GDP-D-mannose 3,5-epimerase (GME) plays a key role at the intersection of ascorbate and non-cellulosic cell-wall biosynthesis in tomato

The GDP-D-mannose 3,5-epimerase (GME, EC 5.1.3.18), which converts GDP-d-mannose to GDP-l-galactose, is generally considered to be a central enzyme of the major ascorbate biosynthesis pathway in higher plants, but experimental evidence for its role in planta is lacking. Using transgenic tomato lines that were RNAi-silenced for GME, we confirmed that GME does indeed play a key role in the regulation of ascorbate biosynthesis in plants. In addition, the transgenic tomato lines exhibited growth defects affecting both cell division and cell expansion. A further remarkable feature of the transgenic plants was their fragility and loss of fruit firmness. Analysis of the cell-wall composition of leaves and developing fruit revealed that the cell-wall monosaccharide content was altered in the transgenic lines, especially those directly linked to GME activity, such as mannose and galactose. In agreement with this, immunocytochemical analyses showed an increase of mannan labelling in stem and fruit walls and of rhamnogalacturonan labelling in the stem alone. The results of MALDI-TOF fingerprinting of mannanase cleavage products of the cell wall suggested synthesis of specific mannan structures with modified degrees of substitution by acetate in the transgenic lines. When considered together, these findings indicate an intimate linkage between ascorbate and non-cellulosic cell-wall polysaccharide biosynthesis in plants, a fact that helps to explain the common factors in seemingly unrelated traits such as fruit firmness and ascorbate content.

An integrative genomics approach for deciphering the complex interactions between ascorbate metabolism and fruit growth and composition in tomato

Very few reports have studied the interactions between ascorbate and fruit metabolism. In order to get insights into the complex relationships between ascorbate biosynthesis/recycling and other metabolic pathways in the fruit, we undertook a fruit systems biology approach. To this end, we have produced tomato transgenic lines altered in ascorbate content and redox ratio by RNAi-targeting several key enzymes involved in ascorbate biosynthesis (2 enzymes) and recycling (2 enzymes). In the VTC (ViTamin C) Fruit project, we then generated phenotypic and genomic (transcriptome, proteome, metabolome) data from wild type and mutant tomato fruit at two stages of fruit development, and developed or implemented statistical and bioinformatic tools as a web application (named VTC Tool box) necessary to store, analyse and integrate experimental data in tomato. By using Kohonen's self-organizing maps (SOMs) to cluster the biological data, pair-wise Pearson correlation analyses and simultaneous visualization of transcript/protein and metabolites (MapMan), this approach allowed us to uncover major relationships between ascorbate and other metabolic pathways.

[Adenocarcinomas of nasal cavities and paranasal sinuses: Diagnostic pitfalls in sinonasal glandular lesions]

Among primitive adenocarcinoma of nasal cavity and paranasal sinus, the 2005 WHO classification distinguishes two main categories: intestinal type adenocarcinoma (ITAC) and low-grade non-intestinal adenocarcinoma, entities with different clinical and epidemiological characteristics. Low-grade adenocarcinoma shows a respiratory type phenotype (CK20-/CK7+/CDX2-/villin-) and ITACs, an intestinal type profile (CK20+/CK7-/CDX2+/villin+). Because of histological, ultrastructural and phenotypical similarities between ITAC and colorectal adenocarcinomas, several studies have discussed a possible common pathway in carcinogenesis. But the review of literature shows conflicting results, suggesting different pathways of pathogenesis. Differential diagnoses of sinonasal intestinal-type adenocarcinoma are mainly respiratory epithelial adenomatoid hamartomas, inverted schneiderian papillomas, salivary glands-type carcinoma and more rarely metastasis of adenocarcinoma.

Prolonged root hypoxia induces ammonium accumulation and decreases the nutritional quality of tomato fruits

Here we examined the effects of root hypoxia (1-2% oxygen) on the physiology of the plant and on the biochemical composition of fruits in tomato (Solanum lycopersicum cv. Micro-Tom) plants submitted to gradual root hypoxia at first flower anthesis. Root hypoxia enhanced nitrate absorption with a concomitant release of nitrite and ammonium into the medium, a reduction of leaf photosynthetic activity and chlorophyll content, and an acceleration of fruit maturation, but did not affect final fruit size. Quantitative metabolic profiling of mature pericarp extracts by (1)H NMR showed that levels of major metabolites including sugars, organic acids and amino acids were not modified. However, ammonium concentration increased dramatically in fruit flesh, and ascorbate and lycopene concentrations decreased. Our data indicate that the unfavorable effects of root hypoxia on fruit quality cannot be explained by two of the well-known effects of root hypoxia on the plant, namely a decrease in photosynthesis or an excess in ethylene production, but may instead result from disturbances in the supply of either growth regulators or ammonium, by the roots.

