the infectious, disease-associated state of the prion protein (PrP(Sc)) changes with colonization of secondary lymphoid organs (SLOs). As a result, spleen-derived PrP(Sc) is more sialylated than brain-derived PrP(Sc). Enhanced sialylation of PrP(Sc) is recapitulated in vitro by incubating brain-derived PrP(Sc) with primary splenocytes or cultured macrophage RAW 264.7 cells. General inhibitors of sialyltranserases (STs), the enzymes that transfer sialic acid residues onto terminal positions of glycans, suppressed extrasialylation of PrP(Sc). A fluorescently labeled precursor of sialic acid revealed ST activity associated with RAW macrophages. This study illustrates that, upon colonization of SLOs, the sialylation status of prions changes by host STs. We propose that this mechanism is responsible for camouflaging prions in SLOs and has broad implications.

CORR Insights(®): oxidized zirconium head on crosslinked polyethylene liner in total hip arthroplasty: a 7- to 12-year in vivo comparative wear study.

Where Are We Now? Hip surgeons and material scientists agree that while reducing bearing-surface wear after THA is important, the real goals are to prevent osteolysis and aseptic loosening. Most hip replacements are performed using highly crosslinked polyethylene (XLPE) liners, since many surgeons are concerned about problems associated with ceramic-on-ceramic and metal-on-metal (MoM) bearings, including squeaking and ceramic fractures for the former [1], and elevated serum ion levels from (MoM) couplings with the latter [6]. However, although a metaanalysis of randomized trials confirmed that XLPE decreased linear and volumetric wear rates [11], it remains unclear whether XLPE actually reduces the likelihood of aseptic loosening after THA [10]. Recommended as an alternative bearing surface, oxidized zirconium was developed to reduce the wear rates of cobalt-chrome heads against polyethylene bearings. The linear wear rate for oxidized zirconium with XLPE liners has been shown to be 4 μm/year [4]. However, in a 5-year followup of a randomized controlled trial, no difference in wear rates was noted between cobalt-chrome and oxidized zirconium heads with XLPE [9]. Crosslinked polyethylene liners seem to make a larger difference in wear than does the head surface against which the polyethylene is placed. Where Do We Need To Go? With the number of primary and revision THAs rising, it is crucial that we produce reliable implants with excellent long-term durability and biocompatability. Further study on the long-term data associated with oxidized zirconium on XLPE bearings is warranted. In their paper, Karidakis and colleagues report lower wear rates of oxidized zirconium heads on XLPE liners when compared to ceramic heads. We need solid long-term data reflecting not only the survival of the implant and the wear rates of bearing surfaces, but also the effects of the wear debris on our patients’ bodies. Because some reports have found that XLPE liners produce wear particles in the submicron range, which can be phagocytosed by human monocytes and so may over longer time periods yet result in osteolysis [12, 14], longer-term studies are needed. The production of rather round shaped submicron wear particles by XLPE liners is a concern that has not been adequately adressed by in vivo studies. Phagocytosed wear particles have the capability to get to the liver, spleen, and other organs [13]. As orthopaedic surgeons, we often rely on radiographs to follow our patients; while perhaps adequate to identify major problems like wear or loosening, I believe we have to do a better job of considering the impact of orthopaedic implants on the whole patient, and not just the hip. We need to learn more about the systemic effects of the arthroplasties we perform. How Do We Get There? To get these answers, we need carefully conducted, long-term clinical followup studies that evaluate THA bearings. Digitized radiographs with computer-aided wear analysis or radiostereometry [5, 10] can provide us with data about the rate of wear at the hip, but as I have suggested here, we need to begin to answer some larger questions about corrosion products and wear debris created by THAs in vivo. Ideally, future investigations will develop methods that can properly identify the fate of these wear particles. Autopsies of patients with THA could provide us with sections of liver, spleen, and other organs. Previous studies [2, 3, 13] have shown mostly metal but also ultrahigh molecular weight polyethylene particle dissemination to those organs. The detected polyethylene particles were in the submicron range. The increased production of such wear particles by XLPE calls for more and larger postmortem studies in order to rule out accumulation of wear debris in parenchymatous and lymphoreticular tissues. Flow cytometry could be a tool to identify monocytes loaded with polyethylene particles in vivo. Laser-scanning microscopy could potentially identify human monocytes containing wear particles. Wear debris from orthopaedic implants is present in lymphoreticular tissue. An increase in wear particle load of human monocytes could reduce the capacity of the immune system. Therefore, we must check the immune system for activity of interleukins, interferone, and tumor necrosis factor, as XLPE wear particles have been shown to induce an increased inflammatory response in vitro [7, 8]. We still have a great deal to learn about the wear particles generated by oxidized zirconium heads on XLPE liners, both at the local and systemic levels.

