Unprocessed Atmospheric Nitrate in Waters of the Northern Forest Region in the U.S. and Canada.

Little is known about the regional extent and variability of nitrate from atmospheric deposition that is transported to streams without biological processing in forests. We measured water chemistry and isotopic tracers (δ18O and δ15N) of nitrate sources across the Northern Forest Region of the U.S. and Canada and reanalyzed data from other studies to determine when, where, and how unprocessed atmospheric nitrate was transported in catchments. These inputs were more widespread and numerous than commonly recognized, but with high spatial and temporal variability. Only 6 of 32 streams had high fractions (>20%) of unprocessed atmospheric nitrate during baseflow. Seventeen had high fractions during stormflow or snowmelt, which corresponded to large fractions in near-surface soil waters or groundwaters, but not deep groundwater. The remaining 10 streams occasionally had some (<20%) unprocessed atmospheric nitrate during stormflow or baseflow. Large, sporadic events may continue to be cryptic due to atmospheric deposition variation among storms and a near complete lack of monitoring for these events. A general lack of observance may bias perceptions of occurrence; sustained monitoring of chronic nitrogen pollution effects on forests with nitrate source apportionments may offer insights needed to advance the science as well as assess regulatory and management schemes.

Estimating open population site occupancy from presence-absence data lacking the robust design.

Many animal monitoring studies seek to estimate the proportion of a study area occupied by a target population. The study area is divided into spatially distinct sites where the detected presence or absence of the population is recorded, and this is repeated in time for multiple seasons. However, when occupied sites are detected with probability p < 1, the lack of a detection does not imply lack of occupancy. MacKenzie et al. (2003, Ecology 84, 2200-2207) developed a multiseason model for estimating seasonal site occupancy (ψt ) while accounting for unknown p. Their model performs well when observations are collected according to the robust design, where multiple sampling occasions occur during each season; the repeated sampling aids in the estimation p. However, their model does not perform as well when the robust design is lacking. In this paper, we propose an alternative likelihood model that yields improved seasonal estimates of p and Ψt in the absence of the robust design. We construct the marginal likelihood of the observed data by conditioning on, and summing out, the latent number of occupied sites during each season. A simulation study shows that in cases without the robust design, the proposed model estimates p with less bias than the MacKenzie et al. model and hence improves the estimates of Ψt . We apply both models to a data set consisting of repeated presence-absence observations of American robins (Turdus migratorius) with yearly survey periods. The two models are compared to a third estimator available when the repeated counts (from the same study) are considered, with the proposed model yielding estimates of Ψt closest to estimates from the point count model.

Sinks for nitrogen inputs in terrestrial ecosystems: a meta-analysis of 15N tracer field studies.

Effects of anthropogenic nitrogen (N) deposition and the ability of terrestrial ecosystems to store carbon (C) depend in part on the amount of N retained in the system and its partitioning among plant and soil pools. We conducted a meta-analysis of studies at 48 sites across four continents that used enriched 15N isotope tracers in order to synthesize information about total ecosystem N retention (i.e., total ecosystem 15N recovery in plant and soil pools) across natural systems and N partitioning among ecosystem pools. The greatest recoveries of ecosystem 15N tracer occurred in shrublands (mean, 89.5%) and wetlands (84.8%) followed by forests (74.9%) and grasslands (51.8%). In the short term (< 1 week after 15N tracer application), total ecosystem 15N recovery was negatively correlated with fine-root and soil 15N natural abundance, and organic soil C and N concentration but was positively correlated with mean annual temperature and mineral soil C:N. In the longer term (3-18 months after 15N tracer application), total ecosystem 15N retention was negatively correlated with foliar natural-abundance 15N but was positively correlated with mineral soil C and N concentration and C:N, showing that plant and soil natural-abundance 15N and soil C:N are good indicators of total ecosystem N retention. Foliar N concentration was not significantly related to ecosystem 15N tracer recovery, suggesting that plant N status is not a good predictor of total ecosystem N retention. Because the largest ecosystem sinks for 15N tracer were below ground in forests, shrublands, and grasslands, we conclude that growth enhancement and potential for increased C storage in aboveground biomass from atmospheric N deposition is likely to be modest in these ecosystems. Total ecosystem 15N recovery decreased with N fertilization, with an apparent threshold fertilization rate of 46 kg N x ha(-1) x yr(-1) above which most ecosystems showed net losses of applied 15N tracer in response to N fertilizer addition.

