Detection of elevated caspase activation and early apoptosis in liver diseases.

Apoptosis has been implicated in the pathogenesis of many diseases including various forms of liver failure. The apoptotic process is essentially regulated by intracellular proteases, called caspases, which cleave several vital proteins. Despite the rapid elucidation of apoptotic signaling cascades, however, almost no information exists about the activation of caspases in situ. In the present study, a monoclonal antibody was employed which selectively recognized cleavage site-specific fragments of the caspase substrate cytokeratin-18. We demonstrate that this antibody labeled apoptotic hepatocytes in culture and, in addition, could be used to monitor caspase activation in formalin-fixed tissue biopsies. In liver sections of different liver diseases an increased number of early apoptotic cells was detected which were not found in normal tissue. Our data reveal that hepatobiliary diseases are characterized by elevated caspase activation and apoptosis, which can be specifically detected in situ by a cleavage site-specific antibody against cytokeratin-18.

Neuroendocrine differentiation in hepatoblastoma. An immunohistochemical investigation.

Hepatoblastoma exhibits a wide range of epithelial and mesenchymal lines of differentiation. Neuroendocrine differentiation in this tumor has not previously been reported. We investigated seven hepatoblastomas of different subtypes (five pure epithelial hepatoblastomas, including one small-cell hepatoblastoma, and two mixed hepatoblastomas) using a broad panel of antibodies against epithelial, mesenchymal, neural, and neuroendocrine markers, alpha-1-antitrypsin (alpha 1-AT), alpha-1-antichymotrypsin (alpha 1-ACT), alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), serotonin, and 14 regulatory peptides. Chromogranin A-immunoreactive neuroendocrine tumor cells, some of which also exhibited immunoreactivity for serotonin and somatostatin, were found in the fetal and embryonal parts of the mixed hepatoblastomas. The osteoid-like material in the mixed hepatoblastomas contained cells with immunoreactivity for chromogranin A, neuron-specific enolase, keratin, and alpha 1-AT, alpha 1-ACT, AFP, and CEA, in addition to S-100 protein and vimentin. Parallels to the neuroendocrine differentiation in hepatoblastomas are found in tumors of the gastrointestinal tract and bronchopulmonary tree. These tumors may also exhibit a neuroendocrine component; that is, multidirectional differentiation may occur, as in hepatoblastoma. The immunoreactivity of some of the cells of the osteoid-like material for keratin, alpha 1-AT, alpha 1-ACT, AFP, CEA, and chromogranin A suggests that these cells--and probably the surrounding material--are of epithelial origin.

Squamous cell carcinoma of the gastric stump. A case report and review of the literature.

Adenosquamous and pure squamous cell carcinomas of the stomach are very rare. This report is apparently the first published case of pure squamous cell carcinoma of the gastric stump. It occurred in a 67-year-old patient 37 years after Billroth II resection. This case satisfied the criteria established in the literature for the diagnosis of gastric squamous cell carcinoma. A diagnosis of adenosquamous carcinoma was excluded by extensive histologic investigation of a large number of tissue samples--a total 122 sections from 25 blocks--that revealed neither glandular structures nor mucin. The tumor stroma contained an unusually large number of eosinophils. Immunohistochemically, the tumor cells reacted with a monoclonal antibody against keratin (KL1), but not with antibodies against neuroendocrine or endothelial markers, or alpha 1-antichymotrypsin. The tumor may possibly originate from ectopic squamous epithelium, squamous metaplasia of the gastric mucosa, or an undifferentiated mucosal stem cell. However, we excluded an endothelial origin (which has been proposed by other authors) on the basis of immunohistochemical findings.

Immunoreactivity of human tissue mast cells: nonspecific binding of primary antibodies against regulatory peptides by ionic linkage.