In utero transmission and tissue distribution of chronic wasting disease-associated prions in free-ranging Rocky Mountain elk.

The presence of disease-associated prions in tissues and bodily fluids of chronic wasting disease (CWD)-infected cervids has received much investigation, yet little is known about mother-to-offspring transmission of CWD. Our previous work demonstrated that mother-to-offspring transmission is efficient in an experimental setting. To address the question of relevance in a naturally exposed free-ranging population, we assessed maternal and fetal tissues derived from 19 elk dam-calf pairs collected from free-ranging Rocky Mountain elk from north-central Colorado, a known CWD endemic region. Conventional immunohistochemistry identified three of 19 CWD-positive dams, whereas a more sensitive assay [serial protein misfolding cyclic amplification (sPMCA)] detected CWD prion seeding activity (PrPCWD) in 15 of 19 dams. PrPCWD distribution in tissues was widespread, and included the central nervous system (CNS), lymphoreticular system, and reproductive, secretory, excretory and adipose tissues. Interestingly, five of 15 sPMCA-positive dams showed no evidence of PrPCWD in either CNS or lymphoreticular system, sites typically assessed in diagnosing CWD. Analysis of fetal tissues harvested from the 15 sPMCA-positive dams revealed PrPCWD in 80 % of fetuses (12 of 15), regardless of gestational stage. These findings demonstrated that PrPCWD is more abundant in peripheral tissues of CWD-exposed elk than current diagnostic methods suggest, and that transmission of prions from mother to offspring may contribute to the efficient transmission of CWD in naturally exposed cervid populations.

The Cellular Prion Protein: A Player in Immunological Quiescence.

Despite intensive studies since the 1990s, the physiological role of the cellular prion protein (PrPC) remains elusive. Here, we present a novel concept suggesting that PrPC contributes to immunological quiescence in addition to cell protection. PrPC is highly expressed in diverse organs that by multiple means are particularly protected from inflammation, such as the brain, eye, placenta, pregnant uterus, and testes, while at the same time it is expressed in most cells of the lymphoreticular system. In this paradigm, PrPC serves two principal roles: to modulate the inflammatory potential of immune cells and to protect vulnerable parenchymal cells against noxious insults generated through inflammation. Here, we review studies of PrPC physiology in view of this concept.

Um caso clínico de linfoma de células do manto

Introduction: The non-Hodgkin's lymphomas are a diverse group of neoplasms of the lymphoreticular system. The diagnosis is often difficult. In this case report we present a rare type of lymphoma, with a rare form of presentation, in which the family doctor had an important role to play in collating clinical information to make the diagnosis. Case report: A 73-year-old man initially presented with supraorbital swelling and a complaint of pressure in the eye, without other symptoms. An ophthalmologist evaluated the patient and considered that the swelling arose from adipose tissue. After worsening of the orbital swelling and the appearance of swelling of the lips and cervical adenopathy, a lymphoproliferative disease was suspected. The patient was sent for an internal medicine consultation and the diagnosis of mantle cell lymphoma was made after excisional biopsy of a lymph node. Comment: This case shows some of the difficulty encountered in diagnosing a non-Hodgkin's lymphoma, given great variability in their presentations. Close follow-up of the patient during numerous consultations was essential to make the diagnosis of a lymphoproliferative disease.