Mercury distribution across 14 U.S. Forests. Part I: spatial patterns of concentrations in biomass, litter, and soils.

Results from a systematic investigation of mercury (Hg) concentrations across 14 forest sites in the United States show highest concentrations in litter layers, strongly enriched in Hg compared to aboveground tissues and indicative of substantial postdepositional sorption of Hg. Soil Hg concentrations were lower than in litter, with highest concentrations in surface soils. Aboveground tissues showed no detectable spatial patterns, likely due to 17 different tree species present across sites. Litter and soil Hg concentrations positively correlated with carbon (C), latitude, precipitation, and clay (in soil), which together explained up to 94% of concentration variability. We observed strong latitudinal increases in Hg in soils and litter, in contrast to inverse latitudinal gradients of atmospheric deposition measures. Soil and litter Hg concentrations were closely linked to C contents, consistent with well-known associations between organic matter and Hg, and we propose that C also shapes distribution of Hg in forests at continental scales. The consistent link between C and Hg distribution may reflect a long-term legacy whereby old, C-rich soil and litter layers sequester atmospheric Hg depositions over long time periods. Based on a multiregression model, we present a distribution map of Hg concentrations in surface soils of the United States.

Models for estimating abundance from repeated counts of an open metapopulation.

Using only spatially and temporally replicated point counts, Royle (2004b, Biometrics 60, 108-115) developed an N-mixture model to estimate the abundance of an animal population when individual animal detection probability is unknown. One assumption inherent in this model is that the animal populations at each sampled location are closed with respect to migration, births, and deaths throughout the study. In the past this has been verified solely by biological arguments related to the study design as no statistical verification was available. In this article, we propose a generalization of the N-mixture model that can be used to formally test the closure assumption. Additionally, when applied to an open metapopulation, the generalized model provides estimates of population dynamics parameters and yields abundance estimates that account for imperfect detection probability and do not require the closure assumption. A simulation study shows these abundance estimates are less biased than the abundance estimate obtained from the original N-mixture model. The proposed model is then applied to two data sets of avian point counts. The first example demonstrates the closure test on a single-season study of Mallards (Anas platyrhynchos), and the second uses the proposed model to estimate the population dynamics parameters and yearly abundance of American robins (Turdus migratorius) from a multi-year study.

Estimating parameters of a forest ecosystem C model with measurements of stocks and fluxes as joint constraints.

We conducted an inverse modeling analysis, using a variety of data streams (tower-based eddy covariance measurements of net ecosystem exchange, NEE, of CO2, chamber-based measurements of soil respiration, and ancillary ecological measurements of leaf area index, litterfall, and woody biomass increment) to estimate parameters and initial carbon (C) stocks of a simple forest C-cycle model, DALEC, using Monte Carlo procedures. Our study site is the spruce-dominated Howland Forest AmeriFlux site, in central Maine, USA. Our analysis focuses on: (1) full characterization of data uncertainties, and treatment of these uncertainties in the parameter estimation; (2) evaluation of how combinations of different data streams influence posterior parameter distributions and model uncertainties; and (3) comparison of model performance (in terms of both predicted fluxes and pool dynamics) during a 4-year calibration period (1997-2000) and a 4-year validation period ("forward run", 2001-2004). We find that woody biomass increment, and, to a lesser degree, soil respiration, measurements contribute to marked reductions in uncertainties in parameter estimates and model predictions as these provide orthogonal constraints to the tower NEE measurements. However, none of the data are effective at constraining fine root or soil C pool dynamics, suggesting that these should be targets for future measurement efforts. A key finding is that adding additional constraints not only reduces uncertainties (i.e., narrower confidence intervals) on model predictions, but at the same time also results in improved model predictions by greatly reducing bias associated with predictions during the forward run.