Tissue mast cells (TMC) are known to react with antibodies against various regulatory peptides (RP). The specificity of such reactions was investigated by various methods in this study. When normal immunohistochemical staining procedures were employed. TMC in the vermiform appendix and in a cutaneous mastocytoma reacted with antibodies against ACTH, Leu-enkephalin, Met-enkephalin, and peptide histidine isoleucine (PHI). Antibody specificity was tested by absorption controls, and staining specificity by varying the concentration of the primary antibodies and the pH and sodium chloride concentration of the buffer used for rinsing and diluting. In absorption controls, staining of the TMC by anti-PHI was diminished but staining by anti-ACTH, anti-Leu-enkephalin, and anti-Met-enkephalin remained unchanged. Unlike control reactions, immunostaining of TMC with antibodies against RP exhibited marked dependence on antibody concentration and the pH and sodium chloride concentration of the buffer. Alkalization of the buffer led to an obvious increase in the reaction with antibodies against RP, and lowering the pH to 6.0 usually resulted in abolition of the reaction. These results indicate that the immunostaining of TMC with antibodies against RP, including PHI, was nonspecific. It is postulated that the granules of TMC bind certain antibodies by a cation-exchange mechanism involving ionic interactions with positively charged groups in the F(ab')2 and/or Fc segments.

A new rapid immunohistochemical staining technique using the EnVision antibody complex.

Rapid immunohistochemical investigation, in addition to staining with hematoxylin and eosin, would be useful during intraoperative frozen section diagnosis in some cases. This study was undertaken to investigate whether the recently described EnVision system, a highly sensitive two-step immunohistochemical technique, could be modified for rapid immunostaining of frozen sections. Forty-five primary antibodies were tested on frozen sections from various different tissues. After fixation in acetone for 1 min and air-drying, the sections were incubated for 3 min each with the primary antibody, the EnVision complex (a large number of secondary antibodies and horseradish peroxidase coupled to a dextran backbone), and the chromogen (3,3'diaminobenzidine or 3-amino-9-ethylcarbazole). All reactions were carried out at 37C. Specific staining was seen with 38 antibodies (including HMB-45 and antibodies against keratin, vimentin, leukocyte common antigen, smooth muscle actin, synaptophysin, CD34, CD3, CD20, and prostate-specific antigen). A modification of the EnVision method allows the detection of a broad spectrum of antigens in frozen sections in less than 13 min. This method could be a useful new tool in frozen section diagnosis and research. (J Histochem Cytochem 49:623-630, 2001)

Detection of infection in postoperative orthopedic patients with technetium-99m-labeled monoclonal antibodies against granulocytes.

A prospective study of 106 orthopedic patients was performed for the detection of infection in the early postoperative stage using 99mTc-labeled murine Mabs directed against epitopes on granulocytes. Accuracy was 81% in the hips (n = 26), 81% in the thigh (n = 21), 84% in the knee (n = 19), and 100% in the tibia (n = 27). The technique did not work well in the spine where false-negative results were observed in the three patients studied. One patient suffered transient swelling of the eyelids following injection. Optimal imaging results were obtained 2-6 hr postinjection.

Expression of the p53 tumour suppressor gene in human placenta: an immunohistochemical study.

Since human trophoblast undergoes extensive proliferation and exhibits invasive growth comparable to that of a malignant tumour, human placenta at various different stages of gestation was investigated immunohistochemically with the monoclonal antibody Ab-6 for expression of the p53 tumour suppressor gene. p53 protein was detected in the nuclei of a few trophoblastic cells, almost all belonging to the cytotrophoblast and only very few to the syncytiotrophoblast, in nearly all specimens investigated (first trimester 10/10, second trimester 5/5, third trimester 4/5). First trimester trophoblast exhibited increased expression of p53 protein in the juxtastromal areas of cytotrophoblast cell islands and columns, that is, in areas where high proliferative activity and increased expression of the epidermal growth factor receptor have been described in the literature. Staining was also occasionally seen in trophoblast invading the myometrium. It is most likely that immunohistochemically detectable expression of p53 protein in the trophoblast is due not to mutation of the gene, as in malignant tumours, but rather to up-regulation of the p53 tumour suppressor gene, which could be a mechanism for controlling trophoblast proliferation.