Haemodynamic Monitoring of Pericardial Effusion with Cardiac Tamponade in a Patient with Colorectal Cancer

Metastatic cardiac malignancies mainly come from breast, lung, esophagus and lymphoreticular system. Metastasis from colorectal cancer to the heart or pericardium is seldom reported and only sporadic antemortem cases have been reported. We report an unusual case of malignant pericardial effusion with cardiac tamponade caused by metastatic adenocarcinoma of colon in a 58 year old patient and haemodynamic monitoring with lithium dilution cardiac output (LiDCO) method of measuring cardiac output due to prepare patient for surgery of subileus.

Foodborne-Transmitted Prions From the Brain of Cows With Bovine Spongiform Encephalopathy Ascend in Afferent Neurons to the Simian Central Nervous System and Spread to Tonsils and Spleen at a Late Stage of the Incubation Period.

Protease-resistant prion protein (PrP(res)) accumulation in lymphoreticular tissues indicates prion infection. To date, tonsillectomy and appendectomy samples have been used in population prevalence surveys to detect clinically silent carriers of variant Creutzfeldt-Jakob disease (vCJD). However, the temporal sequence of prion spread in the human body is still not known. We therefore traced the temporal-spatial pattern of PrP(res) accumulation in the body of a simian vCJD model. Cynomolgus monkeys were fed brain of (eleven) cows with bovine spongiform encephalopathy, and some were euthanized before and some after onset of neurological signs. PrP(res) was detected in tissues by a paraffin-embedded tissue blot technique and a semiquantitative Western immunoblot assay. Bovine spongiform encephalopathy (BSE)-associated prions were preferentially transported from the gut to the central nervous system (CNS) along sensory nerve fibers and initially entered the simian CNS at lumbar spinal cord levels. In asymptomatic animals, we found BSE in 50% and 12% of gut- and tonsil-derived samples, respectively. Unlike in rodents and ruminants, foodborne BSE-associated prions entered the simian CNS via afferent neurons. From sites of initial CNS invasion, prions spread centrifugally to tonsils and spleen at an advanced stage of the incubation period, thus explaining why tonsil specimens were not reliable for detection of simian disease carriers before onset of clinical signs.

Nasal associated lymphoid tissue of the Syrian golden hamster expresses high levels of PrPC.

The key event in the pathogenesis of the transmissible spongiform encephalopathies is a template-dependent misfolding event where an infectious isoform of the prion protein (PrPSc) comes into contact with native prion protein (PrPC) and changes its conformation to PrPSc. In many extraneurally inoculated models of prion disease this PrPC misfolding event occurs in lymphoid tissues prior to neuroinvasion. The primary objective of this study was to compare levels of total PrPC in hamster lymphoid tissues involved in the early pathogenesis of prion disease. Lymphoid tissues were collected from golden Syrian hamsters and Western blot analysis was performed to quantify PrPC levels. PrPC immunohistochemistry (IHC) of paraffin embedded tissue sections was performed to identify PrPC distribution in tissues of the lymphoreticular system. Nasal associated lymphoid tissue contained the highest amount of total PrPC followed by Peyer’s patches, mesenteric and submandibular lymph nodes, and spleen. The relative levels of PrPC expression in IHC processed tissue correlated strongly with the Western blot data, with high levels of PrPC corresponding with a higher percentage of PrPC positive B cell follicles. High levels of PrPC in lymphoid tissues closely associated with the nasal cavity could contribute to the relative increased efficiency of the nasal route of entry of prions, compared to other routes of infection.

Reticuloendothelial malignancy of head and neck: A comprehensive review.

The mononuclear phagocyte system consists of cells that have a common lineage whose primary function is phagocytosis. The specific immunity is achieved by the combined effects of macrophages and lymphocytes, and system has been called lymphoreticular system. Reticuloendothelial system means a special group of cells, scattered in different parts of the body, but all having some common characteristics. These cells are powerful phagocytes.

