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3.
Pathologica ; 110(1): 5-11, 2018 Mar.
Article in English | MEDLINE | ID: mdl-30259909

ABSTRACT

Lung cancer is the most frequent human malignancy and the principal cause of cancer-related death worldwide. Adenocarcinoma is now the main histologic type, accounting for almost half of all the cases. The 2015 World Health Organization has adopted the classification recently developed by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society. This new adenocarcinoma classification has incorporated up-to-date advances in radiological, molecular and oncological knowledge, providing univocal diagnostic criteria and terminology. For resection specimens, new entities have been defined such as adenocarcinoma in situ and minimally invasive adenocarcinoma to designate adenocarcinomas, mostly nonmucinous and ≤ 3 cm in size, with either pure lepidic growth or predominant lepidic growth with ≤ 5 mm invasion, respectively. For invasive adenocarcinoma, the new classification has introduced histological subtyping according to the predominant pattern of growth of the neoplastic cells: lepidic (formerly non mucinous brochioloalveolar adenocarcinoma), acinar, papillary, micropapillary, and solid. Of note, micropapillary pattern is a brand new histologic subtype. In addition, four variants of invasive adenocarcinoma are recognized, namely invasive mucinous (formerly mucinous brochioloalveolar adenocarcinoma), colloid, fetal, and enteric. Importantly, three variants that were considered in the previous classification have been eliminated, specifically mucinous cystadenocarcinoma, signet ring cell, and clear cell adenocarcinoma. This review presents the changes introduced by the current histological classification of lung adenocarcinoma and its prognostic implications.


Subject(s)
Adenocarcinoma of Lung/classification , Adenocarcinoma, Mucinous/classification , Adenocarcinoma/classification , Lung Neoplasms/classification , Adenocarcinoma/diagnosis , Adenocarcinoma/pathology , Adenocarcinoma of Lung/diagnosis , Adenocarcinoma of Lung/pathology , Adenocarcinoma, Mucinous/diagnosis , Adenocarcinoma, Mucinous/pathology , Humans , Lung Neoplasms/diagnosis , Lung Neoplasms/pathology , Prognosis
4.
Lung Cancer ; 115: 21-27, 2018 01.
Article in English | MEDLINE | ID: mdl-29290257

ABSTRACT

OBJECTIVES: EGFR T790M mutation is the most common mechanism of resistance to first-/second-generation EGFR tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) and could be overcome by third-generation EGFR-TKIs, such as osimertinib. Liquid biopsy, a non-invasive technique used to test the presence of the resistant mutation, may help avoiding tissue re-biopsy. However, analysing only circulating-free DNA, information about other less frequent and coexisting resistance mechanisms may remain unrevealed. MATERIALS AND METHODS: All patients reported in this series participated in the ASTRIS trial, a real world treatment study testing the efficacy of osimertinib (80mg os die) in advanced T790M-positive NSCLC progressed to prior EGFR-TKI. Patients were considered eligible to osimertinib if T790M positive on tissue or plasma samples. In our patients, EGFR molecular testing on blood sample was conducted with digital droplet PCR (ddPCR). RESULTS: We report our experience of five patients treated with osimertinib after T790M detection on liquid biopsy that presented a disease progression at first tumor assessment mediated by SCLC transformation, as evidenced at tissue re-biopsies. All patients showed low ratio T790M/activating mutation in the blood before osimertinib (lower than 0.03). For three patients, EGFR mutational analysis was T790M-negative when re-assessed by using a less sensitive method (therascreen®) on the same liquid biopsy sample analysed by ddPCR before osimertinib therapy. CONCLUSION: Although liquid biopsy is a relevant tool to diagnose T790M presence in NSCLC patients resistant to EGFR-TKI, in case of a low ratio T790M/activating mutation, tissue biopsy should be considered to exclude the presence of SCLC transformation and/or other concomitant resistance mechanisms.