The distribution of tissue inhibitor of metalloproteinases-2 (TIMP-2) in the human placenta.

Matrix metalloproteinases (MMPs) secreted by human cytotrophoblasts are crucial for the invasion of the placental bed by these cells. The invasive growth of the trophoblast is similar to that of malignant tumours in many respects, but, unlike the latter, it is strictly controlled. Tissue inhibitors of metalloproteinases (TIMPs) have been postulated to play a role in the control of trophoblast invasion. In this immunohistochemical study, the distribution of TIMP-2 in the human placenta was investigated. In first trimester placenta, the cytotrophoblasts in columns exhibited strong cytoplasmic staining for TIMP-2. Villous cytotrophoblasts exhibited staining of moderate intensity with accentuation at the cell membrane, especially at the interfaces with the syncytiotrophoblast and the villous stroma. Staining of the cytoplasm and apical border of the syncytiotrophoblast was weak and focal. In term placenta, the few cytotrophoblasts present exhibited a staining pattern similar to that of the cytotrophoblasts in first trimester placenta, and there was marked linear staining of the syncytiotrophoblast at the interface with the stroma. Because it is the first trimester cytotrophoblast columns that invade the placental bed, the results demonstrate that the strongest immunoreactivity for TIMP-2 in the trophoblast is found in cells that are known to produce MMPs and exhibit an invasive growth pattern. These findings indicate that TIMP-2 may be involved in autoregulation of the invasive growth of the trophoblast.

Immunoreactivity of normal and neoplastic human tissue mast cells with macrophage-associated antibodies, with special reference to the recently developed monoclonal antibody PG-M1.

There is increasing evidence in favor of the hypothesis that human tissue mast cells (MCs) are progeny of hemopoietic stem cells and are closely related to cells of the mononuclear phagocyte system. To test this hypothesis we investigated the immunoreactivity of normal/reactive MCs in 12 lymph node and tumor specimens and neoplastic MCs in 27 tissue samples from patients with various types of mastocytosis (urticaria pigmentosa, n = 13; cutaneous mastocytoma, n = 4; systemic mastocytosis, n = 6; and malignant mastocytosis, n = 4) with a panel of eight antibodies that stain macrophages or immune accessory cells and are reactive on routinely processed (paraffin-embedded, formalin-fixed) tissue. The MCs were stained by three of the macrophage-associated antibodies (namely, KP1 [CD68], Ki-M1P, and PG-M1 [CD68]), but were not stained by three other antibodies (namely, HAM56, MAC387, and LN5) or antibodies detecting immune accessory cells (DAKO-CD35 and anti-S-100 protein). While KP1 stained normal/reactive and neoplastic MCs in all the specimens investigated, Ki-M1P stained neoplastic MCs in nearly all the cases of mastocytosis but did not stain normal/reactive MCs. PG-M1 also failed to stain normal/reactive MCs and stained MCs in only approximately half of the specimens from cases of mastocytosis. Among these were most of the cases of systemic and malignant mastocytosis, but only a minority of the cases of cutaneous mastocytosis and a very few cases of urticaria pigmentosa. To summarize, (1) MCs display immunohistochemical staining properties resembling those of cells of the mononuclear phagocyte system but not those of macrophage derivatives belonging to the immune accessory cell compartment, and (2) PG-M1 and Ki-M1P are unique among the macrophage-associated antibodies investigated in that they do not stain normal/reactive MCs but exhibit preferential reactivity with the more atypical MCs in cases of systemic and malignant mastocytosis.

Systemic mast cell disease (mastocytosis). General aspects and histopathological diagnosis.

