C16orf72/HAPSTR1 is a molecular rheostat in an integrated network of stress response pathways

All cells contain specialized signaling pathways that enable adaptation to specific molecular stressors. Yet, whether these pathways are centrally regulated in complex physiological stress states remains unclear. Using genome-scale fitness screening data, we quantified the stress phenotype of 739 cancer cell lines, each representing a unique combination of intrinsic tumor stresses. Integrating dependency and stress perturbation transcriptomic data, we illuminated a network of genes with vital functions spanning diverse stress contexts. Analyses for central regulators of this network nominated C16orf72/HAPSTR1, an evolutionarily ancient gene critical for the fitness of cells reliant on multiple stress response pathways. We found that HAPSTR1 plays a pleiotropic role in cellular stress signaling, functioning to titrate various specialized cell-autonomous and paracrine stress response programs. This function, while dispensable to unstressed cells and nematodes, is essential for resilience in the presence of stressors ranging from DNA damage to starvation and proteotoxicity. Mechanistically, diverse stresses induce HAPSTR1, which encodes a protein expressed as two equally abundant isoforms. Perfectly conserved residues in a domain shared between HAPSTR1 isoforms mediate oligomerization and binding to the ubiquitin ligase HUWE1. We show that HUWE1 is a required cofactor for HAPSTR1 to control stress signaling and that, in turn, HUWE1 feeds back to ubiquitinate and destabilize HAPSTR1. Altogether, we propose that HAPSTR1 is a central rheostat in a network of pathways responsible for cellular adaptability, the modulation of which may have broad utility in human disease.

KCTD: A new gene family involved in neurodevelopmental and neuropsychiatric disorders

The underlying molecular basis for neurodevelopmental or neuropsychiatric disorders is not known. In contrast, mechanistic understanding of other brain disorders including neurodegeneration has advanced considerably. Yet, these do not approach the knowledge accrued for many cancers with precision therapeutics acting on well-characterized targets. Although the identification of genes responsible for neurodevelopmental and neuropsychiatric disorders remains a major obstacle, the few causally associated genes are ripe for discovery by focusing efforts to dissect their mechanisms. Here, we make a case for delving into mechanisms of the poorly characterized human KCTD gene family. Varying levels of evidence support their roles in neurocognitive disorders (KCTD3), neurodevelopmental disease (KCTD7), bipolar disorder (KCTD12), autism and schizophrenia (KCTD13), movement disorders (KCTD17), cancer (KCTD11), and obesity (KCTD15). Collective knowledge about these genes adds enhanced value, and critical insights into potential disease mechanisms have come from unexpected sources. Translation of basic research on the KCTD-related yeast protein Whi2 has revealed roles in nutrient signaling to mTORC1 (KCTD11) and an autophagy-lysosome pathway affecting mitochondria (KCTD7). Recent biochemical and structure-based studies (KCTD12, KCTD13, KCTD16) reveal mechanisms of regulating membrane channel activities through modulation of distinct GTPases. We explore how these seemingly varied functions may be disease related.

KCTD7 deficiency defines a distinct neurodegenerative disorder with a conserved autophagy-lysosome defect

OBJECTIVE

Several small case series identified KCTD7 mutations in patients with a rare autosomal recessive disorder designated progressive myoclonic epilepsy (EPM3) and neuronal ceroid lipofuscinosis (CLN14). Despite the name KCTD (potassium channel tetramerization domain), KCTD protein family members lack predicted channel domains. We sought to translate insight gained from yeast studies to uncover disease mechanisms associated with deficiencies in KCTD7 of unknown function.

METHODS

Novel KCTD7 variants in new and published patients were assessed for disease causality using genetic analyses, cell-based functional assays of patient fibroblasts and knockout yeast, and electron microscopy of patient samples.

RESULTS

Patients with KCTD7 mutations can exhibit movement disorders or developmental regression before seizure onset, and are distinguished from similar disorders by an earlier age of onset. Although most published KCTD7 patient variants were excluded from a genome sequence database of normal human variations, most newly identified patient variants are present in this database, potentially challenging disease causality. However, genetic analysis and impaired biochemical interactions with cullin 3 support a causal role for patient KCTD7 variants, suggesting deleterious alleles of KCTD7 and other rare disease variants may be underestimated. Both patient-derived fibroblasts and yeast lacking Whi2 with sequence similarity to KCTD7 have impaired autophagy consistent with brain pathology.

