Calcification in human breast carcinomas: ultrastructural observations

Multiple Pathways for Pathological Calcification in the Human Body

Biomineralization of skeletal components (e.g., bone and teeth) is generally accepted to occur under strict cellular regulation, leading to mineral-organic composites with hierarchical structures and properties optimized for their designated function. Such cellular regulation includes promoting mineralization at desired sites as well as inhibiting mineralization in soft tissues and other undesirable locations. In contrast, pathological mineralization, with potentially harmful health effects, can occur as a result of tissue or metabolic abnormalities, disease, or implantation of certain biomaterials. This progress report defines mineralization pathway components and identifies the commonalities (and differences) between physiological (e.g., bone remodeling) and pathological calcification formation pathways, based, in part, upon the extent of cellular control within the system. These concepts are discussed in representative examples of calcium phosphate-based pathological mineralization in cancer (breast, thyroid, ovarian, and meningioma) and in cardiovascular disease. In-depth mechanistic understanding of pathological mineralization requires utilizing state-of-the-art materials science imaging and characterization techniques, focusing not only on the final deposits, but also on the earlier stages of crystal nucleation, growth, and aggregation. Such mechanistic understanding will further enable the use of pathological calcifications in diagnosis and prognosis, as well as possibly provide insights into preventative treatments for detrimental mineralization in disease.

Multi-gene signature of microcalcification and risk prediction among Taiwanese breast cancer

Microcalcification is one of the most common radiological and pathological features of breast ductal carcinoma in situ (DCIS), and to a lesser extent, invasive ductal carcinoma. We evaluated messenger RNA (mRNA) transcriptional profiles associated with ectopic mammary mineralization. A total of 109 breast cancers were assayed with oligonucleotide microarrays. The associations of mRNA abundance with microcalcifications and relevant clinical features were evaluated. Microcalcifications were present in 86 (79%) patients by pathological examination, and 81 (94%) were with coexistent DCIS, while only 13 (57%) of 23 patients without microcalcification, the invasive diseases were accompanied with DCIS (χ²-test, P < 0.001). There were 69 genes with differential mRNA abundance between breast cancers with and without microcalcifications, and 11 were associated with high-grade (comedo) type DCIS. Enriched Gene Ontology categories included glycosaminoglycan and aminoglycan metabolic processes and protein ubiquitination, indicating an active secretory process. The intersection (18 genes) of microcalcificaion-associated and DCIS-associated genes provided the best predictive accuracy of 82% with Bayesian compound covariate predictor. Ten genes were further selected for prognostic index score construction, and five-year relapse free survival was 91% for low-risk and 83% for high-risk group (log-rank test, P = 0.10). Our study suggested that microcalcification is not only the earliest detectable radiological sign for mammography screening but the phenomenon itself may reflect the underling events during mammary carcinogenesis. Future studies to evaluate the prognostic significance of microcalcifications are warranted.

Studying biomineralization pathways in a 3D culture model of breast cancer microcalcifications

Microcalcifications serve as diagnostic markers for breast cancer, yet their formation pathway(s) and role in cancer progression are debated due in part to a lack of relevant 3D culture models that allow studying the extent of cellular regulation over mineralization. Previous studies have suggested processes ranging from dystrophic mineralization associated with cell death to bone-like mineral deposition. Here, we evaluated microcalcification formation in 3D multicellular spheroids, generated from non-malignant, pre-cancer, and invasive cell lines from the MCF10A human breast tumor progression series. The spheroids with greater malignancy potential developed necrotic cores, thus recapitulating spatially distinct viable and non-viable areas known to regulate cellular behavior in tumors in vivo. The spatial distribution of the microcalcifications, as well as their compositions, were characterized using nanoCT, electron-microscopy, and X-ray spectroscopy. Apatite microcalcifications were primarily detected within the viable cell regions and their number and size increased with malignancy potential of the spheroids. Levels of alkaline phosphatase decreased with malignancy potential, whereas levels of osteopontin increased. These findings support a mineralization pathway in which cancer cells induce mineralization in a manner that is linked to their malignancy potential, but that is distinct from physiological osteogenic mineralization.

Correlative imaging reveals physiochemical heterogeneity of microcalcifications in human breast carcinomas

Microcalcifications (MCs) are routinely used to detect breast cancer in mammography. Little is known, however, about their materials properties and associated organic matrix, or their correlation to breast cancer prognosis. We combine histopathology, Raman microscopy, and electron microscopy to image MCs within snap-frozen human breast tissue and generate micron-scale resolution correlative maps of crystalline phase, trace metals, particle morphology, and organic matrix chemical signatures within high grade ductal carcinoma in situ (DCIS) and invasive cancer. We reveal the heterogeneity of mineral-matrix pairings, including punctate apatitic particles (<2 µm) with associated trace elements (e.g., F, Na, and unexpectedly Al) distributed within the necrotic cores of DCIS, and both apatite and spheroidal whitlockite particles in invasive cancer within a matrix containing spectroscopic signatures of collagen, non-collagen proteins, cholesterol, carotenoids, and DNA. Among the three DCIS samples, we identify key similarities in MC morphology and distribution, supporting a dystrophic mineralization pathway. This multimodal methodology lays the groundwork for establishing MC heterogeneity in the context of breast cancer biology, and could dramatically improve current prognostic models.