Subject(s)
Antineoplastic Agents/therapeutic use , Carcinoma, Non-Small-Cell Lung/drug therapy , Lung Neoplasms/drug therapy , Mutation/genetics , Piperazines/therapeutic use , Protein Kinase Inhibitors/therapeutic use , Acrylamides , Aged , Aniline Compounds , Biopsy , Carcinoma, Non-Small-Cell Lung/genetics , Cell Transformation, Neoplastic , DNA Mutational Analysis , Drug Resistance, Neoplasm/genetics , ErbB Receptors/genetics , Female , Humans , Lung Neoplasms/genetics , Male , Middle Aged , Neoplasm Staging
5.
Pathologica ; 102(1): 33-5, 2010 Feb.
Article in English | MEDLINE | ID: mdl-20731252

ABSTRACT

Primary bladder adenocarcinoma accounts for 0.5-2% of all malignant bladder tumours. Literature data indicate the bladder as the second most common site of metastatic genitourinary tumours, with the kidney as the most frequent location. Secondary tumours of the bladder account for about 2.3% of all bladder malignancies encountered in surgical specimens. Herein, we describe an adenocarcinoma deeply infiltrating the bladder wall, with no morphologic features of transitional cell carcinoma, in a patient with a previous diagnosis of primary lung adenocarcinoma, mixed subtype. In this case, the use of a limited immunohistochemical panel including napsin A, a recently described highly sensitive marker for lung adenocarcinoma, GATA3 and S100P, two novel markers of urothelial differentiation, was of crucial importance in differentiating between lung adenocarcinoma metastatic to the bladder and primary bladder adenocarcinoma.


Subject(s)
Adenocarcinoma , Aspartic Acid Endopeptidases/metabolism , Biomarkers, Tumor/metabolism , GATA3 Transcription Factor/metabolism , Lung Neoplasms , S100 Proteins/metabolism , Urinary Bladder Neoplasms , Adenocarcinoma/diagnosis , Adenocarcinoma/metabolism , Adenocarcinoma/pathology , Female , Humans , Lung Neoplasms/diagnosis , Lung Neoplasms/pathology , Lung Neoplasms/secondary , Middle Aged , Urinary Bladder Neoplasms/diagnosis , Urinary Bladder Neoplasms/metabolism , Urinary Bladder Neoplasms/pathology
6.
Dig Liver Dis ; 42(1): 20-7, 2010 Jan.
Article in English | MEDLINE | ID: mdl-19497798

ABSTRACT

BACKGROUND: Recent studies have shown that the cyclooxygenase (COX) and the inducible nitric oxide synthase (iNOS) pathways are involved in the development of tumor angiogenesis in human cancers. AIMS: To investigate whether a different pattern of COX-2 and iNOS expression/activity exists within different areas of colorectal tumors and to analyze the relationship between these two enzymes and tumor angiogenesis. METHODS: Microvessel density (MVD) and COX-2, iNOS, vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR-2) protein expression were evaluated at both the invasive front (IF) and the tumor center (TC) in 46 human colorectal cancer specimens. We also investigated the concentration of PGE2 and NO at the same sites. RESULTS: COX-2 and iNOS protein expression and activity were significantly higher within the IF than the TC of the tumor specimens. Similarly, MVD and VEGF/VEGFR-2 expression significantly increased from the TC to the IF. Only COX-2 expression was significantly correlated with MVD and VEGF/VEGFR-2 expression at both the TC and the IF. CONCLUSION: Our study shows a heterogeneous expression of COX-2 and iNOS in colorectal cancer. The up-regulation of COX-2 at the IF parallels an increase in vessel density and VEGF/VEGFR-2 expression, thus supporting the hypothesis that the tumor periphery is the most aggressive portion of a colorectal tumor.


Subject(s)
Colorectal Neoplasms/metabolism , Cyclooxygenase 2/metabolism , Neovascularization, Pathologic/metabolism , Nitric Oxide Synthase Type II/metabolism , Aged , Aged, 80 and over , Colorectal Neoplasms/blood supply , Colorectal Neoplasms/pathology , Female , Humans , Male , Middle Aged , Neoplasm Invasiveness , Up-Regulation , Vascular Endothelial Growth Factor A/metabolism , Vascular Endothelial Growth Factor Receptor-2/metabolism
7.
Thorax ; 63(4): 345-51, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18086752