Systemic mast cell disease/mastocytosis (SMCD) is best defined as a multitopic proliferation of cytologically and/or functionally abnormal tissue mast cells (TMC). SMCD preferentially involves the bone marrow, skin, spleen, liver, and lymph nodes. The histopathological diagnosis of SMCD may be very difficult to make, and the disease is often not considered in the differential diagnosis of lymphoreticular neoplasia. In suspected cases of SMCD, basic dyes such as Giemsa and toluidine blue are useful to demonstrate the specific metachromatic granules of TMC. The naphthol AS-D chloroacetate esterase reaction has also proved to be very reliable for enzyme-histochemical identification of TMC. Major diagnostic problems may arise in cases of malignant or "aggressive" SMCD exhibiting tissue infiltrates consisting predominantly of highly atypical, non-metachromatic TMC, which are usually also only weakly reactive for chloroacetate esterase. Immunostaining with antibodies against the mast cell-specific proteases tryptase and chymase has proved to be of great value of establishing the correct diagnosis in such cases. Anti-tryptase antibodies have major diagnostic significance due to their extremely high sensitivity and specificity. The classification of SMCD is controversial, but there is increasing support for the differentiation of at least two major subtypes that differ in prognosis: (i) a benign or "indolent" variant in which skin involvement (urticaria pigmentosa-like skin lesions) is usual, but associated malignant hematological disorders are rare; and (ii) a malignant or "aggressive" variant where skin involvement is usually absent but concomitant malignant hematological disorders (myelodysplastic and myeloproliferative syndromes and acute non-lymphocytic leukemias) are very common. Preliminary molecular biological studies of a few cases of malignant SMCD using the recently developed HUMARA assay have yielded evidence that the disease is monoclonal.

Extranodal marginal zone B cell lymphoma of MALT type involving the mucosa of both the urinary bladder and stomach.

Primary lymphoma of the urinary bladder is a very rare tumour. A bladder tumour was found in a 57 year old man with obstructive dysuria. It was found by histological and immunohistohistochemical investigation to be an extranodal marginal zone B cell lymphoma. Lymphoepithelial lesions were absent, but were found in a clinically silent gastric lymphoma discovered four weeks later during staging investigations; this gastric lymphoma was negative for Helicobacter pylori by breath test and molecular biological analysis. Sequencing of the clonal immunoglobulin heavy chain gene in both tumours indicated the same precursor cell, of follicular or post follicular origin. In synopsis, the data suggested that this was a case of primary lymphoma of the bladder with involvement of the stomach. The application of a chromosome 3 specific alpha satellite probe revealed trisomy 3. A tumour with these characteristics arising as a lymphoma of the bladder with a metachronous involvement of the gastric mucosa has not been described previously.

Mastocytosis: reactive or neoplastic?

Mast cells are now known to derive from CD34+ haemopoietic stem cells in the bone marrow. However, it has not yet been established whether the various types of mastocytosis, which involve tumour-like proliferation of mast cells, are true neoplastic disorders or reactive/hyperplastic conditions. In this study, tissue specimens (five bone marrow, two spleen, one skin) from female patients with histologically confirmed mastocytosis were investigated with a recently developed polymerase chain reaction assay for the determination of clonality of female cells using the human androgen receptor gene (HU-MARA). Mast cells purified to near homogeneity from hysterectomy specimens served as a control. The findings in bone marrow and skin either were not reproducible, or indicated polyclonality. However, both spleen specimens exhibited monoclonality. In addition, DNA analysis by flow cytometry was performed and revealed a diploid chromosome content with proliferation indices of under 8% in all the specimens. This is the first molecular biological study to indicate that mastocytosis is indeed neoplastic in nature.

Expression of adhesion molecules in the lower uterine segment during term and preterm parturition.