Calcified glomus tumor of the shoulder. A case report

The authors report a case of calcified glomus tumor of the shoulder in a 54-year-old woman. The nonspecific clinical findings and the noncharacteristic imaging results made diagnosis of this tumor impossible before surgery. The diagnosis was confirmed by a biopsy. The outcome after surgical resection was excellent.

Silencing of the mitochondrial ascorbate synthesizing enzyme L-galactono-1,4-lactone dehydrogenase affects plant and fruit development in tomato

L-Galactono-1,4-lactone dehydrogenase (EC 1.3.2.3) catalyzes the last step in the main pathway of vitamin C (L-ascorbic acid) biosynthesis in higher plants. In this study, we first characterized the spatial and temporal expression of SlGalLDH in several organs of tomato (Solanum lycopersicum) plants in parallel with the ascorbate content. P(35S):Slgalldh(RNAi) silenced transgenic tomato lines were then generated using an RNAi strategy to evaluate the effect of any resulting modification of the ascorbate pool on plant and fruit development. In all P(35S):Slgalldh(RNAi) plants with reduced SlGalLDH transcript and activity, plant growth rate was decreased. Plants displaying the most severe effects (dwarf plants with no fruit) were excluded from further analysis. The most affected lines studied exhibited up to an 80% reduction in SlGalLDH activity and showed a strong reduction in leaf and fruit size, mainly as a consequence of reduced cell expansion. This was accompanied by significant changes in mitochondrial function and altered ascorbate redox state despite the fact that the total ascorbate content remained unchanged. By using a combination of transcriptomic and metabolomic approaches, we further demonstrated that several primary, like the tricarboxylic acid cycle, as well as secondary metabolic pathways related to stress response were modified in leaves and fruit of P(35S):Slgalldh(RNAi) plants. When taken together, this work confirms the complexity of ascorbate regulation and its link with plant metabolism. Moreover, it strongly suggests that, in addition to ascorbate synthesis, GalLDH could play an important role in the regulation of cell growth-related processes in plants.

Primary amenorrhea in a 46,XY adolescent girl with partial gonadal dysgenesis: identification of a new SRY gene mutation

OBJECTIVE

To determine the genetic cause of primary amenorrhea in a 46,XY adolescent girl.

DESIGN

Case report.

SETTING

Pediatric endocrinology and gynecologic unit of an academic hospital.

PATIENT(S)

A 16-year-old adolescent referred for primary amenorrhea.

INTERVENTION(S)

Endocrine and surgical investigation, SRY mutational analysis.

MAIN OUTCOME MEASURE(S)

Plasma gonadotropin levels, estradiol and testosterone levels, and pathologic findings.

RESULT(S)

We report a new mutation of the SRY gene in a 46,XY sex-reversed patient. We observed two unusual features. First, partial pubertal development has rarely been described in association with SRY gene mutation. Second, the location of the mutation was in the HMG box region of the SRY gene, in contrast to the other partial cases of 46,XY gonadal dysgenesis. In addition, the presence of a gonadoblastoma underlines the necessity of removing the gonads quickly in 46,XY sex-reversal cases, and raises several questions about the role of the SRY gene in the development of such tumors.

CONCLUSION(S)

Partial pubertal development in a 46,XY sex-reversed patient does not exclude SRY gene mutation.

Extinction of FOXL2 expression in aggressive ovarian granulosa cell tumors in children

OBJECTIVE

In the female gonad, FOXL2 is a key factor for proper differentiation of granulosa cells (GC) during folliculogenesis and its expression persists in the ovary after birth. The aim of this multicentric nationwide study was to determine whether FOXL2 expression varies during tumoral proliferation of GC cells in juvenile ovarian GC tumors (OGCT).

DESIGN

Nationwide retrospective study.

SETTING

University Hospital of Montpellier, Department of Hormonology.