ABSTRACT

BACKGROUND: Malignant pleural mesothelioma (MPM) is an asbestos related tumour difficult to detect early and treat effectively. Asbestos causes genetic modifications and cell signalling events that favour the resistance of MPM to apoptosis and chemotherapy. Only a small number of patients, approximately 10%, survive more than 3 years. The aim of our study was to assess possible differences within signalling pathways between short term survivors (survival <3 years; STS) and long term survivors (survival >3 years; LTS) of MPM. METHODS: 37 antibodies detecting proteins engaged in cell signalling pathways, enforcing proliferation, antiapoptosis, angiogenesis and other cellular activities were investigated by tissue microarray (TMA) technology. RESULTS: Epidermal growth factor receptor (EGFR) was expressed stronger in LTS whereas platelet derived growth factor receptor (PDGFR) signalling was more abundant in STS. Expression of TIE2/Tek, a receptor for tyrosine kinases involved in angiogenesis, was differentially regulated via PDGFR and thus is more important in STS. Antiapoptosis was upregulated in STS by signal transducer and activator of transcription 1 (STAT1)-survivin and related molecules, but not in LTS. Our study provides novel insights into the regulatory mechanisms of signalling pathways in MPM, which differentially promote tumour growth in LTS and STS. CONCLUSION: We have demonstrated that small scale proteomics can be carried out by powerful linkage of TMA, immunohistochemistry and statistical methods to identify proteins which might be relevant targets for therapeutic intervention.


Subject(s)
Biomarkers, Tumor/metabolism , ErbB Receptors/metabolism , Mesothelioma/pathology , Neoplasm Proteins/metabolism , Pleural Neoplasms/pathology , Receptors, Platelet-Derived Growth Factor/metabolism , Adult , Aged , Cell Communication , Cell Proliferation , Female , Humans , Immunohistochemistry , Male , Mesothelioma/mortality , Microarray Analysis , Middle Aged , Pleural Neoplasms/mortality , Prognosis
8.
Eur J Surg Oncol ; 33(6): 763-8, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17306497

ABSTRACT

BACKGROUND: A retrospective study including all patients with non-small cell lung cancer carcinoma in a population-based registry was performed to characterize gender differences in lung cancer and to analyze the factors influencing prognosis in women. METHODS: We retrieved through the Tuscan Cancer Registry (RTT) archive 2,523 lung tumor cases diagnosed during the period 1996-1998 in the provinces of Florence and Prato, central Italy. We compared the prognosis within 464 non-small lung cancer women and 1,798 men in a population-based case series. The influence of the following variables on postoperative survival were analyzed: age, cell type, pathologic T and N status, site of tumor and type of surgical resection. RESULTS: The age at diagnosis was similar in women and in men. Women were significantly more likely to have adenocarcinoma but less likely to have squamous cell carcinoma compared with men. Fewer pneumonectomies were performed in women than in men. Nevertheless, prognosis was similar in both sexes and type of surgical resection was significant prognostic factor. CONCLUSIONS: Lung cancer was more frequent in men than in women, but overall survival is similar. Differences in lung cancer histology and rate of pneumonectomies were found between men and women.


Subject(s)
Carcinoma, Non-Small-Cell Lung/epidemiology , Lung Neoplasms/epidemiology , Adenocarcinoma/epidemiology , Age Factors , Carcinoma, Adenosquamous/epidemiology , Carcinoma, Squamous Cell/epidemiology , Female , Follow-Up Studies , Humans , Italy/epidemiology , Lymph Node Excision/statistics & numerical data , Male , Middle Aged , Neoplasm Staging , Pneumonectomy/statistics & numerical data , Population Surveillance , Prognosis , Registries , Retrospective Studies , Sex Factors , Survival Rate , Treatment Outcome
9.
Eur Respir J ; 28(6): 1186-9, 2006 Dec.
Article in English | MEDLINE | ID: mdl-16899486

ABSTRACT

Randomised controlled trials for lung cancer screening using high-resolution computed tomography are now underway. In order to allow effective future comparison of the different trials, as well as strengthening conclusions based upon the analysis of larger data sets, uniformity and consistency of pathology diagnosis are essential. The aim of the present study was to determine the effectiveness of the learning process in this difficult area of diagnostic pathology. Eight pathologists received two CD-ROMs, each with digital images of 30 cases. After diagnosing the first series, selected background reading was provided. Kappa (kappa) scores were calculated for each pathologist and category, and were compared to the consensus score. The readings of the first series showed a moderate agreement kappa score: mean+/-sd for category numbers 8 (all eight categories) and 2 were 0.53+/-0.05 and 0.65+/-0.04, respectively. The kappa 2 score distinguished between categories denoting benign and malignant lesions. The second series resulted in a good agreement kappa score: 0.65+/-0.06 for category number 8 and 0.81+/-0.02 for category number 2. In conclusion, this study demonstrates that screen-detected cases pose particular problems for pathologists and that a trained pathology panel serving randomised controlled trials is likely to lead to more consistent and accurate tissue diagnosis.