Term and preterm cervical ripening and dilatation have similarities with an inflammatory reaction. Since cell adhesion molecules are involved in this process, investigations on the expression of intercellular adhesion molecule-1, endothelial leukocyte adhesion molecule-1, vascular cell adhesion molecule-1, and platelet endothelial cell adhesion molecule in the lower uterine segment and in vitro experiments on human umbilical vein endothelial cells were performed. In addition, current reports on expression of endothelial adhesion molecules by the uterine cervix were summarized. Cell adhesion molecule expression by lower uterine segment and uterine cervix in term and preterm parturition was measured using immunohistochemistry, enzyme immunoassay, and Northern blot analysis. Regulation of adhesion molecule expression was evaluated in vitro by indirect immunofluorescence and flow cytometry using human umbilical vein endothelial cells. Investigations in term parturition revealed that intercellular adhesion molecule-1, endothelial leukocyte adhesion molecule-1, and vascular cell adhesion molecule-1 expression increases during parturition. In preterm labor, the expression of endothelial leukocyte adhesion molecule-1 and intercellular adhesion molecule-1 in the lower uterine segment increased. Expression of platelet endothelial cell adhesion molecule did not change in term and preterm parturition. Expression of adhesion molecules was localized mainly on lower uterine segment vascular endothelial cells and to a smaller extent on leukocytes. In vitro experiments showed that expression of adhesion molecules by human umbilical vein endothelial cells can be stimulated by tumor necrosis factor-alpha, 17beta-estradiol, prostaglandin E(2), and the antigestagen onapristone. Progesterone exerted no stimulatory effect. Cervical ripening and dilatation during term and preterm parturition are associated with an increased expression of endothelial cell adhesion molecules by lower uterine segment and uterine cervix. The expression can be modulated by pro-inflammatory cytokines, sex hormones, and prostaglandin E(2). Mechanisms controlling the extravasation of leukocytes may play a fundamental role in term and preterm parturition.

Tissue concentrations of endothelial cell adhesion molecules in the lower uterine segment during term parturition.

OBJECTIVE: To determine the concentration of endothelial cell adhesion molecules in the lower uterine segment during parturition at term. METHODS: We analyzed protein extracts from the lower uterine segments of 38 women who had nonelective cesareans at term. We measured concentrations of intercellular adhesion molecule-1, endothelial leukocyte adhesion molecule-1, vascular cell adhesion molecule-1, and platelet endothelial cell adhesion molecule-1 by enzyme-linked immunosorbent assay. Subjects were grouped according to cervical dilatation (less than 2 cm, n = 10; 2 to less than 4 cm, n = 9; 4-6 cm, n = 9; more than 6 cm, n = 10) and duration of labor (up to 6 hours, n = 14; 6-12 hours, n = 10; 12-24 hours, n = 9; longer than 24 hours, n = 5) at the time of cesarean. RESULTS: The median concentration of intercellular adhesion molecule-1 increased significantly with increasing dilatation (from 2.24 ng/mg total protein at less than 2 cm to 6.73 ng/mg at 4-6 cm) and increasing duration of labor (from 2.53 ng/mg up to 6 hours to 5.90 ng/mg at 12-24 hours). However, this study did not have adequate statistical power to identify differences in concentrations of the other endothelial adhesion molecules. CONCLUSION: The results indicate that parturition at term is associated with expression of intercellular adhesion molecule-1.

A subset of CD56+ large granular lymphocytes in first-trimester human decidua are proliferating cells.

OBJECTIVE: To determine whether the unusually high number of CD56+ large granular lymphocytes (LGL) in the decidua of early human pregnancy arises from selective migration or in situ proliferation. DESIGN: Controlled clinical study. SETTING: Academic research environment. PATIENT(S): Thirty healthy women undergoing therapeutic abortion of an intact pregnancy at 5-11 weeks' gestation. INTERVENTION(S): Decidua was obtained by suction curettage; tissue and isolated cells were subjected to immunohistochemical and flow cytometric investigation. MAIN OUTCOME MEASURE(S): Proliferation rate of LGL. RESULT(S): The proportion of CD56+ cells positive for the proliferation-associated Ki-67 antigen was found to be 7%-23.5% by three different methods of investigation. These findings are consistent with those of flow cytometric analysis of the nuclear phase, which revealed 6%-22% of the LGL nuclei to be in the phases S+G2+M. CONCLUSION(S): The various methods of investigation revealed marked proliferative activity in the LGL of early pregnancy decidua. This finding suggests that in situ proliferation may be responsible for the high density of these cells in the decidua.

Antigen-presenting cells in human endometrium during the menstrual cycle compared to early pregnancy.