Biogeochemical response of a northeastern forest ecosystem to biosolids amendments.

In the northeastern United States interest in the use of biosolids on forest lands is growing due to the prevalence of extensive forests and market incentives for waste disposal, yet much of the regulatory framework for biosolids land application is based on agronomic practice. This study evaluated the response of soils in a young ( approximately 20 yr old) deciduous forest to lime-stabilized biosolids amendments focusing on (i) the temporal and spatial evolution of the pH response, (ii) soil exchangeable cation response, (iii) the risk of trace metal accumulations, and (iv) a bioindicator of treatments (i.e., foliar chemistry). Eighteen plots were established in two study phases with lime-stabilized biosolids loading targets of 0 (control), 4.5, 6.7, 13.4, 20.2, 26.9, and 33.6 Mg (megagram) calcium carbonate equivalents (CCE) ha(-1), with the lowest target rate of addition representing the current regulated loading limit for forest biosolids applications in Maine. The pH of the O horizon increased immediately >2 pH units, and then declined with time, while B horizon pH increased gradually, taking over 1 yr to achieve approximately 1.0 pH unit increase at the highest loading target. O-horizon exchangeable Ca concentration increases dominated soil chemical change and resulted in decreases in exchangeable H and Al. Few significant increases in soil trace metal concentrations had occurred at any soil depth after 1 yr of treatment. Foliar response generally reflected changes in soil chemistry, with Ca concentration increases most significant. This research provides critical insights on forest soil response to application of lime-stabilized biosolids and suggests opportunities for higher loading targets in forests should be examined.

Influence of spring phenology on seasonal and annual carbon balance in two contrasting New England forests.

Spring phenology is thought to exert a major influence on the carbon (C) balance of temperate and boreal ecosystems. We investigated this hypothesis using four spring onset phenological indicators in conjunction with surface-atmosphere CO(2) exchange data from the conifer-dominated Howland Forest and deciduous-dominated Harvard Forest AmeriFlux sites. All phenological measures, including CO(2) source-sink transition dates, could be well predicted on the basis of a simple two-parameter spring warming model, indicating good potential for improving the representation of phenological transitions and their dynamic responsiveness to climate variability in land surface models. The date at which canopy-scale photosynthetic capacity reached a threshold value of 12 micromol m(-2) s(-1) was better correlated with spring and annual flux integrals than were either deciduous or coniferous bud burst dates. For all phenological indicators, earlier spring onset consistently, but not always significantly, resulted in higher gross primary productivity (GPP) and ecosystem respiration (RE) for both seasonal (spring months, April-June) and annual flux integrals. The increase in RE was less than that in GPP; depending on the phenological indicator used, a one-day advance in spring onset increased springtime net ecosystem productivity (NEP) by 2-4 g C m(-2) day(-1). In general, we could not detect significant differences between the two forest types in response to earlier spring, although the response to earlier spring was generally more pronounced for Harvard Forest than for Howland Forest, suggesting that future climate warming may favor deciduous species over coniferous species, at least in this region. The effect of earlier spring tended to be about twice as large when annual rather than springtime flux integrals were considered. This result is suggestive of both immediate and lagged effects of earlier spring onset on ecosystem C cycling, perhaps as a result of accelerated N cycling rates and cascading effects on N uptake, foliar N concentrations and photosynthetic capacity.

Influence of decomposition on chemical properties of plant- and manure-derived dissolved organic matter and sorption to goethite.