Subject(s)
Lung Neoplasms/diagnosis , Lung/pathology , Mass Screening , Tomography, X-Ray Computed , Adenocarcinoma/diagnosis , Carcinoma, Large Cell/diagnosis , Carcinoma, Small Cell/diagnosis , Carcinoma, Squamous Cell/diagnosis , Histological Techniques/methods , Histological Techniques/standards , Humans , Lung Neoplasms/classification , Neoplasm Staging , Observer Variation , Pathology, Clinical , Reproducibility of Results
10.
J Clin Pathol ; 57(8): 867-71, 2004 Aug.
Article in English | MEDLINE | ID: mdl-15280410

ABSTRACT

AIMS: To compare intratumorous microvessel density (MVD) and clinicopathological features in two different groups of hepatocellular carcinoma (HCC), namely: hepatitis B virus (HBV) related HCC (B-HCC) and HCV related HCC (C-HCC). METHODS: Fifty consecutive cases each of B-HCC and of C-HCC were studied. Microvessel numbers were assessed by staining for the antigen CD34; in each case, three areas with the highest numbers of microvessels were counted in both the intratumorous and the surrounding non-tumorous tissue; the mean value represented the final MVD. RESULTS: Patients with B-HCC were significantly younger than those with C-HCC (mean age, 60.1 (SD, 4.1) v 66.4 (4.3) years); no significant differences were seen for sex or Child's class distribution. The tumour diameter was larger in B-HCCs than in C-HCCs (mean, 5.6 (SD, 1.8) v 3.8 (1.8) cm). Tumour microsatellite formation was significantly higher in C-HCCs (12 v 4 cases). No differences were found for histological subtype, degree of differentiation, tumour encapsulation, and vascular invasion. The mean MVD value was significantly higher in tumorous (mean, 54 (SD, 13.8) v 38 (8.9)) and in the surrounding non-tumorous liver tissue (mean, 15 (SD, 4.3) v 7 (3.1)) of C-HCCs. CONCLUSIONS: C-HCCs present as smaller tumours in older patients, with a higher incidence of tumour microsatellite formation and higher MVD values both in the tumorous and the non-tumorous areas, suggesting a link between HCV infection, angiogenesis, and hepatocarcinogenesis.


Subject(s)
Carcinoma, Hepatocellular/blood supply , Carcinoma, Hepatocellular/virology , Hepatitis B/pathology , Hepatitis C/pathology , Liver Neoplasms/blood supply , Neovascularization, Pathologic/pathology , Age Factors , Aged , Antigens, CD34/analysis , Carcinoma, Hepatocellular/pathology , Chi-Square Distribution , Female , Hepacivirus , Hepatitis B virus , Humans , Immunohistochemistry/methods , Liver Neoplasms/pathology , Liver Neoplasms/virology , Male , Microcirculation , Middle Aged , Statistics, Nonparametric
11.
Eur J Echocardiogr ; 5(1): 72-5, 2004 Jan.
Article in English | MEDLINE | ID: mdl-15113015

ABSTRACT

We report a patient with a mass originating from the anterior mitral valve leaflet causing severe left ventricular outflow tract obstruction. Noninvasive imaging provided the best diagnostic tools for diagnosis. Histological findings showed a very rare giant blood cyst of the mitral valve.


Subject(s)
Cysts/complications , Cysts/diagnostic imaging , Mitral Valve , Ventricular Outflow Obstruction/diagnostic imaging , Ventricular Outflow Obstruction/etiology , Adult , Biopsy, Needle , Cysts/pathology , Cysts/surgery , Echocardiography, Doppler, Color/methods , Electrocardiography/methods , Female , Follow-Up Studies , Humans , Immunohistochemistry , Magnetic Resonance Imaging/methods , Severity of Illness Index , Treatment Outcome , Vascular Surgical Procedures/methods , Ventricular Outflow Obstruction/complications , Ventricular Outflow Obstruction/surgery
13.
Ultrastruct Pathol ; 25(3): 169-81, 2001.
Article in English | MEDLINE | ID: mdl-11465473

ABSTRACT

The authors present 18 cases of various nature, representing a wide spectrum of neoplastic and nonneoplastic diseases shown at Ultrapath X in quiz format for identification or diagnosis.