OBJECTIVE: Human endometrium and early pregnancy decidua harbor a considerable and diverse population of antigen-presenting cells (APC). Changes in the number and distribution of macrophages and dendritic cells (DC) could point to a possible role of these immunocompetent cells in implantation and success of early pregnancy. METHODS: Uterine tissue was obtained from 22 women undergoing hysterectomy for bleeding disorders or dysmenorrhea and from 11 women undergoing legal abortion. Tissue was investigated with antibodies against CD14, CD68, CD83, DC-SIGN, Ki-67, and human leukocyte antigen (HLA)-DR using single and double immunohistochemical staining techniques. RESULTS: The number of CD14(+) cells was stable during all phases of the menstrual cycle and early pregnancy. In comparison to nonpregnant endometrium, DC-SIGN(+) cells showed a higher proliferation rate and were found associated in clusters with CD56(+) natural killer (NK) cells in early pregnancy. In the late secretory phase of the menstrual cycle, numbers of CD83(+) (P <.01) cells were significantly higher than in other endometrial phases and early pregnancy. HLA-DR(+) expression was significantly increased in early pregnancy but remained unchanged throughout the menstrual cycle. CONCLUSION: The presence of DC-SIGN(+) cells during the menstrual cycle and their proliferation in early pregnancy suggests an important role of these cells with regard to the balance between defense against pathogens and tolerance of the fetal allograft. Whether the increase of CD83(+) mature DC and CD68(+) macrophages in the late secretory phase is caused by hormonal stimuli and/or is due to changes of the cytokine/chemokine micromilieu remains to be investigated.

Carcinoid tumour of the middle ear. A morphological and immunohistochemical study with comments on histogenesis and differential diagnosis.

Primary carcinoid tumours of the middle ear are extremely rare, only nine cases having been reported. However, their true incidence is probably greater, since they are very difficult or impossible to distinguish from adenomas and adenocarcinomas with conventional histological stains. We describe the clinical, histological, immunohistochemical and ultrastructural findings in a carcinoid tumour of the middle ear in a 50-year-old woman. Immunohistochemical studies on non-neoplastic middle ear mucosa undertaken to investigate the histogenesis of such tumours are also reported. Histologically, the tumour consisted of both solid areas and areas of tubular structures containing intraluminal mucus. All the tumour cells reacted with the anti-keratin antibody KL 1; some were argyrophil and reacted with antibodies against neuron-specific enolase, chromogranin A, Leu-7, serotonin, pancreatic polypeptide, glucagon and lysozyme. Electron microscopy revealed dense core granules in the tumour cells. Endocrine cells could not be detected in non-neoplastic middle ear mucosa. Pancreatic-polypeptide-like immunoreactivity was demonstrated immunohistochemically in all three other published cases of carcinoid tumour of the middle ear investigated for this peptide, and glucagon-like immunoreactivity was also exhibited by one of these. Since carcinoid tumours of the middle ear often, as in this case, exhibit some degree of glandular differentiation, immunohistochemical or electron-microscopic investigation to detect neuroendocrine differentiation is of particular importance in adenomatous middle ear neoplasms.

Incidence and pattern of liver involvement in haematological malignancies.

The incidence and pattern of liver involvement in 127 liver specimens (2 biopsy and 125 autopsy specimens) from cases of acute myelogenous leukaemia (25), chronic myelogenous leukaemia (7), acute lymphatic leukaemia (5), chronic lymphatic leukaemia (9), multiple myeloma (25), low-grade non-Hodgkin's lymphoma (25), high-grade non-Hodgkin's lymphoma (24) and myeloproliferative diseases (7) were investigated histologically and immunohistochemically. Liver infiltration was found frequently in chronic leukaemia and myeloproliferative diseases (80-100%), acute leukaemia (60-70%) and non-Hodgkin's lymphoma (50-60%), but was significantly less common in multiple myeloma (32%) than in any of the other diagnostic groups. Hepatomegaly was found in over 50% of cases in all the diagnostic groups, but was not always associated with infiltration. Diffuse, non-destructive infiltration was most common: in acute myelogenous leukaemia, both the portal triads and sinusoids were usually involved; in chronic myelogenous leukaemia, multiple myeloma and myeloproliferative diseases, infiltration was mainly sinusoidal; and in lymphatic leukaemia and non-Hodgkin's lymphoma the portal triads were mainly involved. Nodular infiltration was seen in multiple myeloma and non-Hodgkin's lymphoma. The primary tumours and liver infiltrates generally exhibited the same immunophenotype, although reactivity with the antibody L26 (CD20) was only found in the primary lesion in many high-grade B-cell lymphomas. Thus, liver involvement is common in haematological malignancies, but the incidence and pattern of infiltration vary amongst the different types.