INTERPRETATION

Biallelic KCTD7 mutations define a neurodegenerative disorder with lipofuscin and lipid droplet accumulation but without defining features of neuronal ceroid lipofuscinosis or lysosomal storage disorders. KCTD7 deficiency appears to cause an underlying autophagy-lysosome defect conserved in yeast, thereby assigning a biological role for KCTD7. Ann Neurol 2018;84:774-788.

Whi2 is a conserved negative regulator of TORC1 in response to low amino acids

Yeast WHI2 was originally identified in a genetic screen for regulators of cell cycle arrest and later suggested to function in general stress responses. However, the function of Whi2 is unknown. Whi2 has predicted structure and sequence similarity to human KCTD family proteins, which have been implicated in several cancers and are causally associated with neurological disorders but are largely uncharacterized. The identification of conserved functions between these yeast and human proteins may provide insight into disease mechanisms. We report that yeast WHI2 is a new negative regulator of TORC1 required to suppress TORC1 activity and cell growth specifically in response to low amino acids. In contrast to current opinion, WHI2 is dispensable for TORC1 inhibition in low glucose. The only widely conserved mechanism that actively suppresses both yeast and mammalian TORC1 specifically in response to low amino acids is the conserved SEACIT/GATOR1 complex that inactivates the TORC1-activating RAG-like GTPases. Unexpectedly, Whi2 acts independently and simultaneously with these established GATOR1-like Npr2-Npr3-Iml1 and RAG-like Gtr1-Gtr2 complexes, and also acts independently of the PKA pathway. Instead, Whi2 inhibits TORC1 activity through its binding partners, protein phosphatases Psr1 and Psr2, which were previously thought to only regulate amino acid levels downstream of TORC1. Furthermore, the ability to suppress TORC1 is conserved in the SKP1/BTB/POZ domain-containing, Whi2-like human protein KCTD11 but not other KCTD family members tested.

Yeast and human cells respond to declining levels of available nutrients to prepare ahead for leaner times. The detailed mechanisms of nutrient sensing are not well understood, but defects in these processes have key roles in diseases such as cancer. The evolutionarily conserved protein complex TORC1 is the control hub for responding to both high and low nutrients, particularly amino acids. We identified yeast Whi2 and the human tumor suppressor KCTD11 as novel suppressors of TORC1 activity in low amino acid conditions, and we investigated the detailed mechanisms for Whi2. Unexpectedly, Whi2 works differently from the usual mechanism where TORC1 is controlled by the SEACIT-Gtr complex (mammalian GATOR1-RAG complex). Furthermore, both the Whi2 and the SEACIT-Gtr pathways work independently and together in parallel to suppress TORC1. For this function, Whi2 requires its binding partners, the yeast protein phosphatases Psr1 and Psr2, which were previously thought to function downstream of TORC1 in amino acid signaling. These studies have important implications for human KCTD11 to help advance the understanding of its pathological role.

CD30 Differential Staining is Useful in Classifying Lymphomas Intermediate between Hodgkin's Disease and Anaplastic Large Cell (Ki1) Lymphoma

AIMS AND BACKGROUND

The authors analyzed the BerH2 reactivity patterns of the tumor cells in 23 Hodgkin's lymphomas (HD), in 13 CD30+ anaplastic large cell (Ki1) lymphomas (ALCL), in two HD with transition to secondary CD30+ ALCL, and in six additional lymphomas intermediate between HD and ALCL.

METHODS

Paraffin blocks of formalin-fixed biopsies were immunostained. Immunostaining was modified by pronase digestion and by microwave assistance.