Sorption of dissolved organic matter (DOM) plays an important role in maintaining the fertility and quality of soils in agricultural ecosystems. Few studies have examined the effects of decomposition on DOM sorption and chemical characteristics. This study investigated the sorption to goethite (alpha-FeOOH) of fresh and decomposed hydrophilic (HPL) and hydrophobic (HPB) DOM fractions extracted from the shoots and roots of crimson clover (Trifolium incarnatum L.), corn (Zea mays L.), soybean [Glycine max (L.) Merr.], hairy vetch (Vicia villosa L.), and dairy and poultry manures. Sorption was positively related to apparent molecular weight (MWAP), aromaticity as measured by absorptivity at 280 nm, and phenolic acid content. A 10-d laboratory microbial decomposition of the source organic matter generally increased the sorption of the extracted DOM onto goethite. The decomposition effect on sorption was greater for the HPL fractions than for the HPB fractions. There was a decrease in the MWAP values of the DOM samples following sorption to goethite. In many cases the reduction in MWAP was large, indicating a strong preference by goethite for the higher MWAP DOM fractions. The results of this laboratory-based research demonstrate that microbial processes affect the chemical characteristics of DOM which may affect the distribution of soil organic C pools.

Humoral immune response associated with lyme borreliosis in nonhuman primates: analysis by immunoblotting and enzyme-linked immunosorbent assay with sonicates or recombinant proteins.

The immune response to Borrelia burgdorferi, the causative agent of Lyme disease, is complex. We studied the immunoglobulin M (IgM) and IgG antibody response to N40Br, a sensu stricto strain, in the rhesus macaque(nonhuman primate [NHP]) model of infection to identify the spirochetal protein targets of specific antibody. Antigens used in enzyme-linked immunosorbent assays were whole-cell sonicates of the spirochete and recombinant proteins of B. burgdorferi. Immunoblotting with a commercially available strip and subsequent quantitative densitometry of the bands were also used. Sera from four different groups of NHPs were used: immunocompetent, transiently immunosuppressed, extended immunosuppressed, and uninfected. In immunocompetent and transiently immunosuppressed NHPs, there was a strong IgM and IgG response. Major proteins for the early IgM response were P39 and P41 and recombinant BmpA and OspC. Major proteins for the later IgG response were P39, P41, P18, P60, P66, and recombinant BmpA and DbpA. There was no significant response in the NHPs to recombinant OspA or to Arp, a 37-kDa protein that elicits an antibody response during infection in mice. Most antibody responses, except for that to DbpA, were markedly diminished by prolonged dexamethasone treatment. This study supports the hypothesis that recombinant proteins may provide a useful adjunct to current diagnostic testing for Lyme borreliosis.

Central and peripheral nervous system infection, immunity, and inflammation in the NHP model of Lyme borreliosis.

The relationship between chronic infection, antispirochetal immunity, and inflammation is unknown in Lyme neuroborreliosis. In the nonhuman primate model of Lyme neuroborreliosis, we measured spirochetal density in the nervous system and other tissues by polymerase chain reaction and correlated these values to anti-Borrelia burgdorferi antibody in the serum and cerebrospinal fluid, and to inflammation in tissues. Despite substantial presence of Borrelia burgdorferi, the causative agent of Lyme borreliosis, in the central nervous system, only minor inflammation was present there, though skeletal and cardiac muscle, which contained similar levels of spirochete, were highly inflamed. Anti-Borrelia burgdoferi antibody was present in the cerebrospinal fluid but was not selectively concentrated. All infected animals developed anti-Borrelia burgdorferi antibody in the serum, but increased amplitude of antibody was not predictive of higher levels of infection. These data demonstrate that Lyme neuroborreliosis is a persistent infection, that spirochetal presence is a necessary but not sufficient condition for inflammation, and that antibody measured in serum may not predict the severity of infection.

Neoplasms of the ampulla of vater with concurrent pancreatic intraductal neoplasia: a histological and molecular study.

