Nuclear factories for signalling and repairing DNA double strand breaks in living fission yeast

In mammalian and budding yeast cells treated with genotoxic agents, different proteins implicated in detecting, signalling or repairing DNA lesions form nuclear foci. We studied foci formed by proteins involved in these processes in living fission yeast cells, which is amenable to genetic and molecular analysis. Using fluorescent tags, we analysed subnuclear localisations of the DNA damage checkpoint protein Rad9, of the homologous recombination protein Rad22 and of PCNA, which are implicated in many aspects of DNA metabolism. After inducing double strand breaks (DSBs) with ionising radiations, Rad22, Rad9 and PCNA form a low number of nuclear foci. Rad9 recruitment to foci depends on the presence of Rad1, Hus1 and Rad17, but is independent of downstream checkpoint effectors and of homologous recombination proteins. Likewise, Rad22 and PCNA form foci despite inactive homologous recombination repair and impaired DNA damage checkpoint. Rad22 and Rad9 foci co-localise completely, whereas PCNA co-localises with Rad22 and Rad9 only partially. Foci do not disassemble in cells unable to repair DNA by homologous recombination. Thus, in fission yeast, DSBs are detected by the DNA damage checkpoint and are repaired by homologous recombination at a few spatially confined subnuclear compartments where Rad22, Rad9 and PCNA concentrate independently.

[Vasculitides: classification, clinical aspects and pathology. A review]

The Consensus Conference of Chapel Hill (1994) laid a common base for a standardized classification of vasculitides which, after a pre-existing historical diversity, enabled a comparison of different studies. The criteria for this classification are foremost anatomico-pathological and are based on the caliber of affected blood vessels. In addition the quality of the inflammatory reaction, and the entirety of clinical symptoms, as well as the results of immunological tests are included. Moreover a unified pathogenetic concept is proposed for all types of vasculitis. The diagnosis of vasculitis of large, medium or small vessels is made primarily by biopsies and examination of HE-stained sections. However, overlap of calibers of vessels affected and lack of specificity of inflammatory reaction with individual vasculitis types have to be paid attention to. Immunohistochemical methods are only rarely routinely applied. In contrast the complete clinical picture and the results of immunological laboratory tests (especially AntiNeutrophilCytoplasmicAntibodies, ANCA) play an important role in the differential diagnosis of various vasculitis types. Definitions, clinical findings and pathology of the various types of vasculitis are described. Also mentioned are secondary vasculitides, e.g concurrent to collagen diseases or infections. Not only the diagnosis of vasculitis but also the recognition of the specific type and, last but not least monitoring by histological controls, may be decisive for an optimal therapy.

Injizierbares Silikon

The injection of fluid silicone was formerly an acceptable therapy for recontouring post-traumatic or age-related changes of the face and neck. About 20 years after the use of silicone injections, the number of patients presenting with late complications is increasing. Such complications include migration of the silicone, granuloma formation, chronic cellulitis, skin ulcers and and scarring, all of which are difficult to treat medically or surgically. Recent data in the literature support the notion that fluid silicon is a potential carcinogen. These patients require a careful approach combining the limited surgical possibilities with the support needed to live with such a problem. Using a case report as an example, we discuss the diagnostic and therapeutic problems associated with this phenomenon which is relatively uncommon in Europe.

Refinement of velopharyngoplasty in patients with cleft palate by covering the pharyngeal flap with nasal mucosa from the velum

The velopharyngoplasty performed using the popular Sanvenero-Rosselli method improves the speech quality of patients with cleft palate suffering from persistent velopharyngeal insufficiency despite successful closure of the hard and soft palates. However, often a relatively narrow pharyngeal bridge results due to healing not only by granulation and scar contraction, but also due to the insertion of the inferior tip of the flap into a narrow bed. Elevation of two velar flaps with nasal mucosa to cover the exposed muscular undersurface of the pharyngeal flap produces a broader recipient bed into which the pharyngeal flap can be spread. The speech quality of 27 patients treated with this modified method (group B) was compared with that of 27 patients without this modification (group A). Eight weeks after velopharyngoplasty (followed by uneventful wound healing) the speech quality of group B was significantly better than that of group A (p<0.03 MannWhitney U-test). This difference was even more evident when comparing the preoperative with the postoperative speech quality (p<0.005). Thus, covering the exposed muscular layer of the pharyngeal flap with nasal mucosa of the velum is an important modification of velopharyngoplasty for the improvement of speech quality.