Secretory pathway Ca2+ -ATPases promote in vitro microcalcifications in breast cancer cells

Calcification of the breast is often an outward manifestation of underlying molecular changes that drive carcinogenesis. Up to 50% of all non-palpable breast tumors and 90% of ductal carcinoma in situ present with radiographically dense mineralization in mammographic scans. However, surprisingly little is known about the molecular pathways that lead to microcalcifications in the breast. Here, we report on a rapid and quantitative in vitro assay to monitor microcalcifications in breast cancer cell lines, including MCF7, MDA-MB-231, and Hs578T. We show that the Secretory Pathway Ca²⁺ -ATPases SPCA1 and SPCA2 are strongly induced under osteogenic conditions that elicit microcalcifications. SPCA gene expression is significantly elevated in breast cancer subtypes that are associated with microcalcifications. Ectopic expression of SPCA genes drives microcalcifications and is dependent on pumping activity. Conversely, knockdown of SPCA expression significantly attenuates formation of microcalcifications. We propose that high levels of SPCA pumps may initiate mineralization in the secretory pathway by elevating luminal Ca²⁺ . Our new findings offer mechanistic insight and functional implications on a widely observed, yet poorly understood radiographic signature of breast cancer.

A perspective of comparative salivary and breast pathology. Part I: microstructural aspects, adaptations and cellular events

This is the first part of a review comparing the pathology of salivary and mammary glands. Here, less obvious similarities and differences in functional histology and their influences on pathology are examined with emphasis on myoepithelial cells, stromal components, analogues of mucosa-associated lymphoid tissue, steroid receptors, and intraparenchymal cells of monocytic lineage. Particular cell phenotypes (oncocytic, apocrine, neuroendocrine and clear) are critically evaluated and responses to atrophy, infarction and fine-needle aspiration biopsy procedures are highlighted together with aspects of metaplasia, regeneration, ageing and microcalcification. Areas of controversy or uncertainty which may benefit from further investigations are also discussed.

Microcalcifications in breast cancer: Lessons from physiological mineralization

Mammographic mammary microcalcifications are routinely used for the early detection of breast cancer, however the mechanisms by which they form remain unclear. Two species of mammary microcalcifications have been identified; calcium oxalate and hydroxyapatite. Calcium oxalate is mostly associated with benign lesions of the breast, whereas hydroxyapatite is associated with both benign and malignant tumors. The way in which hydroxyapatite forms within mammary tissue remains largely unexplored, however lessons can be learned from the process of physiological mineralization. Normal physiological mineralization by osteoblasts results in hydroxyapatite deposition in bone. This review brings together existing knowledge from the field of physiological mineralization and juxtaposes it with our current understanding of the genesis of mammary microcalcifications. As an increasing number of breast cancers are being detected in their non-palpable stage through mammographic microcalcifications, it is important that future studies investigate the underlying mechanisms of their formation in order to fully understand the significance of this unique early marker of breast cancer.

Molecular pathology of breast apocrine carcinomas: A protein expression signature specific for benign apocrine metaplasia

Breast cancer is a heterogeneous disease that encompasses a wide range of histopathological types including: invasive ductal carcinoma, lobular carcinoma, medullary carcinoma, mucinous carcinoma, tubular carcinoma, and apocrine carcinoma among others. Pure apocrine carcinomas represent about 0.5% of all invasive breast cancers according to the Danish Breast Cancer Cooperative Group Registry, and despite the fact that they are morphologically distinct from other breast lesions, there are at present no standard molecular criteria available for their diagnosis. In addition, the relationship between benign apocrine changes and breast carcinoma is unclear and has been a matter of discussion for many years. Recent proteome expression profiling studies of breast apocrine macrocysts, normal breast tissue, and breast tumours have identified specific apocrine biomarkers [15-hydroxyprostaglandin dehydrogenase (15-PGDH) and hydroxymethylglutaryl coenzyme A reductase (HMG-CoA reductase)] present in early and advanced apocrine lesions. These biomarkers in combination with proteins found to be characteristically upregulated in pure apocrine carcinomas (psoriasin, S100A9, and p53) provide a protein expression signature distinctive for benign apocrine metaplasias and apocrine cystic lesions. These studies have also presented compelling evidence for a direct link, through the expression of the prostaglandin degrading enzyme 15-PGDH, between early apocrine lesions and pure apocrine carcinomas. Moreover, specific antibodies against the components of the expression signature have identified precursor lesions in the linear histological progression to apocrine carcinoma. Finally, the identification of proteins that characterize the early stages of mammary apocrine differentiation such as 15-PGDH, HMG-CoA reductase, and cyclooxygenase 2 (COX-2) has opened a window of opportunity for pharmacological intervention, not only in a therapeutic manner but also in a chemopreventive setting. Here we review published and recent results in the context of the current state of research on breast apocrine cancer.