Subject(s)
Disease , Microscopy, Electron , Neoplasms/ultrastructure , Pathology, Clinical , Humans
14.
Ultrastruct Pathol ; 25(3): 269-73, 2001.
Article in English | MEDLINE | ID: mdl-11465481

ABSTRACT

A case of primary pulmonary rhabdomyosarcoma occurring in a 62-year-old man is reported, and a review of the literature is presented. The tumor affected the left upper lobe and involved the mediastinal lymph nodes. Immunohistochemical and ultrastructural studies supported the myogenic phenotype of the neoplasm. A left pneumonectomy was performed with complete surgical removal of the tumor. Postoperative radiotherapy was carried out. The patient is currently alive and free of disease 9 months after operation. Despite the rarity of primary pulmonary rhabdomyosarcoma, this tumor should be differentiated from other poorly differentiated pulmonary neoplasms and from metastatic sarcomas.


Subject(s)
Lung Neoplasms/pathology , Rhabdomyosarcoma/pathology , Humans , Immunohistochemistry , Lung Neoplasms/metabolism , Lung Neoplasms/ultrastructure , Male , Microscopy, Electron , Middle Aged , Rhabdomyosarcoma/metabolism , Rhabdomyosarcoma/ultrastructure
15.
Hum Pathol ; 32(5): 529-36, 2001 May.
Article in English | MEDLINE | ID: mdl-11381372

ABSTRACT

The distinction between pleural epithelial mesothelioma and peripheral lung adenocarcinoma involving the pleura is still an important diagnostic problem for surgical pathologists. The aim of our study was to identify the most specific and sensitive markers for the positive identification of mesothelioma to select a limited, appropriate panel of antibodies to differentiate between mesothelioma and adenocarcinoma. Forty-two cases of epithelial mesotheliomas and 23 cases of pulmonary adenocarcinomas were stained with the following antibodies: anticalretinin, antithrombomodulin, anti-CD44H, and monoclonal antibody HBME-1. We also studied the value of other markers in current use: cytokeratins AE1/AE3 and CAM5.2, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), Ber-EP4, B72.3, and CD15. Of the mesotheliomas, 42 stained for calretinin, 39 (92.8%) for thrombomodulin, 42 stained for CD44H, and 41 (97.6%) stained for HBME-1. Among negative markers, 4 (9.5%) mesothelioma cases stained for CEA, 5 (11.9%) stained for Ber-EP4, 6 (14.2%) stained for B72.3, and 2 (4.7%) stained for CD15. Of the lung adenocarcinomas, 2 (8.7%) cases showed reactivity for calretinin, 5 (21.7%) for thrombomodulin, 13 (56.5%) for CD44H, all for HBME-1, 22 (95.6%) for CEA, 22 (95.6%) for Ber-EP4, 8 (34.7%) for B72.3, and all for CD15. In conclusion, calretinin and thrombomodulin were the most specific positive mesothelial markers, whereas CD44H and HBME-1 showed high sensitivity but very low specificity. Among negative markers, we advocate the use of CEA and CD15 which were the most specific in differentiating mesotheliomas from adenocarcinomas.


Subject(s)
Adenocarcinoma/diagnosis , Biomarkers, Tumor/analysis , Lung Neoplasms/diagnosis , Mesothelioma/diagnosis , Pleural Neoplasms/diagnosis , Adenocarcinoma/chemistry , Antibodies, Monoclonal , Calbindin 2 , Carcinoembryonic Antigen/analysis , Diagnosis, Differential , Humans , Hyaluronan Receptors/analysis , Immunohistochemistry , Keratins/analysis , Lewis X Antigen/analysis , Lung Neoplasms/chemistry , Mesothelioma/chemistry , Mucin-1/analysis , Pleural Neoplasms/chemistry , S100 Calcium Binding Protein G/analysis , Thrombomodulin/analysis
16.
J Eur Acad Dermatol Venereol ; 14(2): 127-30, 2000 Mar.
Article in English | MEDLINE | ID: mdl-10972099

ABSTRACT

We report on a 14-year-old boy who presented with a 4-year history of acral pains and febrile episodes. On physical examination, numerous small reddish papules were present on his abdomen, located predominantly on the periumbelical region. Renal function was within normal limits. Ophthalmological examination revealed whorled opacities of the cornea (cornea verticillata) and dilated tortuous conjunctival vessels. Histopathological examination of one of the cutaneous papules showed several dilated blood vessels in the superficial dermis surrounded by collarettes of thickened rete ridges, consistent with a diagnosis of angiokeratoma. The electron-microscopic study of a skin specimen demonstrated the presence of dilated lysosomes with deposition of electron-dense bodies, some of which with laminated structure, in endothelial cells and fibroblasts. These findings were regarded as indicative of Fabry's disease. Subsequent biochemical analysis confirmed the presence of a alpha-galactosidase A deficiency in leukocytes. In conclusion, we described the clinical, histopathological and submicroscopic findings of a case of Fabry's disease, in which the combination of electron microscopic and biochemical approaches allowed the correct diagnosis.