[Hyalinizing spindle cell tumor with giant rosettes. Case report with immunohistochemical characterization]

This is a case of a 46-years-old male patient with a long-standing history of lower abdominal complaints. A 6-cm measuring tumor was detected by CT and subsequently surgically removed. Classification of this tumor and prognosis was problematic in frozen section and paraffin-embedded material, including immunohistochemical studies. The immunohistochemical findings were compatible with myofibroblastic differentiation of tumor cells. The histologic pattern resembled a "hyalinizing spindle cell tumor with giant rosettes" as recently published. Even if there were certain discrepancies in the immunohistochemical findings in our case, we also recommended treating this tumor as a low-grade sarcoma. The malignancy was also supported by marked proliferative activity demonstrated by MIB 1/KI 67 expression in numerous tumor cells. Finally, it has not yet been determined whether the hyalinizing spindle cell tumor is a pattern associated with a certain cellular differentiation or a pattern common to several mesenchymal tumor types.

[Cutaneous and subcutaneous soft tissue tumors]

Superficial, especially cutaneous soft tissue tumors deserve attention because of their special biology, often with better prognosis than their deep counterparts. This fact also has been considered in the TNM Classification/UICC, as well as in the Typing of Soft Tissue Tumors/WHO.-Basically all types of soft tissue tumors can also be found in subcutaneous and cutaneous localisation. Dermatofibrosarcoma protuberans, however, is a typical superficial tumor involving cutis and frequently the superficial subcutis. Superficial leiomyosarcoma and atypical fibroxanthoma are examples of sarcomas, which in spite of histological criteria, which generally are associated with high grade malignancy, behave as low grade malignant tumors, i.e. chiefly with risk of recurrency albeit negligible risk of metastases. Angiosarcoma and epitheloid sarcoma, on the other hand, may also metastasize, even if restricted to the cutis. Here histological criteria as numerous mitoses, cellular atypia and tumor necrosis, may additionally influence the prognosis. In conclusion it is evident that exact tumor classification is the basic requirement for an optimal, prognosis-adapted therapy. Prerequisite, however, is a precise clinico-pathological correlation to understand the biology of the different tumor entities.

Psychotropic drug prescription in a psychiatric university hospital

A retrospective survey on drug prescription over a one-year period (1989) in 1083 patients (48.3% of whom were male) hospitalized in a psychiatric university hospital in Switzerland and a 35-day prospective study (1992) on the prescription of "as needed" (prn) medication in a closed and an open ward were carried out. Their aim was to establish a basis for a monitoring of prescription habits and for pharmacoeconomic considerations. In the retrospective study, 48.3% of the patients were male. The mean duration of hospitalization of the patients was 47.0 +/- 68.1 days (mean +/- s.d.). Only 11 out of the 1083 patients (1%) were without psychotropic medication. The mean (+/- SD) number of drugs/day the patients were prescribed was 4.6 +/- 2.8, including 3.2 +/- 1.7 psychotropic drugs. Patients suffering from schizophrenia (67 d) or from unipolar depression (67.4 d) were hospitalized for the longest periods. Antipsychotics (67.5% of the patients) were the most frequently prescribed psychotropic drugs, followed by anxiolytics (42.2%), antidepressants (28.3%), hypnotics (31.4%) and mood stabilizers (7.1%). Antiparkinsonian agents accounted for 4.6% of all prescriptions. Levomepromazine, haloperidol (30.9% of all patients) and clotiapine were the most often prescribed neuroleptics, and clozapine was administered to only 6.4% of all patients. Among the antidepressants, maprotiline (11.9% of all patients) was more frequently prescribed than the classical tricyclic antidepressant amitriptyline, while the only available SSRI fluvoxamine and MAO inhibitors were rarely used. The most frequently prescribed anxiolytics were clorazepate (28.2% of all patients), lorazepam, bromazepam, and prazepam. Among the hypnotic drugs, chloral hydrate (11.5%) was more frequently administered than the first-ranking benzodiazepine flunitrazepam (7.8%). In the prospective study, 97% and 77% of the patients (n = 55) of the closed (n = 29) and of the open ward, respectively, were prescribed "as needed" (prn) drugs. However, only 71 and 80%, respectively, of these patients finally received the drug. The frequency of prescription was 34.9% for neuroleptics, 15.1% for anxiolytic drugs, 8.2% for non-benzodiazepine hypnotics and only 2.1% for benzodiazepine hypnotics. The most frequently prescribed neuroleptic drug was clotiapine (18% of all patients), but finally, only 29% of the prescribed doses were administered. Studies of this type are biased by the fact that local habits of prescription do not allow generalisation of the findings. Such surveys should be carried out more frequently and simultaneously in different centers. Critical comparisons could help to optimize treatment.