An etiologic model proposing that sporadic adult-onset carcinoma is extramedullary hematopoiesis

This model proposes that primary carcinomatous tumors and almost all metastases are extramedullary hematopoietic tissue formed to compensate for reduced hematopoietic activity in the bone marrow. These marrow lesions are currently considered to be metastatic in origin, but as fibrosis and sclerosis are identifying features they are here equated to myelofibrosis. Myelofibrotic marrow is characterized by an increase in the number and size of vascular sinusoids. The increased blood flow suggested by this morphology, and observed in myelofibrosis patients, causes a rise in marrow pressure which may trigger the fibrosis. Specific carcinoma morphologies are equated to stages in endochondral bone and marrow formation and, as such, cancer cell identity varies with morphology. For example, infiltrating carcinomas of the breast consist of collagen and mucoid secreting cells in single file formation. This morphology is equated to the cartilagenous stage of marrow formation, when mesenchymal stem cells proliferate and differentiate into chondroblasts. In this model "infiltrating" cells arise in situ from stem cells located in the connective tissue. Tubular breast carcinoma, with its single layer of osteoblast-like carcinoma cells encircling small lumens and long branching tubules, is equated to the trabecular stage of marrow formation during which osteoblasts surround small pieces of calcified cartilage and begin secreting osteoid that will form the trabeculae. Lobular carcinoma in situ consists of cancer cell clusters separated by narrow clear spaces that, under high magnification, appear vascular. This morphology is equated to hematopoietic tissue in which primitive hematopoietic cells lie between anastomosing sinusoids. Similar cartilagenous, trabecular and hematopoietic morphologies can be found in carcinomatous tumors of most organs, but the nomenclature is variable. The hematopoietic carcinomas share numerous features with hematopoietic tissue including a structure composed of intermingled normoxic and hypoxic regions and a metabolism characterized by elevated levels of glycolysis. They also contain similar proportions of clonal cells. If this model is correct it necessitates a change in the treatment of carcinoma. If cancer cells are not the enemy, but desperately needed immature blood cells, and the medical problem is not the presence of tumors, but the inefficiency of this extramedullary hematopoietic tissue, then treatment should focus on increasing marrow hematopoiesis. As evidence suggests that the marrow lesion is the result of increased hydrostatic pressure this could be done by reducing blood volume. One way to accomplish this may be through the ingestion of ephedrine, as it is hypothesized to increase vascular tone.

Apocrine cysts of the breast: biomarkers, origin, enlargement, and relation with cancer phenotype

Up to one-third of women aged 30-50 years have cysts in their breasts and are presumed to be at increased risk of developing breast cancer. Here we present an extensive proteomic and immunohistochemistry (IHC) study of breast apocrine cystic lesions aimed at generating specific biomarkers and elucidating the relationship, if existent, of apocrine cysts with cancer phenotype. To this end we compared the expression profiles of apocrine macrocysts obtained from mastectomies from high risk cancer patients with those of cancerous and non-malignant mammary tissue biopsies collected from the same patients. We identified two biomarkers, 15-hydroxyprostaglandin dehydrogenase and 3-hydroxymethylglutaryl-CoA reductase, that were expressed specifically by apocrine type I cysts as well as by apocrine metaplastic cells in type II microcysts, terminal ducts, and intraductal papillary lesions. No expression of these markers was observed in non-malignant terminal ductal lobular units, type II flat cysts, stroma cells, or fat tissue as judged by IHC analysis of matched non-malignant tissue samples collected from 93 high risk patients enrolled in our cancer program. IHC analysis of the corresponding 93 primary tumors indicated that most apocrine changes have little intrinsic malignant potential, although some may progress to invasive apocrine cancer. None of the apocrine lesions examined, however, seemed to be a precursor of invasive ductal carcinomas, which accounted for 81% of the tumors analyzed. Our studies also provided some insight into the origin, development, and enlargement of apocrine cysts in mammary tissue. The successful identification of differentially expressed proteins that characterize specific steps in the progression from early benign lesions to apocrine cancer opens a window of opportunity for designing and testing new approaches for pharmacological intervention, not only in a therapeutic setting but also for chemoprevention, to inhibit cyst development as both 15-hydroxyprostaglandin dehydrogenase and 3-hydroxymethylglutaryl-CoA reductase are currently being targeted for chemoprevention strategies in various malignancies.

Microcalcifications associated with breast cancer: an epiphenomenon or biologically significant feature of selected tumors?

Radiographic mammary calcifications occur in 30-50% of breast cancers and constitute one of the most important diagnostic markers of both benign and malignant lesions of the breast. The presence of oxalate-type microcalcification appears to be a reliable criterion in favor of the benign nature of the lesion or, at most, of a lobular carcinoma in situ. In contrast, calcium hydroxyapatite (HA) crystals are associated with both benign and malignant breast tumors. Although the diagnostic value of microcalcifications in breast cancer is of great importance, the genesis of these calcifications is unclear. Despite numerous histological ultrastructure studies of HA deposits in breast carcinomas, to date there have been limited investigations of the potential role of these crystals in breast cancer. We review the literature examining the biological effects of HA crystals in breast cancer cell lines, specifically the mechanism of HA-induced mitogenesis and upregulation of gene expression.