Adenoma and adenocarcinoma of the ampulla of Vater are uncommon neoplasms of the gastrointestinal tract. Only one report has analyzed the relationship between ampullary adenocarcinoma and pancreatic intraductal neoplasia (PanIN), the precursor lesion of pancreatic adenocarcinoma. An association between PanIN and ampullary adenoma has not been reported previously. Case reports have documented the progression of PanIN to invasive pancreatic adenocarcinoma. We reviewed five resected ampullary adenoma and 17 ampullary adenocarcinoma cases and evaluated the pancreas for PanIN. Pancreatic sections from 35 autopsies were reviewed as a control group. Immunohistochemistry for overexpression of p53 and COX-2 proteins was performed in selected cases, as was PCR analysis for K-ras mutations. Follow-up clinical data were obtained. All 22 ampullary neoplasms were associated with PanIN, which was high grade in two (40%) adenoma cases and seven (41%) adenocarcinoma cases. In 16 (73%) evaluable cases, PanIN extended to the pancreatic resection margin; two of which had high grade PanIN. Among the autopsy controls eight (23%) had low-grade PanIN. Seven of the 22 ampullary cases but none of the autopsy controls had coexistent pancreatitis. A smoking history was present in two of four autopsy cases in which this history was available. Overexpression of the p53 and COX-2 proteins was present in only one case of high-grade PanIN. K-ras mutations were present in four of four of the PanIN lesions evaluated, including one autopsy case. Clinical follow-up revealed no progression of PanIN to invasive carcinoma in the remnant pancreas, although the follow-up period was too short to adequately assess that risk (an average of 3.8 y for adenoma cases and 2.5 y for adenocarcinoma cases). We conclude that adenomas and carcinomas of the ampulla are associated with PanIN, and often high-grade PanIN. Although its malignant potential has not been fully established, PanIN is underreported and often unrecognized. PanIN may be analogous to colorectal adenoma in that both are prevalent in the older adult population, but few progress to carcinoma.

Thyroid transcription factor-1: immunohistochemical evaluation in pulmonary neuroendocrine tumors.

Thyroid transcription factor-1 (TTF-1), a nuclear transcription protein selectively expressed in the thyroid, the diencephalon, and respiratory epithelium, is expressed in more than 90% of pulmonary small cell carcinomas (SCLCs) and in almost 75% of pulmonary non-small cell carcinomas (NSCLCs), but it is absent in typical pulmonary carcinoids (TCs). Therefore, it was thought that SCLC and NSCLC might share a common lineage, different from that of TC. TTF-1 expression in atypical pulmonary carcinoids (ACs) and large-cell neuroendocrine carcinomas (LCNECs) was not studied previously. We examined TTF-1 expression in 51 TCs, 9 ACs, 8 LCNECs, and 21 SCLCs with use of formalin-fixed material and heat-induced epitope retrieval. TTF-1 expression was seen in 18 (35%) of 51 TCs, all of the 9 ACs, 6 (75%) of the 8 LCNECs, and 20 (95%) of the 21 SCLCs. These results reinforce earlier findings of the excellent sensitivity of TTF-1 for SCLC, and they show similar sensitivity for AC and LCNEC, but they argue against the hypothesis that SCLC and TC are of different cell lineages. The ubiquity of TTF-1 expression in pulmonary NECs demonstrated in this study also argues against its use in their subclassification.

Histological and anatomic changes in Barrett's esophagus after antireflux surgery.

OBJECTIVE: The best treatment approach for patients with documented Barrett's esophagus remains controversial. There is currently no well designed prospective study examining the effect of successful antireflux surgery on Barrett's esophagus. METHODS: Fourteen patients with histologically proven Barrett's esophagus underwent standard antireflux surgery followed by careful endoscopic, histological, and symptomatic follow-up beginning at 2-4 wk after surgery. Pre- and postoperative symptoms, patient functional assessment scores, lower esophageal sphincter pressure, and 24-h pH studies were compared, in addition to monitoring patients for evidence of squamous re-epithelialization and dysplasia. RESULTS: Patients demonstrated statistically significant improvement in symptoms, functional assessment scores, lower esophageal sphincter pressure, and 24-h pH assessments after antireflux surgery. Two patients had complete disappearance of short segments (2 and 3 cm) of Barrett's esophagus. Ten additional patients demonstrated evidence of squamous re-epithelialization, although biopsies often showed mixed components of squamous and columnar epithelium. No patients showed progression of dysplastic change, and four patients demonstrated the disappearance of low grade dysplasia throughout the period of the study. CONCLUSION: Successful antireflux surgery can produce at least partial squamous re-epithelialization in Barrett's metaplasia and stabilization or apparent improvement in dysplasia in some patients without the need for long term medication. Continued long term endoscopic and histologic follow-up is still required in all patients with Barrett's esophagus after antireflux surgery.