[Acquired cystic kidney disease in patients on long-term dialysis: a retrospective study of 125 autopsies. Part 2: tumors]

The possible relation of acquired cystic kidney disease to renal cell carcinoma resulted in an interdisciplinary concern about this disease. Kidneys from 125 autopsies of dialysis patients were studied. Twenty-four of the patients had tumors. Beside four renal adenocarcinomas and two urothelial carcinomas, incidental small tumor nodules were described in 15.1%. Men had more nodules than women. Patients with nodules had a higher average cyst count, often with multi-layered epithelium. There was no difference in age or time of dialysis. This suggests a factor which mediates cyst and tumor proliferation, independent from the time of dialysis. With the improvement in imaging techniques, an increasing number of small renal tumors will be found. Further studies are necessary to evaluate the risk of small kidney cell tumors and their association with acquired cystic kidney disease.

[Acquired, cystic kidney disease in chronic dialysis patients: a retrospective study of 125 autopsies. 1: Cysts]

In acquired cystic kidney disease cysts develop in kidneys with impaired excretory function. Bleeding, cyst infection and a possible relation to kidney cell carcinoma resulted in an interdisciplinary concern about this disease. Kidney tissue slides from 125 autopsies of dialysis patients were studied. Of totally 967 cysts, 52% were lined by a cuboidal epithelium, with either clear or eosinophilic cytoplasm; 34% showed a flat epithelium. Multilayered epithelium was present in 8.3% and bleeding stigmata in 5.3%. Cyst counts rose with duration of dialysis, with a higher average cyst count in men. There was no correlation between cysts and (1) age, at the time of death of at the beginning of dialysis, (2) type of renal disease, (3) blood group, (4) body weight, (5) coronary heart disease, and (6) diabetes mellitus. More studies on the development of cysts, parameters of cyst formation and complications are necessary, as they are the basis for the interpretation of new imaging techniques, as well as, for a clinical risk assessment.

[Myofibroblasts. Review out outlook]

When studying inflammation and wound healing, peculiar fibroblasts with ultrastructural similarities to smooth muscle cells were described by a group of pathologists associated with Guido Majno (GM) and Giulio Gabbiani (GG), subsequently called myofibroblasts. Similar cells were also found later in human granulation tissue, palmar fibromatosis and in stromal reactions with invasive cancers. Their identification was facilitated by immunohistochemical methods. Some neoplastic cells, for instance in MFH, also revealed characteristics compatible with myofibroblasts. Myofibroblasts are conceived of as modulated fibroblasts. Cytokines may serve as mediators for activation and contractile modification of fibroblasts. In this context monitoring of a tumor-like overproduction of myofibroblasts or an underproduction with non-union of wounds might also be feasible. Moreover, better understanding of the role of myofibroblasts concerning the transition from in situ carcinomas into invasive growth may have therapeutic perspectives. Myofibroblasts apparently not only show a temporary existence in disease, but also can be found under normal conditions in several regions, such as the skin, periodontal ligaments, or pulmonary septa.

Native pulmonary muscular proliferation

Four cases with native pulmonary muscular proliferation (NPMP) are reported. The etiology of this rare condition is unknown. A hamartomatous process is discussed. In spite of its rarity the correct diagnosis of this condition is important. Both clinically and histologically in transbronchial biopsies, NPMP may be mistaken for pulmonary lymphangioleiomyomatosis (PLAM). Distinction of these 2 conditions is adamant, as PLAM has a poor prognosis, and, moreover may be associated with general disease, as with tuberous sclerosis. Whereas the typical distribution of more mature desmin positive muscle cells in a dense center core and more immature desmin negative radiating peripheral muscle cell proliferation with fascicular pattern in NPMP may be recognized in open lung biopsy, these differences may not become evident in small transbronchial biopsies. Immunohistochemical methods play an important role in the differential diagnosis--as with PLAM estrogen and progesterone receptors may be expressed and, most importantly, the reaction of the HMB45-antibody appears consistently positive in muscle cells of PLAM, while negative with NPMP. Thus, recognition of this clinically innocent disease is also possible in small tissue particles.