Influence of Breed and Genotype on the Onset and Distribution of Infectivity and Disease-associated Prion Protein in Sheep Following Oral Infection with the Bovine Spongiform Encephalopathy Agent

The onset and distribution of infectivity and disease-specific prion protein (PrP(d)) accumulation was studied in Romney and Suffolk sheep of the ARQ/ARQ, ARQ/ARR and ARR/ARR prion protein gene (Prnp) genotypes (where A stands for alanine, R for arginine and Q for glutamine at codons 136, 154 and 171 of PrP), following experimental oral infection with cattle-derived bovine spongiform encephalopathy (BSE) agent. Groups of sheep were killed at regular intervals and a wide range of tissues taken for mouse bioassay or immunohistochemistry (IHC), or both. Bioassay results for infectivity were mostly coincident with those of PrP(d) detection by IHC both in terms of tissues and time post infection. Neither PrP(d) nor infectivity was detected in any tissues of BSE-dosed ARQ/ARR or ARR/ARR sheep or of undosed controls. Moreover, four ARQ/ARQ Suffolk sheep, which were methionine (M)/threonine heterozygous at codon 112 of the Prnp gene, did not show any biological or immunohistochemical evidence of infection, while those homozygous for methionine (MARQ/MARQ) did. In MARQ/MARQ sheep of both breeds, initial PrP(d) accumulation was identified in lymphoreticular system (LRS) tissues followed by the central nervous system (CNS) and enteric nervous system (ENS) and finally by the autonomic nervous system and peripheral nervous system and other organs. Detection of infectivity closely mimicked this sequence. No PrP(d) was observed in the ENS prior to its accumulation in the CNS, suggesting that ENS involvement occurred simultaneously to that of, or followed centrifugal spread from, the CNS. The distribution of PrP(d) within the ENS further suggested a progressive spread from the ileal plexus to other ENS segments via neuronal connections of the gut wall. Differences between the two breeds were noted in terms of involvement of LRS and ENS tissues, with Romney sheep showing a more delayed and less consistent PrP(d) accumulation than Suffolk sheep in such tissues. Whether this accounted for the slight delay (∼5 months) in the appearance of clinical signs in Romney sheep is debatable since by the last scheduled kill before animals reached clinical end point, both breeds showed widespread accumulation and similar magnitudes of PrP(d) accumulation in the brain.

English

Non-Hodgkin's Lymphoma (NHL) is a group of neoplasms that originate from the cells of the lymphoreticular system. Forty percent of Non-Hodgkin's lymphoma arises from extranodal sites. Common primary extranodal sites of lymphomas include stomach, liver, soft tissue, dura, bone, intestine and bone marrow. Primary non-Hodgkin's lymphoma of the nose and paranasal sinus is rare. We report a case of a young 22 years aged man who came to us with symptoms of nasal obstruction and swelling over right side of face with subsequent development of neck swelling. We diagnosed the lymphoma by biopsy and FNAC of the submandibular lymph node. This case highlights the importance of making a full visual inspection of the involved sinus in order to avoid missing an The etiology is unknown but it is thought to be due to virus and immunosuppression. Primary non-Hodgkin lymphomas (NHLs) of the sinonasal tract comprise a rare entity that constitutes 1.5% of all NHLs and 2.2% of extranodal lymphomas. Clinical diagnosis may be very challenging because of the variety and low specificity of the presenting symptoms and signs. In this article, we report a case of lymphoma that was diagnosed after we used an endoscopic procedure.

Mycosis fungoides – case presentation

Sir, Mycosis fungoides (MF) is a neoplastic disease of the lymphoreticular system with substrate of T lymphocyte hyperplasia and multifactorial etiology. Usual onset is around age 50, with skin lesions, and in advanced stages affects the internal organs. Mycosis fungoides has specific histological feature: polymorphous infiltrate located in the papillary dermis which ends abruptly in the middle dermis.

Invasive Fungal Sinusitis in Neutropenic Patients: A Case Report and Literature Review

Introduction: Acute invasive fungal rhinosinusitis is uncommon, potentially lethal, being opportunistic infection seen mainly in diabetics and immunocompromised individuals. It is one form of infection that appears to be increasing in frequency? The classification is based on the immunological relationship between fungus and host and existing invasive and noninvasive forms. Acute fulminant fungal sinusitis is usually found in neutropenic patients with cancer of lymphoreticular or hematopoietic systems and has invasion of blood vessels character. In this group, aspergillosis is responsible for more than 80% of infections, especially Aspergillus fumigatus. The treatment is surgery with wide debridement, systemic antifungal drugs, and correction of underlying metabolic or immunologic disorders.