PATIENT(S)

Between 1994 and 2004, 26 patients with juvenile OGCT were reported in the TGM95 database of the French Society for Childhood Cancer (SFCE) and from eight pediatric endocrinology centers. Immunohistochemistry was performed using an anti-FOXL2 antibody.

INTERVENTION(S)

Immunohistochemistry studies of FOXL2 on OGCT slides.

MAIN OUTCOME MEASURE(S)

Level of FOXL2 expression within the tumor, International Federation of Gynecology and Obstetrics classification, and tumor recurrences.

RESULT(S)

FOXL2 expression was absent in the GC of 10 patients and was markedly reduced in the cells of 4 patients. Precocious pseudopuberty was more frequently the revealing symptom in the children with conserved FOXL2 expression. Patients with no or reduced expression of FOXL2 more frequently exhibited associated hemorrhagic ascites, higher mitotic activity in the tumor, and significantly more advanced oncologic staging. All patients requiring complementary treatment (n = 7; chemotherapy or complementary surgery) had reduced expression of FOXL2 in the tumor. All recurring OGCT exhibited a complete extinction of FOXL2 expression (n = 3).

CONCLUSION(S)

These results show that FOXL2 is not expressed or is underexpressed in juvenile OGCT with an aggressive pattern of progression, and it thus may be a prognostic factor for these tumors.

Candidate genes and quantitative trait loci affecting fruit ascorbic acid content in three tomato populations

Fresh fruit and vegetables are a major source of ascorbic acid (vitamin C), an important antioxidant for the human diet and also for plants. Ascorbic acid content in fruit exhibits a quantitative inheritance. Quantitative trait loci (QTL) for ascorbic acid content have been mapped in three tomato populations derived from crosses between cultivated tomato varieties (Solanum lycopersicum accessions) and three related wild species or subspecies. The first population consists of a set of introgression lines derived from Solanum pennellii, each containing a unique fragment of the wild species genome. The second population is an advanced backcross population derived from a cross between a cultivated tomato and a Solanum habrochaites (formerly Lycopersicum hirsutum) accession. The third population is a recombinant inbred line population derived from the cross between a cherry tomato line and a large fruited line. Common regions controlling ascorbic acid content have been identified on chromosomes 2, 8, 9, 10, and 12. In general, the wild alleles increased ascorbic acid content, but some improvement could also be provided by S. lycopersicum. Most QTLs appeared relatively stable over years and in different environments. Mapping of candidate genes involved in the metabolism of ascorbic acid has revealed a few colocations between genes and QTLs, notably in the case of a monodehydroascorbate reductase gene and a QTL present in two of the populations on chromosome 9 (bin 9-D), and a previously mapped GDP-mannose epimerase and a QTL on chromosome 9 (bin 9-J).

Pyruvate modifies glycolytic and oxidative metabolism of rat embryonic spinal cord astrocyte cell lines and prevents their spontaneous transformation

This study aimed to provide detailed data on mitochondrial respiration of normal astrocyte cell lines derived from rat embryonic spinal cord. Astrocytes in early passages (EP), cultured without pyruvate for more than 35 passages, defined here as late passages (LP), undergo spontaneous transformation. To study initial steps in cell transformation, EP data were compared with those of LP cells. LP cells had reduced glycolysis, fewer mitochondria and extremely low oxidative rates, resulting from a dysfunction of complexes I and II + III of the respiratory chain. Treatment of EP cells with pyruvate until they were, by definition, LP cultures prevented transformation of these cells. Pyruvate-treated EP cells had more mitochondria than normal cells but slightly lower respiratory rates. The increase of mitochondrial content thus appears to act as a compensatory effect to maintain oxidative phosphorylation in these LP 'non-transformed' cells, in which mitochondrial function is reduced. However, pyruvate treatment of transformed LP cells during additional passages did not significantly restore their oxidative metabolism. These data highlight changes accompanying spontaneous astrocyte transformation and suggest potential targets for the control of astrocyte proliferation and reaction to various insults to the central nervous system.