[Spindle cell tumors and tumor-like changes of the prostate and surrounding tissue]

Spindle cell lesions of the prostate and surrounding tissues include mesenchymal and epithelial tumors and tumorlike lesions, such as postoperative spindle cell nodules (PSN) and pseudosarcomatous fibromyxoid tumors (PFMT). PSN and PFMT are possibly related fibroblastic and myofibroblastic proliferations respectively. However, they may be misinterpreted as sarcomas. PSN typically are detected incidentally several weeks or months after urological procedures such as cystoscopy. PFMT only rarely reveals a urological history, however, reaching back for several years; here, more often there is a clinical presentation with dysuria and/or hematuria. Important for the differential diagnosis of PSN and PFMT or sarcomas is not only a histological examination, including immunohistochemistry, but also a close clinicopathological correlation. Nevertheless, in some cases it may be impossible to reach a final diagnosis.

[Fibroepithelial polyp of the kidney pelvis]

Benign fibroepithelial polyps of the renal pelvis are rare. Because of suspected malignancy in imaging procedures an ureteronephrectomy was carried out in the reported case. Histology, however, yielded no evidence of malignancy. The diagnosis of benign fibroepithelial polyp was entertained. It remains an open question whether the pathologic changes represent a hamartoma or a reactive postinflammatory process, revealing primitive myxoid stroma within the polypous portion and increasing fibrosis with diffuse submucosal involvement of the ureteral basis.

Malignant fibrous histiocytoma: histomorphological pattern or tumor type

During the past years MFH has obviously been used as a diagnostic waste basket for hard to classify tumours of all kinds. Immunohistochemistry revealed insights into cellular differentiation of neoplastic proliferations, also raising new questions because of unexpected antigen expression, as, for instance, cytokeratins in MFH. Thus, a number of tumours originally diagnosed as MFH could be reclassified, i.e., as leiomyosarcoma, melanoma or anaplastic carcinoma. Nevertheless, there remain a certain number of sarcomas which lack any evidence of special cellular differentiation. These proliferations of primitive mesenchymal or fibroblastic cells, often with a typical histological, storiform pattern, qualify as MFH. Using these strict criteria, the diagnosis of MFH will become rarer, though not obsolete (like hemaugioperizytoma years ago!).

Structural aberrations of chromosome 6 in three uterine smooth muscle tumors

Clonal karyotypic alterations of chromosome 6 in three uterine smooth muscle tumors are reported. In all cases an apparently identical breakpoint on the short arm of chromosome 6 was found. Two cases displayed the histologic features of cell-rich myomas with severe nuclear atypia but no clear evidence for malignancy. The remaining case was a primary uterine leiomyosarcoma of an 80-year-old patient showing an apparently balanced reciprocal chromosomal translocation, t(1;6)(p32-33;p21.3), as the sole karyotypic abnormality. This type of aberration has not been reported before in leiomyosarcomas. Because of the nuclear atypia in the other myomas with a breakpoint involving the short arm of chromosome 6 we feel that this cytogenetically recognizable but rare subgroup of uterine smooth muscle tumors warrants a careful clinical follow-up.

[Sclerosing adenosis of the prostate. Carcinoma simulation]

Sclerosing adenosis of the prostate is a benign lesion, which was not recognized until a few years ago. As in sclerosing adenosis of the breast, a background of various hyperplastic changes is commonly also present in the prostate. An incidence of 2.8% was reported in one series of resected hyperplastic prostatic glands. As demonstrated in this case report, the main problem lies in the differential diagnosis between sclerosing adenosis and highly differentiated adenocarcinoma of the prostate. Histological diagnosis of sclerosing adenosis based on routine HE sections is supplemented by immunohistochemical methods. Important diagnostic criteria of sclerosing adenosis are the presence of basal cell differentiation, which is demonstrated by cytokeratin 903, and signs of possible myoepithelial differentiation, with expression of S-100 and/or smooth muscle actin. These antibody expressions are lacking with in the presence of adenocarcinoma of the prostate. Nevertheless, in a small number of cases this differential diagnosis remains impossible, even after the application of immunohistochemical methods. Further studies are needed to shed some light on the relations between sclerosing adenosis, atypical adenomatous hyperplasia and adenocarcinoma of the prostate. So far, there appears to be no evidence of a direct relationship between sclerosing adenosis of the prostate and an elevated risk of carcinoma.