Calcifications in ovary and endometrium and their neoplasms

In this study, we investigated the role of hormones in the pathogenesis of calcifications in ovary and in endometrium and their neoplasms of the gynecologic tract and assessed the anatomic location and incidence of these calcifications. The study consists of three parts designed to investigate the pathogenesis, the location, and the incidence of calcifications in ovary and endometrium and their neoplasms. In the first part, 79 female guinea pigs were divided into 10 groups, and different hormones, given weekly for 12 months, were administered to the guinea pigs by group. A control group of 7 guinea pigs received sterile water. Calcifications developed in 5 of 7 guinea pigs treated with prolactin, 10 of 20 treated with human chorionic gonadotropin, 5 of 11 treated with estradiol, 3 of 7 treated with estrone, 1 of 6 treated with growth hormone, and 1 of 10 treated with testosterone; in 20 of the guinea pigs, the calcifications developed in the stroma of the endometrium, and in 5 guinea pigs, they developed in the ovary. The second part of the study consisted of an evaluation of the specific location of calcifications in 43 consecutive human surgical ovaries and endometria. Calcifications were seen only in the stroma in 100% of the ovarian serous adenofibroma specimens; in ovarian serous borderline neoplasms, the stroma contained 70 to 100% of the calcifications, and the epithelium had 0 to 30% of the calcifications. In ovarian serous carcinoma specimens, the calcifications were seen in the stroma in 50 to 60% of the cases, in the epithelium in 40% of the cases, and in areas of necrosis in 10% of the cases. The third part of the study was directed to determine the frequency of calcifications in ovarian lesions. We found that all cases of endosalpingiosis and ovarian low-grade serous carcinoma had calcifications, whereas 80% of the cases of serous borderline tumor had calcifications, and only 50% of the cases of ovarian high-grade serous carcinoma contained calcifications. The results of this study indicate that the majority of the calcifications in the ovary and the endometrium and their neoplasms are present in the stroma. This is most probably secondary to metabolic changes, which could be related to hormones and not caused by degenerative changes in epithelial cells.

Calcium hydroxyapatite promotes mitogenesis and matrix metalloproteinase expression in human breast cancer cell lines

Radiographic mammary microcalcifications are one of the most pertinent diagnostic markers of breast cancer. Breast tissue calcification in the form of calcium hydroxyapatite (HA) is strongly associated with malignant disease. We tested the hypothesis that calcium HA may exert biological effects on surrounding cells, thereby facilitating breast cancer progression. Our findings showed that HA crystals enhanced mitogenesis in breast cancer cell lines MCF-7 and Hs578T and also in normal human mammary epithelial cells. HA crystals were also found to upregulate the production of a variety of matrix metalloproteinases (MMPs), including MMP-2, -9, and -13 in MCF-7 and MMP-9 in human mammary epithelial cell lines. HA crystals were found to greatly augment prostaglandin E(2) levels in Hs578T cells, and treatment with a cyclooxygenase inhibitor, aspirin, abrogated the HA-induced mitogenesis. These results suggest that calcium HA crystals may play an active role in amplifying the pathological process involved in breast cancer.

Microcalcifications in the anterior pituitary gland of the fetus and the newborn: a histochemical and immunohistochemical study

Calcified concretions are a normal and constant finding in the anterior pituitary gland of fetuses and newborns. Their light and electron microscopic characteristics have been recently reported by the authors. In this study, undecalcified and decalcified sections from 20 neonatal and 60 fetal anterior pituitary glands were studied by histochemical and immunohistochemical methods to further clarify their nature and mechanism of formation. All the glands revealed homogeneous and/or laminar calcifications located either within the interstitium or follicular structures. They were composed of a diastase-resistant periodic acid-Schiff-positive carbohydrate-rich matrix. The Feulgen method for DNA was negative. Their core frequently reacted to Alcian blue and epithelial membrane antigen (EMA). EMA also stained the apical membranes of adjacent epithelial cells. Other immunostains (vimentin, keratin, and pituitary hormones) were negative. The positive staining for Alcian blue and EMA and the negative staining with the Feulgen method for DNA suggest that the core of the calcifications consists of acidic mucosubstances and EMA-positive proteinaceous material previously secreted by viable pituitary cells. The EMA-negative periphery of the concretions probably develops from further extracellular peripheral mineralization that leads to larger, sometimes laminated psammoma bodies. The occurrence of pituitary calcifications in states of adult physiological and pathological hyperprolactinemia suggests that the marked proliferation of lactotrophs occurring during the fetal life play an important role in the pathogenesis of the fetal and neonatal concretions.

The significance of spontaneous resolution of breast calcification

Spontaneously resolving breast microcalcification is a rarely reported occurrence. A retrospective review was carried out on 33 cases of resolving benign and indeterminate microcalcification identified from 108,000 screening mammograms from the South West London Breast Screening Service. Four further cases are reported from The Jarvis Breast Screening Centre. No interval cancers were identified in women with microcalcification which initially showed benign appearances. However, 36.4% of the group with resolving indeterminate microcalcification subsequently developed cancers. It is recommended that this change should prompt full investigation and close follow-up or excision. While the majority of spontaneously resolving microcalcification is associated with benign processes, it is concluded that a significant proportion of disappearing indeterminate microcalcification is associated with malignancy.

