Invited review. The technique and scope of electron-probe X-ray analysis in pathology

Foreign body gingival lesions: distribution, morphology, identification by X-ray energy dispersive analysis and possible origin of foreign material

BACKGROUND

Foreign material may cause and aggravate gingival lesions. This is rarely considered clinically. The lesions are resistant to frequently protracted conventional therapy. The foreign material is often inconspicuous and easily overlooked by the pathologist.

METHODS

85 cases of gingival lesions containing foreign material were investigated by conventional and polarization light microscopy, focusing on the morphology and optical characteristics of the foreign substance. Supplemented with the results of X-ray energy dispersive analysis the foreign material was compared with commonly used dental materials.

RESULTS

The foreign material was most frequently compatible with amalgam. Inconspicuous crystals, often revealed only by polarization microscopy, were most commonly compatible with abrasives, particularly corundum and silicates, and mostly occurred together with amalgam dust.

CONCLUSIONS

Iatrogenic introduction of dental materials during dental procedures explains most foreign body gingival lesions which could be reduced or avoided by prophylactic measures. Pathologists should meticulously scrutinize gingival biopsies routinely applying polarization microscopy.

Calcification of intraocular hydrogel lens: evidence of dystrophic calcification

PURPOSE

To report and describe the surface calcification of three cases of implanted intraocular hydrogel lens.

METHODS

Three surgically extracted hydrogel intraocular lenses were studied by light and transmission electron microscopy as well as by energy dispersion X-ray microanalysis.

RESULTS

The lens surfaces were covered by granular deposits of calcium phosphate, clearly delineated by von Kossa and alizarin stains for calcium. Transmission electron microscopy showed the deposits to be located within the superficial lens material to a depth of 7 microm and to be associated with what appear to be traces of cellular material including basement membrane and plasmalemma. To the authors' knowledge there has been only one other transmission electron microscopic study. Energy dispersion X-ray microanalysis showed the deposits to contain calcium and phosphorous in all cases.

CONCLUSIONS

This study confirms and extends the previous reports of five cases of calcification of hydrogel intraocular lenses. The exact mechanism of calcification remains obscure but evidence suggesting cell-mediated dystrophic calcification of the lens surface is presented. Further study is required to monitor the incidence and development of this phenomenon.

Pigments of the gastrointestinal tract: a comparison of light microscopic and electron microscopic findings

It is now apparent that light microscopy and histochemistry failed to identify correctly the nature and composition of pigments in various gastrointestinal tract melanoses. In most instances it was thought that the pigment was melanin or a melanin-like substance. Electron microscopy (EM) and electron-probe energy dispersive x-ray analysis have rectified these errors and have shown the following: in melanosis coli the pigment granules contain lipofuscin; in melanoses ilei the pigment granules may contain either silicates and titanium or hemosiderin; and in melanosis duodeni the pigment granules contain iron sulfide. In melanosis esophagi it is not clear what the pigment is; it could be melanin or lipofuscin.

Melanoses of the gastrointestinal tract

Electronmicroscopy and electron probe energy dispersive X-ray analysis studies have substantially contributed to our understanding of the various gastrointestinal tract melanoses. The nature of the pigment granules which occur in the various melanoses is discussed; their pattern of distribution in melanosis coli, melanosis ilei, melanosis duodeni and melanosis oesophagi is summarized and current knowledge of the aetiology and pathogenesis of these conditions is reviewed. Brief mention is also made of other examples of lipofuscin pigmentation, and a case of haemosiderosis ilei is described.

Paradoxical embolisation of a catheter fragment to a coronary artery in an infant with congenital heart disease

Six weeks after cardiac catheterisation via the right femoral vein an infant underwent an anatomical correction for transposition of the great vessels and closure of a large ventricular septal defect. The patient died intraoperatively as a result of severe left ventricular dysfunction. Necropsy showed an old myocardial infarction associated with thrombosis of the circumflex coronary artery. Electron probe x ray analysis showed that foreign refractile material within the thrombus contained bismuth, an element used in the construction of some cardiac catheters. This is believed to be the first report of "paradoxical" coronary embolisation of catheter-derived material and highlights the usefulness of electron probe x ray analysis.