Diffuse sinusoidal hemangiomatosis of the spleen. A case report with enzyme-histochemical, immunohistochemical, and electron-microscopic findings.

Diffuse hemangiomatosis of the spleen is a very rare benign tumor in which the whole spleen is permeated by neoplastic blood vessels. It is occasionally accompanied by severe disturbances of blood coagulation. The histogenesis of this tumor remains obscure. No systematic investigations of the immunophenotype of the neoplastic endothelium have been published. We describe a case of isolated benign diffuse hemangiomatosis of the spleen in which the enzyme-histochemical and immunohistochemical findings suggested an origin in the splenic sinus endothelial cells. Some of the tumor endothelial cells reacted with UEA-1, BMA 120, antibodies against the von Willebrand factor, CD34, and CD8, an antigen which, in man, is expressed only by suppressor/cytotoxic T cells and the endothelial cells of the splenic sinuses. Enzyme-histochemical investigations revealed reactivity for nonspecific esterase and lack of reactivity for alkaline phosphatase--a pattern typical of the sinus endothelial cells. The tumor could be distinguished from other tumors/tumor-like lesions of the spleen that exhibit endothelium with characteristics typical of the splenic sinuses (peliosis, splenoma, littoral cell angioma) on the basis of its histological features. The lack of expression of histiocytic antigens by the tumor endothelium is also evidence against a diagnosis of littoral cell angioma, which also derives from the sinus endothelium. Thus, this tumor could not be identified as any of the recognized tumors/tumor-like lesions of the spleen and it is therefore proposed that it should be designated diffuse sinusoidal hemangiomatosis.

[Radiofrequency ablation of the liver in vitro: increasing the efficacy by perfusion probes]. / Radiofrequenzablation der Leber in vitro: Effektivitätserhöhung mittels perfundierter Sonden.

PURPOSE: Percutaneous radiofrequency interstitial thermal ablation is a new method in local tumour therapy. The aim of this study was to define the relations between the variable parameters and local efficacy in vitro and to evaluate optimal parameter combinations for this system. Furthermore, we studied the feasibility of increasing the volume of destroyed tissue using perfusion electrodes. MATERIAL AND METHODS: Thermal lesions were produced with radiofrequency in ex vivo pig livers. In separate experiments the parameters wattage (5-30 watts), exposure time (1-15 minutes) and tip exposure were varied. The resulting areas of tissue necrosis coagulation were measured; in 30 of 90 cases the macroscopic findings were compared to the histological findings. RESULTS: Lesion size correlated with tip exposure, wattage and procedure duration up to 10 minutes. For a tip exposure of 2 cm (3 cm) the maximal lesion volume was 18.8 cm3 (33.2 cm3) at a wattage of 20 watts (30 watts) and a procedure duration of 10 minutes. The maximal cross- (length-) diameter of these lesions was 3 cm (4 cm) for 2 cm tip exposure and 3.6 cm (4.9 cm) for 3 cm tip exposure. CONCLUSION: The parameters wattage, procedure duration and tip exposure affect the size of lesions created with radiofrequency under ex vivo conditions. Perfusion electrodes make it possible to produce larger lesions than described for non-perfused electrodes. The ablation of hepatic neoplasms up to a size of 3 cm seems to be possible with a single electrode.