Segmentation algorithms for detecting microcalcifications in mammograms

The presence of microcalcification clusters in mammograms contributes evidence for the diagnosis of early stages of breast cancer. In many cases, microcalcifications are subtle and their detection can benefit from an automated system serving as a diagnostic aid. The potential contribution of such a system may become more significant as the number of mammograms screened increases to levels that challenge the capacity of radiology clinics. Many techniques for detecting microcalcifications start with a segmentation algorithm that indicates all candidate structures for the subsequent phases. Most algorithms used to segment microcalcifications have aspects that might raise operational difficulties, such as thresholds or windows that must be selected, or parametric models of the data. We present a new segmentation algorithm and compare it to two other algorithms: the multi-tolerance region growing algorithm that operates without the aspects mentioned above, and the active contour model that has not been applied previously to segment microcalcifications. The new algorithm operates without threshold or window selection, or parametric data models, and it is more than an order of magnitude faster than the other two.

Computerized Image Analysis of Clustered Microcalcifications on Mammography: Morphome- tric Comparison between Mammography and Pathology

The clusters of microcalcifications under 2 cm in greatest dimension were analyzed in terms of size and shape by an image processor with a computer after being magnified 33 times. The mean diameter of mammographic microcalcifications was 188 µ m in benign cases, 226µ m in cribriform or papillary type cancer cases, 213 µ m in intermediate type cancer cases, and 324µ m in comedo type cancer cases, showing significant differences among the groups. The size distribution of mammographic microcalcifications in the comedo type was characteristic, showing a second peak in distribution between 500 and 700µ m. The radiodensity of microcalcifications compared to the breast parenchyma, the caliber of breast ducts containing the malignant calcifications, and the unit volume of calcium deposits within the ductal lumens were greater in cancer cases. The size and shape of mammographic microcalcifications were considered to be related to a combination of the caliber of breast ducts, unit volume of calcium deposits within the ductal lumens, and the density of breast ducts containing calcium deposits. Duct calibers were generally larger in cases of cancer lesions than cases of benign lesions such as duct papillomatosis, thus calcium deposits and microcalcifications were greater in the cancer lesion. Uneven distrubution of size and form of microcalcifications over 250 µ m in size, and increased radiodensity of calcifications were useful parameters for differential diagnosis rather than the density of calcifications.

Calcium oxalate crystals in benign breast cyst fluid

We have recently observed a strongly birefringent material of varying shapes and sizes in a benign breast cyst fluid specimen from a 52-yr-old woman with suspicious mammographic microcalcifications. The finding of calcium oxalate crystals in the breast cyst fluid should be regarded as a recognition of a particular type of calcification, easily overlooked with the conventional light microscopy. To date, we are unaware of any cytologic reports of this type of calcification in the breast.

Ectopic mineralized cartilage formation in human undifferentiated pancreatic adenocarcinoma explants grown in nude mice

Mineralized as well as nonmineralized cartilage-like structures enclosing cells resembling chondrocytes were found in human-derived undifferentiated but not in poorly differentiated pancreatic adenocarcinoma explants grown in nude mice. The structures reacted with anti-mouse IgG but not with antibodies against human cytokeratin 19, indicating that the newly formed tissue was of mouse origin. High activity of alkaline phosphatase was found in cell layers surrounding the structures and in cells embedded in the matrix. The extracellular matrix was strongly positive after Sirius red staining, reacted with anti-collagen type II antibodies, and the presence of proteoglycans was demonstrated with Alcian blue staining and by metachromasia after Giemsa staining. Electron microscopic inspection revealed the presence of bundles of both thick collagenous fibrils with low levels of fine filamentous material and thin collagenous fibrils with high concentrations of filamentous components. The majority of both types of matrices was found to be partially or completely calcified. The mean area density of the cartilage-like structures in the undifferentiated tumors was 0.31%. The frequent formation of the cartilage-like structures in the rapidly growing undifferentiated explants and its absence in the slowly growing, more differentiated explants suggest that low oxygen tensions in combination with altered levels of growth factors, such as members of the transforming growth factor beta superfamily, create conditions that induce differentiation of fibroblasts to chondrocytes. It is concluded that these human tumors grown in nude mice can be used as an in vivo model to study ectopic formation of mineralized cartilage.

Light and electron microscopic study of an invasive cribriform carcinoma with extensive microcalcification developing in a breast with silicone augmentation

Although recent epidemiologic studies suggest that silicone augmentation of the breast is not associated with an increased risk of mammary carcinoma, cases of breast carcinoma arising in augmented breasts are being increasingly encountered as a large number of patients who had augmentation are getting older. A case of a 51-year-old woman with a 20-year history of breast augmentation who developed an invasive cribriform carcinoma associated with extensive microcalcification is presented. The patient had submammary silicone implants 20 years ago that were replaced, because of local complications, in subpectoral positions 10 years later. Dispersive X-ray microanalysis failed to demonstrate silicone in sections of the tumor and adjacent breast tissue. Appropriately fixed tumor tissue was available for electron microscopic examination. The tumor cells were rich in mitochondria, and their luminal surfaces were endowed with abundant microvilli, but the cell surfaces that came closest to the calcified microspheriols were devoid of microvilli and had cellular buddings between the microspheriols. It is suggested that the tumor cells might have been actively involved in the process of microcalcification.