Activating mutations of Gsalpha in kidney cancer

PURPOSE

Heterotrimeric G proteins are signal transduction proteins coupled to hormone receptors that activate intracellular second messenger systems, mainly cyclic adenosine monophosphate mediated protein kinase. Recent studies indicate that G proteins may have a major role in oncogenesis as well as in tumor invasiveness and cell proliferation. The involvement of G proteins was formerly thought to be limited to hormonal signal transduction. Activating Gsalpha mutations have been reported in tumors arising only from highly specialized endocrine tissue, such as pituitary adenomas, toxic thyroid adenomas and differentiated thyroid carcinomas, but never in other nonendocrine tumors. We hypothesized that a constitutive activation of this pathway, that is activated Gsalpha and inhibited Gialpha, could be implicated in kidney cancers. We searched for alterations on the Gsalpha gene GNAS and the Gialpha gene in renal cell carcinoma.

MATERIALS AND METHODS

Using nested polymerase chain reaction, enzyme digestions, laser microdissection and direct sequencing we looked for activating mutations on GNAS codons 201 and 227, and inhibiting mutations on the Gialpha gene in 30 consecutive patients with clear cell renal cell carcinoma between January 2003 and January 2004.

RESULTS

Somatic (tumor specific) activating mutations of Gsalpha were present in a significant proportion of human clear cell renal cell carcinomas. Activating mutations were identified in 5 of the 30 patient DNA preparations (16.6%) with a substitution of arginine 201 by cysteine in 3 and histidine in 2.

CONCLUSIONS

These findings suggest the implication of this pathway in human oncogenesis. It may provide a potential therapeutic approach to these frequent and aggressive tumors.

Activating mutations of the stimulatory g protein in juvenile ovarian granulosa cell tumors: a new prognostic factor?

CONTEXT

Conflicting data have been reported regarding the presence of a constitutive activation of Galphas in ovarian granulosa cell tumors (OGCTs). Although the precise role of this mutation in the transformation of ovarian cells into malignant cells remains debatable, it has been demonstrated in other tissues that the rate of cell proliferation and invasiveness can be influenced by the gsp oncogene.

OBJECTIVE

The objective of this study was to determine whether activating mutations of Galphas or Galphai are present in juvenile OGCTs and, if so, whether these mutations are significant prognostic factors.

DESIGN AND SETTING

This was a multicentric nationwide study.

PATIENTS AND METHODS

Thirty children with juvenile OGCT were included from the malignant germinal tumor protocol of the French Society for Childhood Cancer. Genetic studies of the tumoral DNA used nested PCR, laser microdissection, and direct sequencing.

RESULTS

Galphas-activating mutations in hot spot position 201 were found in nine patients (30%). Laser microdissection confirmed that mutations R201C and R201H were exclusively localized in the tumoral granulosa cells and were absent in the ovarian stroma. Patients with a hyperactivated Galphas exhibited a significantly more advanced tumor (P < 0.05) because seven of them (77.7%) were staged as Ic or had had a recurrence. Galphai did not exhibit any mutation.

CONCLUSIONS

Activating mutations of Galphas are present in 30% of juvenile OGCTs. The gsp oncogene, which is known to be implicated in cell proliferation and tumoral invasiveness, can be considered as a new prognostic factor of these tumors.

[Langherans' cell histiocytosis: a case report]

Langherans' cell histiocytosis is rare in adults. It should be considered in patients with lytic osseous lesions with sclerotic rim especially when involvement of adjacent soft tissues is present.

The expression of cell proliferation-related genes in early developing flowers is affected by a fruit load reduction in tomato plants

Changes in photoassimilate partitioning between source and sink organs significantly affect fruit development and size. In this study, a comparison was made of tomato plants (Solanum lycopersicum L.) grown under a low fruit load (one fruit per truss, L1 plants) and under a standard fruit load (five fruits per truss, L5 plants), at morphological, biochemical, and molecular levels. Fruit load reduction resulted in increased photoassimilate availability in the plant and in increased growth rates in all plant organs analysed (root, stem, leaf, flower, and fruit). Larger flower and fruit size in L1 plants were correlated with higher cell number in the pre-anthesis ovary. This was probably due to the acceleration of the flower growth rate since other flower developmental parameters (schedule and time-course) remained otherwise unaffected. Using RT-PCR, it was shown that the transcript levels of CYCB2;1 (cyclin) and CDKB2;1 (cyclin-dependent kinase), two mitosis-specific genes, strongly increased early in developing flower buds. Remarkably, the transcript abundance of CYCD3;1, a D-type cyclin potentially involved in cell cycle regulation in response to mitogenic signals, also increased by more than 5-fold at very early stages of L1 flower development. By contrast, transcripts from fw2.2, a putative negative regulator of cell division in tomato fruit, strongly decreased in developing flower bud, as confirmed by in situ hybridization studies. Taken together, these results suggest that changes in carbohydrate partitioning could control fruit size through the regulation of cell proliferation-related genes at very early stages of flower development.