Practical applications of energy dispersive X-ray microanalysis in diagnostic oral pathology

Energy dispersive X-ray microanalysis is a powerful tool that can reveal the presence and relative quantities of elements in minute particles in biologic materials. Although this technique has been used in some aspects of dental research, it has rarely been applied to diagnostic oral pathology. The purpose of this paper is to inform practicing dentists and oral specialists about the diagnostic potential of this procedure by presenting three case reports. The first case involved the identification of flakes of a metallic material claimed by a 14-year-old girl to appear periodically between her mandibular molars. In the second case, a periodontist was spared a lawsuit when a freely mobile mass in the antrum of his patient was found to be a calcium-phosphorus compound not related to the periodontal packing that had been used. The third case involved the differential diagnosis of amalgam tattoo and graphite tattoo in a pigmented lesion of the hard palate mucosa. The results of the analyses were significant and indicate a role for this technique in the assessment of selected cases. Potential for wider use of energy dispersive X-ray microanalysis in diagnostic oral pathology exists as research progresses.

The use of elemental microanalysis in verification of the composition of presumptive amalgam tattoo

Routine histochemistry, special stains, and energy dispersive x-ray microanalysis (EDX) were used to analyze 15 cases of presumptive amalgam tattoo. Histologically, the fine, spherical, golden brown granules of amalgam were remarkably similar to hemosiderin and melanin granules, and routine and special stains were not always reliable in differentiating one from the others. EDX provided a simple, fast, inexpensive, and reliable method for identifying the precise elemental composition of the pigmented material.

Analytical approaches for biomedical elemental analysis

Several different analytical systems are available for biomedical elemental analysis related to human nutrition. The principle, detection limits, analytical artifacts, and applications are presented for the following analytical systems for elemental analysis classified by sample volume: macro volume systems--flame atomic absorption spectroscopy (FAAS) and inductively coupled plasma (ICP); micro volume systems--electrothermal atomization (graphite furnace) atomic absorption spectroscopy (ETA-AAS) and x-ray fluorescence (XRF); and ultramicro volume systems--electron probe x-ray microanalysis (EPX) and laser microprobe mass analysis (LAMMA).

Value of in situ elemental microanalysis in the histologic diagnosis of silicosis

Pulmonary specimens obtained from ten normal subjects and 53 patients with various pulmonary diseases were studied with energy-dispersive x-ray analysis. The amount of silicon in the pulmonary tissue was determined and expressed as a silicon/sulfur (Si/S) ratio. This Si/S ratio was below 0.2 in the ten normal subjects and in 14 patients who had various interstitial pulmonary diseases but had no previous history of exposure to silica or other dusts known to cause pulmonary fibrosis. The Si/S ratio was greater than 0.3 in 19 of 22 patients who had a history of exposure to silica dust and had clear-cut histologic evidence of silicosis. The Si/S ratio was less than 0.2 in 12 and between 0.2 and 0.3 in two of the 14 patients who had a history of exposure to silica dusts but no clinical or histologic evidence of silicosis. We conclude that the determination of the silicon content of tissue by energy-dispersive x-ray analysis is useful in separating the fibrosis due to silicosis from the other causes of pulmonary fibrosis.

Applications of electron microscopy to diagnostic pulmonary pathology

Viruses and other possible causative agents should be sought light and electron microscopically in all cases of ill-defined diseases including "sarcoid." Ideally, tissue should be prepared for electron microscopic examination as soon as a specimen is obtained; however, when this has not been done, tissue preserved in formalin solution can be used. Viruses, some bacteria, and other agents suspected on the basis of light microscopic findings can be verified electron microscopically by reprocessing paraffin-embedded tissue from areas that show smudge cells, focal necrosis with atypical cellular proliferation, and nuclear inclusions. Electron microscopically, all dying cells show swelling and rupture of cellular organelles and membranes; reactive changes include proliferation of branching tubules and paracrystalline and other types of proteinaceous precipitates (inclusions) in both the nucleus and cytoplasm. Qualitative and quantitative changes of cellular organelles, fibrils, microvilli, and intercellular junctions reflect hyperplasia, metaplasia, or dysplasia of the cell and may enable identification of the diseases, e.g., desquamative interstitial pneumonia. In various conditions, basal laminae become irregular, disruptive, or reduplicated following epithelial necrosis and regeneration. Electron microscopic evidence of immunologic damage to basal lamina and cells and immuno-electron-microscopic features of the lung in general require further studies. Electron microscopic features of transbronchial biopsy specimens may be diagnostic in cases of alveolar proteinosis, histiocytosis X, and amyloidosis. Ultrastructural abnormalities of cilia are common; primary ciliary defects are rare. Finally, light microscopic, scanning electron microscopic, and x-ray energy-dispersive spectrometric examinations of paraffin-embedded sections appear most practical for the pathologic evaluation of cases of pneumoconiosis.