Evaluation of abnormal screening mammograms

The purpose of routine screening mammography is to detect unsuspected cancer that has the potential to be cured. Abnormalities detected on the screening examination often necessitate additional radiologic workup before a definitive result or diagnosis can be given. This workup (diagnostic mammography) may include specialized views, such as spot compression to evaluate the margins of a nodule, or magnification views to determine the features of microcalcifications. Additional evaluation with mammographic views, breast ultrasound, and, at times, interventional procedures such as fine needle aspiration or core biopsy are performed to complete the radiologic evaluation of a patient with an abnormal mammogram. Signs of malignancy include nodules (most often poorly defined), microcalcifications, and, less commonly, areas of architectural distortion, asymmetry, or focal ductal dilatation. A comprehensive approach to breast imaging will help to potentiate the early detection of subtle malignancies and avoid the performance of some biopsies for benign lesions.

Histochemical and biochemical determination of calcium in pleomorphic adenoma

Although calcification seldom occurs in pleomorphic adenoma, it often occurs in salivary glands, and so we decided to investigate the possible role of calcium in this difference. A histochemical method using glyoxal bis(2-hydroxyanil) demonstrated a small amount of calcium outlining lumina and separated cells of epithelial structures and associated with cells of myxoid and chondroid regions in pleomorphic adenoma, and a conspicuous amount in the acini of the associated salivary glands. A biochemical method using dry ashing demonstrated a significantly higher level of calcium in the glands than in pleomorphic adenoma. The results indicate that the calcium is mainly associated with secretory granules, which are scarce in pleomorphic adenoma, and with proteoglycan present intercellularly and in stromal regions of pleomorphic adenoma. The calcium in secretory granules is of possible importance in calcification in lumina and epithelium, and that bound to proteoglycan is possibly released following necrosis to be of importance in stromal calcification. However, the overall low level of calcium in pleomorphic adenoma is the likely explanation for the usual lack of calcification.

Analytical ultrastructural investigation of microliths in salivary glands of cat

Microliths in Araldite-embedded pieces of submandibular and sublingual glands of cat were stained in semithin sections by Methylene Blue and Azure II followed by Basic Fuchsin, and were examined in ultrathin sections by electron-microscopical X-ray microanalysis. Calcium and phosphorus were detected in substantial aggregates of crystals that were stained by Basic Fuchsin and appeared to be hydroxyapatite, but were not detected in granular material that was stained by Methylene Blue and Azure II and appeared to be organic. The polychromatic stain thus appears to be a useful indicator of calcified material. The majority of microliths in acini contained substantial aggregates of crystals, whereas the majority of those in ducts did not. This corresponds to the distribution of the glandular calcium, and suggests that microliths are variously enriched with calcium according to its local level.

Ultrastructural observation of calcification in a pleomorphic adenoma of the parotid gland

A pleomorphic adenoma was examined by electron microscopy. Calcification was found in a lumen and in epithelial cells and consisted of needle-shaped crystals that contained calcium and phosphorus and were probably apatite. Small collections of crystals in the lumen, which were often associated with membranous cellular debris, appeared to form larger calcified masses by fusion. Collections of crystals were seen in vacuoles in adluminal cells. The calcification in the lumen may have started on membranous cellular debris, and that in the adluminal cells may have arisen either by endocytosis of luminal material or by autophagocytosis. The calcification appears to relate to the old age of the tumor.

The spontaneous disappearance of breast calcification

The spontaneous disappearance of both coarse and fine calcification in the breast was noted in 11 cases who presented either with breast symptoms or to a screening unit. While fine and coarse calcification occur in benign disease, the spontaneous regression of this finding appears not to have been reported previously.

Different types of microcalcifications observed in breast pathology. Correlations with histopathological diagnosis and radiological examination of operative specimens

Microcalcifications taken from 50 systematized mammary excisions were submitted to light microscopic and scanning electron microscope analysis. Microprobe and x-ray diffraction analyses were also performed. Two main types were observed: Type I microcalcifications composed of weddellite crystals. They were observed in benign breast lesions only (11 cases out of 21) or, in lobular carcinomas in situ (L.C.I.S.) of the breast (5 cases out of 6). They were not seen in 3 cases of intraductal carcinoma (I.D.C.) nor in infiltrating (I.C.) carcinomas (20 cases). Type II microcalcifications, non-cristalline in nature, composed of calcium, phosphate, hydroxyapatite or of phosphorus and calcium associated with other elements, were observed in benign lesions (10 cases out of 21) and in all cases of infiltrating carcinomas. The microcalcifications observed on mammography were also found on the radiographs of systematised mammary excisions from the lesion or from its immediate vicinity, but only when using the appropriate technique. Microcalcifications are therefore an excellent marker of breast lesions but they cannot be simply divided into "benign" or "malignant" types. Nevertheless, the presence of a visible crystalline structure on the radiograph of the specimen argues in favour of a benign breast lesion or of a lobular carcinoma in situ.