Immunohistochemical expression of MMP1 and TIMP1 as markers of migration in Hodgkin’s and non-Hodgkin’s lymphoma of the head and neck region (A comparative study)

Background: Malignant lymphoma is a term that describes primary tumors of the lymphoreticular system, almost all of which arise from lymphocytes.MMP-1 is the most ubiquitously expressed interstitial collagenase, a subfamily of MMPs that cleaves stromal collagens. It is also called collagenase-1.TIMPs which inhibits MMP activity and thereby restrict extracellular matrix breakdown, TIMP-1 is a stromal factor that has a wide spectrum of functions in different tissues. Material and Methods: This study was performed on (68) formalin-fixed, paraffin-embedded blocks, histopathologically diagnosed as lymphoma (head and neck lesions). Immunohistochemical staining of MMP1and TIMP1 was performed on each case of the study sample. Results: The expression of MMP1was cytoplasmic, the study cases showed a 98.5% positive reaction to MMP1, score 3 was the most common and found in 60.3% of all cases.The expression of TIMP1was cytoplasmic, 92.6% of cases expressed positive reactions to TIMP1, score 1 was the most common and found in 57.4% of all cases. Conclusion: This study showed for the first time the effect of MMP-1 in HL, which is considered to be as an invasive and migratory cell marker. A significant difference was found among the subtypes of NHL in relation to TIMP1, TIMP1inhibits the effect of MMP1 and as MMP1 is elevated the TIMP1 will be elevated too.

Allelic variants at codon 146 in the PRNP gene show significant differences in the risk for natural scrapie in Cypriot goats.

Previous studies have shown the association between the polymorphisms serine (S) or aspartic acid (D) at codon 146 of the PRNP gene and resistance to scrapie. All goats aged >12 months (a total of 1075 animals) from four herds with the highest prevalence of scrapie in the country were culled and tested, of which 234 (21·7%) were positive by either the rapid test or immunohistochemistry (IHC) for any of the tissues tested. The odds of scrapie infection occurring in NN146 goats was 101 [95% credible interval (CrI) 19-2938] times higher than for non-NN146 or unknown genotypes. IHC applied to lymphoreticular tissue produced the highest sensitivity (94%, 95% CrI 90-97). The presence of putatively resistant non-NN146 alleles in the Cypriot goat population, severely affected by scrapie, provides a potential tool to reduce/eradicate scrapie provided that coordinated nationwide breeding programmes are implemented and maintained over time.

Distribution of peripheral PrP(Sc) in sheep with naturally acquired scrapie.

Accumulation of prion protein (PrPSc) in the central nervous system is the hallmark of transmissible spongiform encephalopathies. However, in some of these diseases such as scrapie or chronic wasting disease, the PrPSc can also accumulate in other tissues, particularly in the lymphoreticular system. In recent years, PrPSc in organs other than nervous and lymphoid have been described, suggesting that distribution of this protein in affected individuals may be much larger than previously thought. In the present study, 11 non-nervous/non-lymphoid organs from 16 naturally scrapie infected sheep in advanced stages of the disease were examined for the presence of PrPSc. Fourteen infected sheep were of the ARQ/ARQ PRNP genotype and 2 of the VRQ/VRQ, where the letters A, R, Q, and V represent the codes for amino-acids alanine, arginine, glutamine and valine, respectively. Adrenal gland, pancreas, heart, skin, urinary bladder and mammary gland were positive for PrPSc by immunohistochemistry and IDEXX HerdChek scrapie/BSE Antigen EIA Test in at least one animal. Lung, liver, kidney and skeletal muscle exhibited PrPSc deposits by immunohistochemistry only. To our knowledge, this is the first report regarding the presence of PrPSc in the heart, pancreas and urinary bladder in naturally acquired scrapie infections. In some other organs examined, in which PrPSc had been previously detected, PrPSc immunolabeling was observed to be associated with new structures within those organs. The results of the present study illustrate a wide dissemination of PrPSc in both ARQ/ARQ and VRQ/VRQ infected sheep, even when the involvement of the lymphoreticular system is scarce or absent, thus highlighting the role of the peripheral nervous system in the spread of PrPSc.