[Interstitial nephritis with acute renal failure in Ascaris lumbricoides infection]

A girl aged 14 years, 8 months presented with painful swelling of cervical lymph nodes. On frozen section malignancy could be ruled out. There were nonspecific inflammatory changes. In the presence of a prominent eosinophilic reaction the possibility of a drug reaction had been suggested. Because of decreasing renal function, dialysis was started 1 day after lymph node extirpation. A renal biopsy revealed acute interstitial nephritis-again with eosinophils. At this point parasitosis was discussed. There was a slightly elevated titer for filariasis. Shortly thereafter, also eggs of Ascaris lumbricoides were found in the feces. A pulmonary infiltrate made its appearance, with eosinophils in the pleural fluid. About 20 days later, after dialysis and anti-Ascaris therapy, the patient was discharged with no further complaints. Repeated controls revealed no further complaints, especially no more Ascaris lumbricoides. This case had two special aspects: (1) initial presentation with painful cervical lymph node swelling, and (2) subsequent acute renal failure. The literature revealed only four patients with Ascaris lumbricoides infection and acute interstitial nephritis, all described by one author (Zollinger). Perhaps a special hyperergic situation in this patient was responsible for the renal involvement; however, this complication should be watched for in all cases Ascaris lumbricoides infections.

Cytogenic and molecular analysis of an aggressive angiomyxoma

Aggressive angiomyxoma is a rare mesenchymal tumor occurring mainly in the vulvar region extending into the paravaginal and perirectal region. Histologically, this tumor is rich in vascular structures and in collagen fibers and is of myxoid appearance. Cytogenetic and molecular analysis was performed on a case of an aggressive angiomyxoma and revealed clonal karyotypic abnormalities. All 50 metaphases analyzed showed a translocation involving the chromosomal region 12q14-15. Chromosomal aberrations involving the breakpoint region 12q14-15 are frequently seen in a variety of other mesenchymal tumors as uterine leiomyomas, lipomas, hamartomas of the lung, liposarcomas, or hemangiopericytomas. Therefore, this breakpoint region seems to be the most frequent chromosomal abnormality associated with the initiation of human mesenchymal neoplasms. To narrow down the breakpoint region on a molecular level in the cells of the angiomyxoma we performed FISH analysis with different cosmid clones originating from a yeast artificial chromosome and cosmid contig overspanning parts of the region 12q14-15. We were able to narrow down the region to approximately 70-80 kb belonging to an area designated a multiple aberration region, because it also includes the breakpoints of leiomyomas, lipomas, and pleomorphic adenomas with 12q13-15 abnormalities. Our molecular and cytogenic data suggest that angiomyxomas or at least a subset of them molecularly belong to the benign group of mesenchymal tumors showing multiple aberration region involvement.

Adult Wilms' tumor. Report of two cases and review of the literature

BACKGROUND

Wilms' tumor is rare in adults. The recommended treatments for patients with Stage II adult Wilms' tumor with favorable histology (FH) nephroblastomas are conflicting.

METHODS

Two patients with Stage II, favorable histology, adult nephroblastomas are described. Current treatment modalities are discussed and the literature is reviewed.

RESULTS

The first patient, a 52-year-old woman, probably had a late local relapse of a Wilms' tumor 21 years after nephrectomy because of a renal tumor originally diagnosed as reticular sarcoma. In this case, a recurring or an extrarenal Wilms' tumor should have been considered. After the tumor was removed, the patient received adjuvant chemotherapy with dactinomycin and vincristine and was disease free 44 months after diagnosis. The Wilms' tumor in the second patient, a 33-year-old woman, was discovered accidentally and classified as Stage II/FH based on preoperative biopsy. She was treated with radical nephrectomy and adjuvant chemotherapy with dactinomycin and vincristine. This patient was disease free 24 months after surgery.

CONCLUSIONS

Surgery and two-drug chemotherapy with dactinomycin and vincristine is suggested for patients with Stage II adult Wilms' tumor with FH nephroblastomas.