Calcification of non-collagenous matrix in human gingiva: a light and electron microscopic study

Tissue samples obtained from human gingiva with soft tissue calcification were processed for light and transmission electron microscopy. The stroma in these specimens revealed numerous foci of calcification in a matrix that consisted of closely packed branching microfibrils, 12 nm in diameter and a maximum of 2.5 micron in length. Calcospherites, 0.25-1.11 micron in diameter, were present within the matrix. They were constructed of needle-like units shown by high resolution electron microscopy and energy dispersive X-ray microanalysis to be apatite. Larger calcified masses were composed of calcospherites which were fused together. Matrix vesicles or other forms of membraneous material could not be found. The relationship between the mineral and non-collagenous microfibrils may suggest a role for the latter in the onset of calcification in this ectopic site.

Structure and composition of microcalcifications in benign and malignant lesions of the breast: study by light microscopy, transmission and scanning electron microscopy, microprobe analysis, and X-ray diffraction

Microcalcifications previously located by radiography were extracted from 25 fresh specimens obtained from patients who had undergone tumorectomy or systematized mammary exeresis. Two principal types of microcalcifications were distinguished: Type I microcalcifications were amber in color and generally crystalline on scanning electron microscopy, with only one calcium peak on microprobe analysis; x-ray diffraction revealed that weddellite was involved. Type II microcalcifications were whitish, nonbirefringent under polarized light, and generally ovoid or fusiform, with two peaks, one calcium and the other phosphorus, on microprobe analysis; these microcalcifications were composed of calcium phosphate, the most characteristic form of which is hydroxyapatite, in the form of needles arranged in rosettes on transmission electron microscopy. Type I microcalcifications were observed in four of eight benign breast lesions, in two of three in situ lobular carcinomas, and in no intraductal adenocarcinomas or infiltrating carcinomas. Type II microcalcifications were present in all infiltrating carcinomas and intraductal adenocarcinomas; they were also found in benign lesions (four of eight) and even associated with type I microcalcifications in one in situ lobular carcinoma. There are, therefore, no "benign" or "malignant" microcalcifications; however, the presence of weddellite is a strong indication that a lesion is benign or, at most, an in situ lobular carcinoma.

Intraluminal calcium hydroxyapatite crystals in breast carcinoma: an ultrastructural study

Sixty-three breast carcinomas were examined by electron microscopy to determine the frequency of calcium hydroxyapatite (apatite) within tumor lumina. Twenty-one adenocarcinomas contained apatite in intracytoplasmic and/or intercellular lumina. Well-differentiated tumors exhibited a higher incidence of apatite (44%), while only 20% of the poorly differentiated tumors contained apatite (gamma = +.22). There was no apparent correlation between the presence of apatite and a positive estrogen receptor assay. Ninety-eight adenocarcinomas of other than breast origin (previously processed for electron microscopy) were examined, revealing 2 cases containing apatite in the appropriate locations. The tissue of origin in one case was determined to be ovarian, while the origin of the second case remains undetermined. The ultrastructural finding of apatite in lumina of adenocarcinoma appears to be unusual in that it has only been observed in breast carcinomas and certain ovarian tumors. The presence of apatite within the lumen in addition to other characteristics of an adenocarcinoma may suggest the breast as the primary site.

Microcalcifications in benign breast diseases. A histological and histochemical study

A hundred cases of fibroadenomas and 300 cases of benign breast diseases were studied without previous roentgenographic examination of the specimens. Microcalcifications were found in 19% of the fibroadenomas, in 26% of the cases of "fibrous disease" and in 57% of the cases of fibrocystic disease. Benign microcalcifications were not found in normal mammary tissue. They were steadily associated with metaplastic epithelial cells and with their abnormal secretions. Two basic types of microcalcifications were encountered: The granular microcalcifications with a predominately intracellular location and the homogeneous (with or without concentric rings) mainly associated with secreted materials. Microcalcifications were associated with metaplastic epithelial cells of the small eosinophilic variety and with their secretions, with the foam cells and with materials secreted by the apocrine cells. A common histochemical feature in cells or matrixes containing microcalcifications was the presence of compound lipids. The possible relationship of benign breast microcalcifications to the calcifications of other tissues, in connection with their association with lipids is discussed.