Scanning energy dispersive X-ray analysis of intraocular foreign material

Energy dispersive X-ray analysis is recognized as a most useful technique in research. Its diagnostic applications are being rapidly developed. We describe a case of corneal, lenticular and retinal damage in an eye without a documented history of trauma. Scanning energy dispersive X-ray analysis of foreign material in the lens helped to elucidate the probable cause of the injury. The medico-legal implications of this case are briefly discussed.

Uraniosomes produced in cultured rabbit kidney cells by uranyl acetate

Cultured rabbit kidney cells were exposed to uranyl acetate. This produced single-membrane-bound presumably lysosomal bodies (called 'uraniosomes') containing electron-dense crystals in the cultured cells. Similar crystalline deposits were seen in extracellular locations also. All uraniosomes and extracellular uranium deposits analyzed by electron-probe x-ray analysis were found to contain uranium, potassium, calcium and phosphorus. Traces of sulphur were detected in some but not all uraniosomes and extracellular uranium deposits.

Aluminum associated bone disease: clinico-pathologic correlation

A chemical, aurine tricarboxylic acid was used to identify aluminum in bone in a group of chronic renal failure patients with severe osteomalacia. Thirteen out of 49 (26%) patients had a positive stain at the bone-osteoid junction. The presence of aluminum at the staining site was confirmed by electron dispersion x-ray analysis. The patients' biopsies staining negative with this clinical, although having high bone aluminum levels, had more significant features of hyperparathyroidism, both biochemically and histologically than those having a positive stain. The usefulness of this technique to diagnose presymptomatic aluminum related osteomalacia is emphasized.

Ultrastructural and Energy dispersive analysis of inorganic inclusions in a muscle biopsy

A muscle biopsy that, by light microscopy, exhibited mild atrophy consistent with chronic denervating disease was submitted for ultrastructural analysis. Inorganic structures within the tissue were defined by energy dispersive analysis as aluminosilicates, magnesium silicates, and iron deposits. These structures were localized in the interstitial (intercollagenous) area and in high concentrations within degenerated muscle bundles. An alteration of the blood/muscle barrier has obviously occurred; however, the extent to which the end result commonly occurs in humans is unknown. Clarification of the question raised by this observation will have to be derived from animal studies, and clinicians must have an awareness of the need for electron microscopy/energy-dispersive x-ray analysis in muscle biopsies from patients with similar therapeutic backgrounds.

Ultrastructural localization and in situ analysis of iron, bismuth, and gold inclusions

The purpose of this article is to review ultrastructural and electron probe X-ray analytical studies on metallic deposits in cells. The metals that will be dealt with are iron, bismuth, and gold, mainly because they have been extensively studied in recent years. The nature and chemical composition of endogenously (e.g., from breakdown of autologous blood) and exogenously (e.g., after a transfusion or injection of iron compounds) produced hemosiderin (i.e., iron deposits) has been the subject of time-hallowed controversies. Quite a few of these have now been resolved by ultrastructural studies and the atomic composition of such deposits has been determined by electron probe X-ray analysis. The interest in bismuth centers around the fact that this is one of the two metals (the other being lead) that produces quite large intranuclear inclusions. Here again much has been learned by ultrastructural and X-ray analytical studies. The interest in gold stems from the fact that soluble salts of this metal are used for the treatment of rheumatoid arthritis and current studies with the above-mentioned techniques indicates how gold produces its beneficial and toxic effects.

Biological X-ray microanalysis

By means of X-ray microanalysis it is now practical to detect approximately 10(-19) g of an element in a static-probe analysis within an ultrathin section, with analytical spatial resolution in the range 20--30 nm. The main difficulties for biological microanalysis are connected not with sensitivity but with specimen preparation and beam damage. Careful cryopreparation, beginning with the quench-freezing of a small block of tissue, is essential even for determining the storage sites, or sites of binding in vivo, of physiologically active elements. In frozen-dried or frozen-hydrated sections of quench-frozen tissue, it is now possible to measure local mass fractions of diffusible as well as of bound elements.