[How can the diagnostic value of head and neck biopsies be increased in Wegener's granulomatosis: a clinicopathologic study of 49 biopsies in 21 patients]

Head and neck biopsies usually have a low diagnostic value in Wegener's granulomatosis (WG). On the basis of 49 biopsies obtained from 21 WG patients at diagnosis from various sites, i.e. nose (29), paranasal sinus (7), oral cavity (4), larynx (4), conjunctiva (3) and external ear (2), we described the suggestive histological features and studied the diagnostic potential of the biopsy size, anaesthesia method (general (GA) or local (LA)), anatomic region of the biopsy, number of sections, and presenting macroscopic manifestations. Associated granulomatous inflammation (scattered giant cells, 28.5% of biopsies; poorly-formed granulomas, 28.5%), necrosis (neutrophilic microabscesses, 16.3%; geographic necrosis, 18.3%), angiitis (leukocytoclastic, 10%; necrotizing, 12%; and granulomatous, 6%) which confirmed the diagnosis were only present in 18.3% of the biopsies (28.5% of the patients). We think it is possible to propose a "WG-compatible" diagnosis when at least one of these histological features is present (24.5% of biopsies, 26% of patients in our study). We found that it was always better to perform biopsies targeted on macroscopic lesions. When there was no lesion, samples from paranasal sinuses obtained under GA had the highest diagnostic value in the head and neck region, whereas 90% of nasal systematic biopsies performed under LA were nonspecific. Moreover, we demonstrated that performing two further sections increased the sensitivity of histological examination by 7%.

Changes in transcriptional profiles are associated with early fruit tissue specialization in tomato

The cell expansion phase contributes in determining the major characteristics of a fleshy fruit and represents two-thirds of the total fruit development in tomato (Solanum lycopersicum). So far, it has received very little attention. To evaluate the interest of a genomic scale approach, we performed an initial sequencing of approximately 1,200 cell expansion stage-related sequence tags from tomato fruit at 8, 12, and 15 d post anthesis. Interestingly, up to approximately 35% of the expressed sequence tags showed no homology with available tomato expressed sequence tags and up to approximately 21% with any known gene. Microarrays spotted with expansion phase-related cDNAs and other fruit cDNAs involved in various developmental processes were used (1) to profile gene expression in developing fruit and other plant organs and (2) to compare two growing fruit tissues engaged mostly in cell division (exocarp) or in cell expansion (locular tissue surrounding the seeds). Reverse transcription-polymerase chain reaction analysis was further used to confirm microarray results and to specify expression profiles of selected genes (24) in various tissues from expanding fruit. The wide range of genes expressed in the exocarp is consistent with a protective function and with a high metabolic activity of this tissue. In addition, our data show that the expansion of locular cells is concomitant with the expression of genes controlling water flow, organic acid synthesis, sugar storage, and photosynthesis and suggest that hormones (auxin and gibberellin) regulate this process. The data presented provide a basis for tissue-specific analyses of gene function in growing tomato fruit.

Stereotactic coregistration of 201Tl SPECT and MRI applied to brain tumor biopsies

The aim of the present study was to determine the clinical feasibility of integration of stereotactic SPECT (sSPECT) with 201Tl in the stereotactic MRI (sMRI)-based planning of brain tumor biopsy. Furthermore, the predictive value of the integrated techniques was analyzed by comparison with the corresponding histologically determined metabolic activity.

METHODS

Ten patients underwent combined 201Tl SPECT- and MRI-guided stereotactic biopsy of intracranial lesions according to a previously described technique. An area of abnormal 201Tl uptake was used to guide the stereotactic biopsy trajectory. Several samples were taken along the trajectory above and beneath the target. An extensive histologic diagnosis (tumor grade, mitotic index [MI], and Ki67 index) and the 201Tl index were obtained for all samples and compared statistically.