Primary lung tumors infiltrated by osteoclast-like giant cells.

Six primary lung tumors with numerous multinucleated osteoclast-like giant cells (OLGCs) and no osteogenic component were evaluated histologically and immunohistochemically to examine pulmonary lesions inciting an OLGC response. The patients comprised four women and two men ranging in age from 61 to 80 years (average age, 69 years). The tumors consisted of one adenocarcinoma, two sarcomatoid carcinomas, and three giant cell variants of malignant fibrous histiocytoma. One tumor was endobronchial in location, while five were situated peripherally. Tumor diameter spanned from 1 to 6.5 cm (average, 2.7 cm). In addition to the giant cells, common characteristics included the malignant nature of the neoplasms and, in five of six cases, histologically malignant mesenchyme. This array of cases exemplifies the variability of lung lesions which may elicit an OLGC inflammatory response resulting in areas resembling the giant cell variant of malignant fibrous histiocytoma. The results of this study suggest that OLGCs occur preferentially in malignant rather than benign nonosteogenic lung tumors and that sarcomatoid regions of malignant tumors are more likely to be infiltrated by OLGCs than epithelial regions.

Pulmonary epithelioid haemangioendothelioma in 21 patients, including three with partial spontaneous regression.

This investigation studied the general conditions and prognostic factors of pulmonary epithelioid haemangioendothelioma (PEH), which is a rare disease. Twenty-one patients were collected throughout Asia by a questionnaire. Age at the detection or onset of symptoms of PEH was 14-64 yrs (mean 44 yrs). Males were more likely to be detected by symptoms (4/8, 50%) than were females (1/13, 8%). Fifteen showed bilateral multiple nodular opacities. Partial spontaneous regression occurred in three asymptomatic patients (one male and two females, all with bilateral multiple nodular opacities) 5, 13 and 15 yrs after detection. Two of the three patients with pleural effusion died within 1 yr, while the 16 patients with no effusion were alive more than 1 yr later (p<0.05). Histologically, two patients with fibrinofibrous pleuritis and extrapleural proliferation of tumour cells died within 2 yrs, while only one of 14 patients lacking such manifestations died within the same period (p<0.05). All three patients without spindle tumour cells survived for 12 yrs after the diagnosis, while all four patients with such cells died during the same period (p<0.05). In conclusion, 21 patients with pulmonary epithelioid haemangioendothelioma were reported, of whom three demonstrated partial spontaneous regression, and adverse prognostic features were identified.

Reproducibility of the histologic diagnosis of pneumonia among a panel of four pathologists: analysis of a gold standard.