[Explosive metastasis of a cancer of the kidney pelvis in analgesic kidney]

A 48-year-old male experienced sudden pain in the right flank and macrohematuria with subsequent repeated episodes of painless macrohematuria. In the radiological work-up, CT was interpreted as inflammatory enlargement of the right kidney and MRI diagnosed renal vein thrombosis. There was some suspicion that there might be a malignancy. Five months later the patient had to be admitted to the hospital, because of increasing flank pain, desiccation and general signs of inflammatory disease. Radiological changes compatible with pulmonary metastases were found. Biopsy of enlarged mediastinal lymph nodes revealed undifferentiated carcinoma. Because of the expression of Cytokeratin primary urothelial carcinoma was suspected. The patient then deteriorated rapidly. No further specific therapy could be carried out. Death was chiefly caused by respiratory insufficiency 5 months after the first episode of pain and 1 month after admission. Autopsy revealed a poorly differentiated urothelial carcinoma of the right renal pelvis, with extensive carcinomatous angiomatosis and metastases to the left kidney, lungs, and regional and mediastinal lymph nodes. Independently of the carcinoma, both kidneys also showed interstitial nephritis, papillary necrosis and capillarosclerosis, compatible with analgesic-user kidney ("phenacetin kidney") in the absence of a corresponding history.

Pulmonary myofibroblastic nodules with "amianthoid features"

Two consecutive publications appeared 1989 in the same number of a medical journal, which reported peculiar spindle-cell tumors with dense collagen or hyaline nodules, exclusively in inguinal lymph nodes of adults. The first series of 22 cases bore the title "Palisaded myofibroblastoma, a benign mesenchymal tumor of lymph node", the second with 6 identical cases "Intranodal hemorrhagic spindle-cell tumor with "amianthoid" fibers". The following case report deals with a similar tumorous lesion, with multiple small pulmonary nodules, without recognizable lymph node constituents.

[Fatal course of juvenile chronic arthritis]

Case report of a young man suffering from seropositive juvenile arthritis who succumbed to the consequences of cerebral vasculitis. Postmortem generalised arteritis was found affecting mainly brain and kidneys. There were no laboratory signs of an inflammatory process during the months before his death nor hypergammaglobinaemia or decrease of complement. The generalised arteritis manifested itself solely as mononeuritis multiplex with eosinophilia. Thus even with discrete signs such as these severe vasculitis ought to be considered for appropriate treatment to be instituted.

Cytoskeletal heterogeneity of an epithelioid sarcoma with expression of vimentin, cytokeratins, and neurofilaments

We studied an unusual sarcoma with morphologic features diagnostic of epithelioid sarcoma by conventional light microscopy, transmission electron microscopy, and immunohistochemistry. The primary tumor, which was located in the deep soft tissues of the buttock of a 32-year-old woman, and its metastases to lymph nodes, liver, and lung were available for investigation. The histomorphological and ultrastructural appearance of the primary tumor and its metastatic deposits were typical of epithelioid sarcoma. Immunohistochemistry revealed a strong and uniform reactivity for vimentin in both the primary tumor and its metastases. In contrast, a marked cytoskeletal heterogeneity became evident for cytokeratins and neurofilaments, which were observed exclusively in lymph node metastasis. To our knowledge, the observation of neurofilaments in epithelioid sarcoma has not previously been reported.

Malignant fibrous histiocytoma. History, histology, histogenesis

At the XVI. International Congress of the International Academy of Pathology (Vienna, 1986), a session was dedicated to the classification of soft tissue tumors. At this occasion a critical review of malignant fibrous histiocytoma (MFH) was presented. A) The history of MFH revealed that this tumor had been known for many years under a variety of names. Moreover, MFH apparently had frequently been misinterpreted as other tumor types, as for instance rhabdomyosarcoma. Today, there is a discrepancy between the high incidence of MFH among soft tissue sarcomas and its underrepresentation in some widely used tumor classifications. B) The histological appearance may be fully developed and typical for MFH. However, it also may be merely compatible with MFH in less typical tumor areas. Regional differences in morphological appearance may be pronounced. Differential diagnosis can be helped by histochemical methods. C) Histochemical methods--among others--also help to shed light on the histogenesis. More recent findings point to MFH, as a tumor of fibroblasts rather than histiocytes with similarities to loose areolar connective tissue. Although MFH-like areas may occur focally within a variety of different tumors, there remains a large group of sarcomas which do not display any signs of further differentiation even after careful work-up. In these cases the application of the term MFH, as it is understood today, appears to be justified.