Subject(s)
Fabry Disease , Adolescent , Cornea/pathology , Fabry Disease/diagnosis , Fabry Disease/pathology , Humans , Male , Skin/pathology , Skin/ultrastructure
18.
Histopathology ; 36(1): 26-31, 2000 Jan.
Article in English | MEDLINE | ID: mdl-10632748

ABSTRACT

AIMS: The purpose of this study was to establish whether the cell proliferation index assessed by the monoclonal antibody MIB-1 would correlate with survival in pleural malignant mesothelioma. METHODS AND RESULTS: We studied a series of seven long-term survivors with pleural malignant mesothelioma and a group of control cases with short-term survival. All cases showed MIB-1 positive cells, and labelling indices were expressed as percentage of cells with positive nuclear immunostaining by randomly counting 1000 tumour cells. A statistically significant difference was found between MIB-1 values in the long-term survival group and the control cases with short-term survival. CONCLUSIONS: Our results indicate that the differences in biological behaviour of malignant mesothelioma in long-term and short-term survivors may be explained in part by differences in tumour growth fraction and that proliferation index could represent an important prognostic parameter for this tumour.


Subject(s)
Ki-67 Antigen/analysis , Mesothelioma/mortality , Pleural Neoplasms/mortality , Adult , Aged , Cell Count , Cell Division , Female , Humans , Immunoenzyme Techniques , Male , Mesothelioma/chemistry , Mesothelioma/pathology , Middle Aged , Mitotic Index , Pleural Neoplasms/chemistry , Pleural Neoplasms/pathology , Survival Rate
19.
Ultrastruct Pathol ; 23(4): 233-40, 1999.
Article in English | MEDLINE | ID: mdl-10503742

ABSTRACT

While the analysis of the clinical, radiologic, and histopathologic features of surface osteosarcomas has been the subject of several papers, identification of the phenotypic features of these tumors has so far received little attention. The aim of the present study was to characterize the neoplastic cells of surface osteosarcomas using an ultrastructural and immunohistochemical approach. Glutaraldehyde-fixed, epoxy resin-embedded archival pieces of tissue from 8 surface osteosarcomas (4 parosteal low-grade osteosarcomas, 3 dedifferentiated parosteal osteosarcomas, 1 periosteal osteosarcoma) were investigated using transmission electron microscopy. Sections of formalin-fixed, paraffin-embedded tumor specimens were employed for the immunohistochemical analysis of osteonectin and osteocalcin, two markers of cells of osteoblastic lineage, and sigma-smooth muscle actin and muscle specific actin. By electron microscopy, the tumors were composed of a mixture of neoplastic cells with varied differentiation, i.e., osteoblast-like, fibroblast-like, myofibroblast-like, and chondroblast-like. The latter were particularly abundant in the periosteal osteosarcoma. Osteocalcin expression was detected in the cytoplasm of neoplastic cells in 6 cases (66.6%), while osteonectin was expressed at least focally in all cases. The expression of the noncollagenous bone proteins was higher in low-grade osteosarcomas than in dedifferentiated osteosarcomas. sigma-Smooth muscle actin and muscle-specific actin expression were detected in 4 (44.4%) and 5 (55.5%) cases respectively, and the distribution was similar in both low-grade and dedifferentiated lesions. The results do not confirm previous observations regarding the prevalence of a specific cellular phenotype in surface osteosarcomas. Further, the myofibroblast-like cells that are present in variable numbers in these tumors are probably modified osteoblasts, since they co-express actin, osteonectin, and osteocalcin.


Subject(s)
Bone Neoplasms/ultrastructure , Osteosarcoma/ultrastructure , Actins/analysis , Bone Neoplasms/chemistry , Humans , Immunoenzyme Techniques , Microscopy, Electron , Organelles/chemistry , Organelles/ultrastructure , Osteocalcin/analysis , Osteonectin/analysis , Osteosarcoma/chemistry , Periosteum/ultrastructure
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