STUDY OBJECTIVE: To establish a histologic diagnosis of pneumonia by consensus of a panel of pathologists, to test the interobserver and intraobserver variation in the histologic diagnosis of pneumonia, to compare the diagnostic accuracy of diagnosing pneumonia with and without preselected histologic criteria, and to establish more specific histologic criteria for the diagnosis of pneumonia. METHODS: The study group consisted of 39 patients who died after a mean of 14 days of mechanical ventilation. A postmortem open lung biopsy was performed on all patients. The tissue was reviewed independently by four pathologists who categorized the slides from each patient as showing or not showing pneumonia. Interobserver variation was calculated using the kappa statistic. Six months following the initial evaluation, the same slides were resubmitted to one of the pathologists for reevaluation to look for intraobserver error. Finally, the slides were reviewed and categorized by the criteria of Johanson et al into no pneumonia, mild, moderate, or severe bronchopneumonia. A comparison was made of the patients selected as demonstrating histologic pneumonia by each of the examinations. RESULTS: The reliability coefficient (kappa) measuring agreement among the four pathologists was good at 0.916. However, the prevalence of pneumonia as determined by each of the four pathologists varied; pathologist A, 15 of 39 (38%); pathologist B, 12 of 39 (31%); pathologist C, 9 of 39 (23%); and pathologist D, 7 of 39 (18%). Resubmitting the same slides to the same pathologist 6 months later resulted in reclassification of 2 of 39 patients. Using the histologic criteria of Johanson and colleagues, 14 patients were selected as having pneumonia compared with only nine patients selected by consensus of three of four pathologists. CONCLUSIONS: Recognition of histologic pneumonia varies among pathologists. The preselected criteria of Johanson and colleagues detected histologic pneumonia in eight of nine patients picked by consensus of pathologists, but six additional patients classified as "no histologic pneumonia" by the consensus of pathologists were judged to have histologic pneumonia by these criteria. The results established the necessity for standardization of histologic criteria for studies using biopsy as the gold standard for bacterial pneumonia. An atlas showing the criteria used in our selection was developed.

Tc-99m sulfur colloid demonstration of diffuse pulmonary interstitial extramedullary hematopoiesis in a patient with myelofibrosis. A case report and review of the literature.

A 60-year-old man with a myeloproliferative syndrome and extramedullary hematopoiesis had progressive respiratory and cardiac insufficiency during the previous 18 months, with advancing interstitial pulmonary disease on chest x-ray. During analysis of his respiratory disease, results of a transbronchial biopsy showed interstitial involvement with increased numbers of megakaryocytes and other panhematopoietic staining elements. Results of a bone marrow scan demonstrated diffuse replacement of pulmonary interstitium with bone marrow, as a component of known ongoing extramedullary hematopoiesis.

Four varied cases of intravascular lymphomatosis and a literature review.

BACKGROUND: Intravascular lymphoma (IVL) is an uncommon malignancy defined pathologically by neoplastic proliferation of lymphoid cells within the lumens of capillaries, small veins, and arteries, with little or no adjacent parenchymal involvement. The nature of IVL has been the subject of considerable controversy. Recent immunohistochemical studies have demonstrated clearly that the tumors bear the immunophenotype of neoplastic lymphoid cells of either B-cell or T-cell lineage. IVL commonly affects the central nervous system, resulting in progressive dementia and multiple neurologic deficits; skin is the second most common site of involvement, in the form of cutaneous plaques and nodules. METHODS: In a retrospective review of all cases of non-Hodgkin's lymphoma seen at our institution, four cases of IVL were identified. Case 1 was fixed in methacarin, and Cases 2-4 were fixed in 10% formalin. Standard fixation, tissue processing, sectioning, and hematoxylin and eosin staining were used. Immunophenotypic studies were performed using a modified avidin-biotin complex technique. The specimen in Case 1 was stained by Giemsa stain using standard techniques. RESULTS: Four cases of IVL are presented. One patient experienced hypoxemia and fevers of unknown origin; the second, dementia and a vasculitislike illness; the third rapidly progressive dementia, nonlocalizing neurologic deficits, and panhypopituitarism; the fourth Kaposi-like skin lesions. Case 1 relapsed shortly after completing chemotherapy. Salvage chemotherapy has yielded good initial response. Autopsy findings in cases 2, 3 and 4 confirmed IVL in many vessels, including the brain, lung, liver, heart, gastrointestinal tract, glomerulus, central nervous system, and skin. Malignant lymphoid cells marked as B-cells in all cases. CONCLUSIONS: Unusual and interesting clinical presentations may occur in patients with IVL. The medical literature indicates that few cases are diagnosed ante mortem. Although isolated patients may respond favorably to chemotherapy, most will deteriorate rapidly and the diagnosis of IVL not contemplated until necropsy.