[Immunohistochemical methods in the diagnosis and differential diagnosis of mesenchymal skin tumors]

TNM classification, including staging and grading, cannot replace histogenetic classification of mesenchymal skin tumors; moreover, histogenetic classification is the basis for correct interpretation of the morphological criteria of malignancy. Histogenetic tumor classification can be improved by special methods, such as immunohistochemical studies of routinely formalin-fixed, paraffin-embedded material; such studies are especially advantageous in tumor diagnosis. Immunohistochemical methods are also useful in classifying less well differentiated mesenchymal tumors, which otherwise would be descriptively designated as round-celled, spindle-celled, pleomorphic, myxoid, epitheloid or pericytomalike sarcomas. Moreover, further knowledge can also be acquired about tumors with characteristic structure, but uncertain histogenesis. A prerequisite for optimal results is careful comparison of the morphological findings with routine (H&E) strains and immunohistochemical reactions. Thus, overinterpretation and misinterpretation can also be avoided in artefacts which, if misinterpreted, could have grave consequences.

Epitheloid hemangioendothelioma of the scalp. A case report with immunohistochemical and ultrastructural study

A case of an epitheloid hemangioendothelioma of the skin and subcutaneous tissue of the scalp is described. Clinically and histologically a (metastatic) carcinoma had been considered in differential diagnosis. Of great help in recognition of the endothelial nature of this tumor was the immunohistochemical reaction with Factor-VIII associated antigen and Ulex europaeus antigen. Not only tumor cells in solid areas, but also intracytoplasmic vacuoles revealed positive staining. Thereby it could be shown, that this paranuclear vacuoles are actually compatible with developing capillary lumina. Only few tumor cells showed positive reaction with alpha-1-antichymotrypsin, pointing to a possible small histiocytic component of this tumor. Endothelial features of tumor cells and developing capillary lumina also could be demonstrated by electronmicroscopy.

N-Hydroxy-N-arylacetamides. I. Toxicity of certain polycyclic and monocyclic N-hydroxy-N-arylacetamides in rats

Of the two carcinogenic N-hydroxy-N-arylacetamides tested, N-hydroxy-4-acetylaminobiphenyl was as active as the monocyclic analogs in the oxidation of hemoglobin, whereas N-hydroxy-2-acetylaminofluorene produced less ferrihemoglobin after IP injection into female and male rats. Monocyclic N-hydroxy-N-arylacetamides, such as N-hydroxy-4-chloroacetanilide or N-hydroxyphenacetin, were more toxic than the parent N-arylacetamides, LD50 in mice being 190 mg/kg for N-hydroxy-4-chloroacetanilide vs 755 mg/kg for 4-chloroacetanilide, and 702 mg/kg for N-hydroxyphenacetin versus 1,220 mg/kg for phenacetin. The higher acute toxicities are probably due, at least in part, to the production of more ferrihemoglobin by the N-hydroxy-N-arylacetamides. Chronic toxicity of N-hydroxy-4-chloroacetanilide was tested on 10 male and 10 female Sprague Dawley rats after IP or SC injection of 20 mg (0.11 mmol)/kg twice weekly for 16 weeks into two groups of 10 animals each (five males, five females, total dose: 3.5 mmol/kg). The experiment, which was terminated after 2 years, did not yield any hint that N-hydroxy-4-chloroacetanilide was carcinogenic in the rat. Subchronic toxicity of N-hydroxyphenacetin was tested in two experiments on male and female Sprague Dawley rats after IP or SC injection of 50 or 100 mg (0.26 or 0.51 mmol)/kg. In the first experiment, two groups of 15 rats each (seven males, eight females) were injected either IP or SC with 50 and 100 mg/kg twice weekly for 29 weeks, and in the second experiment groups of 10 males and 10 females were injected SC with 100 mg/kg twice daily on 5 days a week for 12 weeks. The experiments, which were terminated after 29 weeks and 12 weeks treatment, respectively, did not provide evidence for chronic interstitial nephritis or tumor growth in the kidney. N-Hydroxy-N-arylacetamides were found to be inferior to the corresponding arylhydroxylamines in their ferrihemoglobin-forming capabilities in female rats. Large differences in activity of the arylhydroxylamines and no close relation to the number of rings was observed, N-hydroxy-2-acetylaminofluorene being the least active and N-hydroxy-4-acetylaminobiphenyl being as active as the monocyclic compounds, and exceeding all in the duration of its activity.(ABSTRACT TRUNCATED AT 400 WORDS)