RESULTS

Combined 201Tl sSPECT- and sMRI-guided biopsy could be performed on all patients. Ki67 index, MI, and tumor grade correlated significantly. The correlations between MI or Ki67 index and 201Tl index were not significant (0.18 and 0.09, respectively). A trend to significance existed between tumor grade and 201Tl index (R = 0.31; P = 0.06). Mean 201Tl index for grade III tumors (3.27 +/- 1.89 [SD]) was significantly different from that for grade IV tumors (4.34 +/- 1.29). The sample position on the trajectory correlated with the MI (R = 0.39; P = 0.01). In 4 of the 10 patients, a variation in tumor grade could be observed along the trajectory. In all patients, the highest proliferative activity was within 5-10 mm of the target.

CONCLUSION

These results support the view that 201Tl SPECT may contribute to the successful management of brain tumor patients requiring stereotactic biopsy, without causing a significant increase in discomfort or morbidity. The development of similar techniques integrating sSPECT data in the planning of stereotactic biopsy should be considered by centers performing stereotactic surgery and having access to SPECT technology. In the long term, this technique could become a support for focused gene therapy and cell transfer.

Tumeur du pied et douleurs diffuses : un cas d’ostéomalacie oncogénique

Oncogenic osteomalacia is a rare clinicopathologic entity, linked to a mesenchymal tumor which overexpresses a hypophosphatemic factor, supposed to be the FGF-23. To date, about 100 cases have been published. We report the case of a 40-year-old man who presented an osteomalacic syndrome with no classical etiological diagnosis. The discovery of a subcutaneous tumor of the right foot and a high serum level of FGF-23 suggested the diagnosis of oncogenic osteomalacia. Surgical removal of the tumor resulted in complete reversal of the clinical and biochemical defects. Pathologic examination revealed spindle cells associated with osteoclast-like giant cells, embedded within a myxoid matrix which showed floculent calcification. These observations were compatible with the features of PMTMCT (Phosphaturic mesenchymal tumor mixed connective tissue variant).

A nationwide study of granulosa cell tumors in pre- and postpubertal girls: missed diagnosis of endocrine manifestations worsens prognosis

BACKGROUND

There are very few data on the natural history of ovarian granulosa cell tumors (OGCT) in children. The aim of this study was to determine whether early recognition and diagnosis of the initial endocrine signs could improve the outcome of these tumors.

METHODS

In a nationwide study from 1990 to 2004, we analyzed the clinical, biological and pathologic data from 40 pre- and postpubertal girls presenting an OGCT.

RESULTS

1. Among the prepubertal girls (n = 29), 17 OGCTs were diagnosed on the basis of precocious pseudopuberty. None of the 17 girls had a peritoneal spread of the tumor (100% FIGO stage Ia). Diagnosis based on a tumoral or acute abdomen (12 cases) was associated with frequent intraperitoneal ruptures of the tumor (50%) and a risk of relapse (2 cases). Of the eight girls who had had a misdiagnosed precocious pseudopuberty, five had a pre- or perioperative tumoral rupture. 2. Among the postpubertal girls (n = 11), endocrine manifestations such as secondary amenorrhea or virilization had been underevaluated in three of them and the diagnosis was established from a tumoral abdomen. This clinical presentation was associated with frequent ruptures of the mass in the peritoneum (80%) and a higher risk of recurrence (30%). 3. A delayed diagnosis of OGCT despite previous endocrine signs (11 cases; 8 pre- and 3 postpubertal) was associated with a high risk of pre- or peri-operative peritoneal tumor spreading (70% FIGO stage Ic or IIc, p <0.05). The mean delay for diagnosis ranged from 3 to 11 months.

CONCLUSION

This study highlights the critical role of early diagnosis of OGCT in pre- and postpubertal girls, particularly at the first seemingly banal signs of endocrine disorder. Peritoneal spread of the tumor may thereby be prevented, which improves the prognosis.

Des cancers du sein sans signe en mammographie : quand et pourquoi ?

Breast carcinomas with false negative mammogram correspond to carcinomas diagnosed with means other than mammogram when the mammogram, at the time of diagnosis, showed no significant abnormality. The rate of false mammogram is difficult to ascertain because few studies have been published on this subject. The absence of mammographic abnormality is related to histopathological characteristics of the tumor and mammographic features of the patient's breast tissue. The small size of the tumor, the lack of microcalcifications often due to tumor necrosis and the absence of any significant associated desmoplastic reaction are the main histopathological factors encountered, particularly for dense breasts.