Hemophagocytic lymphohistiocytosis syndrome in Dengue hemorrhagic fever.

Hemophagocytic lymphohistiocytosis (HLH) is a life threatening florid activation of macrophages of the lymphoreticular system. It is reported to be associated with dengue in children in India and carries a high mortality. Patients present with high fever, worsening blood cell counts, splenomegaly, abnormal liver enzymes with features of liver failure, coagulopathy and neurological complications. The diagnosis is according to "Diagnostic Guidelines for HLH 2004", based on a triad of clinical, blood parameters and bone marrow cytology. In the present study, data of 212 children admitted with dengue were analyzed. Of 212 children, 31 children were classified as suspect HLH and advised bone marrow evaluation; of whom 23 children had marrow evidence of HLH. Worsening of blood cell counts were recorded in all children with a mean platelet count of 58,303.03 cells/cumm, low hematocrit in 95.65%, low mean hemoglobin level of 8.37g/dL, high erythrocyte sedimentation rate (ESR) and prolonged pro-thrombin time/international normalization ratio (PT/INR). Serum triglycerides, ferritin and transaminases were high. Of the 23 children, 19 patients received intravenous immunoglobulin (IVIG) and all of these children recovered. Dengue with multi-organ dysfunction is commonly concurrent to HLH in the marrow and hence, an early diagnosis based on clinical, laboratory and bone marrow evaluation is significant. A bone marrow evaluation confirms the diagnosis of HLH.

Characterization of intratumor magnetic nanoparticle distribution and heating in a rat model of metastatic spine disease

The goal of this study was to optimize local delivery of magnetic nanoparticles in a rat model of metastatic breast cancer in the spine for tumor hyperthermia while minimizing systemic exposure. A syngeneic mammary adenocarcinoma was implanted into the L-6 vertebral body of 69 female Fischer rats. Suspensions of 100-nm starch-coated iron oxide magnetic nanoparticles (micromod Partikeltechnologie GmbH) were injected into tumors 9 or 13 days after implantation. For nanoparticle distribution studies, tissues were harvested from a cohort of 36 rats, and inductively coupled plasma mass spectrometry and histopathological studies with Prussian blue staining were used to analyze the samples. Intratumor heating was tested in 4 anesthetized animals with a 20-minute exposure to an alternating magnetic field (AMF) at a frequency of 150 kHz and an amplitude of 48 kA/m or 63.3 kA/m. Intratumor and rectal temperatures were measured, and functional assessments of AMF-exposed animals and histopathological studies of heated tumor samples were examined. Rectal temperatures alone were tested in a cohort of 29 rats during AMF exposure with or without nanoparticle administration. Animal studies were completed in accordance with the protocols of the University Animal Care and Use Committee. Nanoparticles remained within the tumor mass within 3 hours of injection and migrated into the bone at 6, 12, and 24 hours. Subarachnoid accumulation of nanoparticles was noted at 48 hours. No evidence of lymphoreticular nanoparticle exposure was found on histological investigation or via inductively coupled plasma mass spectrometry. The mean intratumor temperatures were 43.2°C and 40.6°C on exposure to 63.3 kA/m and 48 kA/m, respectively, with histological evidence of necrosis. All animals were ambulatory at 24 hours after treatment with no evidence of neurological dysfunction. Locally delivered magnetic nanoparticles activated by an AMF can generate hyperthermia in spinal tumors without accumulating in the lymphoreticular system and without damaging the spinal cord, thereby limiting neurological dysfunction and minimizing systemic exposure. Magnetic nanoparticle hyperthermia may be a viable option for palliative therapy of spinal tumors.