The role of mammography in the evaluation of advanced breast cancer treated by initial endocrine therapy

Fifty-five patients with locally advanced breast cancer treated with initial endocrine therapy have been followed up for periods of between 6 and 64 months (median 17 months) with regular clinical and radiological examination. The aim of the study was to evaluate the role of mammography in initial assessment, and subsequent follow-up. Fifty patients were available for evaluation and were classified by clinical, and by mammographic data independently. The clinical assessment, using UICC criteria of response, estimated 36 patients (72 per cent) as responders (complete response, partial response and no change). Mammographic assessment of response, using 8 radiological features of malignancy, agreed with the clinical estimate in 48 per cent of cases and 32 patients (64 per cent) were assessed as responders. Where clinical and mammographic assessment differed, it was usually due either to a smaller radiological reduction in tumour size, or mammography demonstrating features of progressive disease not observed clinically. Two other mammographic features studied were of prognostic significance. In 70 per cent of the responders in which microcalcifications were present, they became reduced in number but increased in size, a change not seen in non-responders. A curvilinear band, or 'rainbow sign', is described which is an early sign of localized skin infiltration and was associated with a poor prognosis.

X-ray calcifications as the only basis for breast biopsy

Two hundred fifty-one consecutive patients were treated between 1964 and 1982 with mammographic calcifications as the only reason for breast biopsy. Patients with either clinical or x-ray findings other than calcifications were excluded. A correlation of the x-ray, pathology, and clinical experience is the basis of this report. Specimen radiography with paraffin section histology (i.e., no frozen section) was performed on all biopsy material. The procedure of specimen radiography that was utilized is described. A team approach involving radiologists, pathologists, and surgeons has been essential both to confirm excision of the calcifications and localize them for pathology study. Carcinoma was found in 45 patients (17%). A retrospective study of the calcifications was also undertaken to determine characteristics that would permit definitive radiographic diagnosis of benign or malignant disease.

The ultrastructure of medullary carcinoma of the breast

Three cases of medullary carcinoma complying with strictly defined criteria have been examined by electron microscopy. These carcinomas are characterised by the presence of light and dark tumour cells which exhibit prominent organelles and well-developed Golgi complexes but lack secretory activity. The essential stromal cellular infiltrate of macrophages, lymphocytes and plasma cells contains macrophage-lymphocyte clusters suggesting the existence of an immune response. Also present in the stroma are blood vessels lined by high-endothelial cells of the type said to facilitate lymphocyte migration. It is suggested that light and dark tumour cells with well-developed organelles but absent secretory activity, macrophage-lymphocyte clusters and stromal high-endothelial venules represent specific ultrastructure features of typical medullary carcinoma associated with good prognosis.

Calcium deposition in human pituitary adenomas studied by histology, electron microscopy, electron diffraction and X-ray spectrometry

The incidence and morphogenesis of calcification were investigated by histology, electron microscopy, electron diffraction and X-ray spectrometry in 312 surgically removed human pituitary adenomas. By light microscopy the incidence of calcification was 9%. The calcium deposits were evident in several adenoma types, but were most frequent and extensive in prolactin-producing adenomas. Histologically calcium deposits represented amorphous precipitates and psammoma bodies staining with hematoxylin, the von Kossa technique and alizarin red. By electron microscopy, calcified deposits were noted in the cytoplasm of adenoma cells and extracellular space. Electron diffraction and X-ray spectrometry of intracellular precipitates as well as psammoma bodies showed the presence of phosphate, calcium and organically bound sulphur with a ratio of 3.5:5:2, indicating that they contained calcium hydroxyapatite. Present findings provide evidence that mitochondria with microcrystal deposition of calcium represent the primary sites of calcification.

Duodenal carcinoid (apudoma) with psammoma bodies: a light and electron microscopic study

An extremely rare case of psammomatous calcification in a nonfunctioning duodenal carcinoid tumor was studied by light and electron microscopy. The psammoma bodies were found most frequently within the lumina of the neoplastic glands. The ultrastructural features of the psammoma bodies were the marginal needle-shaped crystals and a coarse granular matrix in which a few organelles were embedded. The psammoma bodies appeared to be occasionally intracytoplasmic in position, showing no distinct limiting cytoplasmic membrane. Electron probe x-ray microanalysis revealed that the needle-shaped crystals contained calcium. The mechanism by which the psammoma bodies are formed has not been clearly explained. The above findings support the view that the psammoma bodies may occur initially in the cytoplasm of the tumor cells, followed by their release probably in a way of active excretion.

The relationship between microcalcification and in situ carcinoma of the breast

The relationship of microcalcification to lobulo-ductal dysplasia and non-invasive carcinoma was studied in 20 women with in situ carcinoma of the breast. All had microcalcification on the mammogram and in half there was also mammographic evidence of disruption of the breast structure. Three-quarters of the women presented with breast symptoms. Multifocal carcinoma was found in seven patients and the histology suggested that not all foci may progess to extensive duct infiltration or invasion. Calcification was found to occur both in carcinoma and in adjacent benign breast lesions and in three cases no evidence of calcification was found in the carcinoma, but was present in adjacent epitheliosis. The origin and distribution of microcalcification appears to be the same in epithelial hyperplasia, non-invasive carcinoma and invasive carcinoma and there may be a relationship between the amount of calcification and the activity of the epithelial cells. Microcalcification is not specific to breast cancer, but is a product of increased cellular activity in the lobulo-ductal complex and may be extruded into the surrounding interstitial tissue. This implies that microcalcification on the mammogram, particularly if sparse, demonstrates a high risk area of breast rather than a certainty of the presence of carcinoma.