RESULTS

Hodgkin-Reed-Sternberg (HRS) cells of all 23 Hodgkin's lymphomas were reactive for BerH2, but the reactivity patterns differed: after pronase digestion, HRS cells of 17/23 Hodgkin's lymphomas showed exclusively or at least predominantly cytoplasmic BerH2 reactivity, whereas only four Hodgkin's lymphomas presented with prominent membrane-bound positivity. Microwave processing in 16/23 Hodgkin's lymphomas induced membrane-bound BerH2 positivity in the HRS cells; a minority of five cases retained the distinct cytoplasmic pattern. In contrast, 10/13 ALCLs were characterized by membranous reactions, independent of whether pronase or microwave pretreatment had been applied. The CD30+ ALCLs secondary to HD also showed a tendency towards membranous positivity more than did the antecedent Hodgkin's lymphomas. In the HD/ALCL borderline group, 3/6 cases revealed cytoplasmic BerH2 patterns after pronase digestion and thus were more closely related to HD, whereas 2/6 cases reacted with membranous positivity as did the genuine ALCLs of our series.

CONCLUSIONS

We conclude from these findings that the above modifications in CD30 immunostaining can be helpful in the characterization of lymphomas that constitute a continuous histomorphological as well as phenotypical spectrum between HD and ALCL.

[Retinoblastoma and retinocytoma (retinoma)]

Retinoblastomas are extremely rare withabout half of the cases being hereditary eye neoplasms in young children. They show highly proliferative, CRX-positive undifferentiated tumour cells (occasionally forming rosettes). Staging is performed according to the pTNM classification and the International Retinoblastoma Staging System (IRSS). The diagnostic basis for systemic administration of chemotherapy and/or radiation is postlaminar optic nerve invasion, massive choroidal tumour infiltration, scleral invasion or even extraocular invasion. In cases that are difficult to diagnose, immunohistochemical stains (CRX and Ki67) may be very helpful. Retinocytomas (retinomas) completely lack undifferentiated tumour cell areas, show an exclusive photoreceptor differentiation and an exceptionally low Ki67 index.

[Heterotopic gastric mucosa of the rectum. Case report with literature review]

Heterotopic gastric mucosa is a rare finding in the rectum. Apart from two other hypotheses, a misdifferentiation of entodermal stem cells is the most widely accepted aetiopathogenetic assumption today. Due to acid secretion, the lesions predominantly manifest with hematochezia. Therapeutic options include medicinal therapy and particularly (endoscopic) removal. From the pathologist's point of view a careful evaluation is required also in terms of basically possible dysplastic or malignant changes.

[TTF-1 (8G7G3/1) positive colon adenocarcinoma: diagnostic implications]

Immunohistochemical evaluation of primary and secondary (adeno-) carcinomas of the lung often includes utilisation of two different clones (8G7G3/1 or SPT24) of TTF-1 (thyroid transcription factor 1) antibodies. In a subgroup of adenocarcinomas with a primary site other than the lung a positive reaction of clone SPT24 and also of clone 8G7G3/1 is described. We report on a patient with TTF-1 (clone 8G7G3/1) positive adenocarcinoma of the colon with metastases to the eye and lung and discuss TTF-1 based diagnostic considerations.

[Impressive picture of a melanosis coli after chronic anthraquinone laxative use--is there an increased risk for colorectal cancer?]

We report the case of a 74-year-old female with an extreme picture of melanosis coli of the whole colon after chronic use of anthraquinone laxatives for the treatment of constipation over many decades. Endoscopic work-up revealed an impressive deep black pigmentation of the whole colon mucosa which could be verified by histopathology as a widespread lipofuscin granulation. In addition, various adenomas but no colorectal carcinoma could be detected. The term melanosis coli describes a brown or black pigmentation of the colonic mucosa. Induction of melanosis coli by anthraquinone laxatives and their derivatives can be regarded as verified. The question if melanosis coli predisposes for colorectal neoplasia is discussed controversially. Based on the current literature, an association of melanosis coli between colorectal adenomas, but not colorectal carcinomas, is under discussion but the mechanisms to effect the development of colorectal neoplasia are not completely understood. Considering our case and the current scientific backround, we conclude that due to pharmaceutical side effects of anthraquinone derivatives such as electrolytic shift and water loss in addition to the risk of developing melanosis coli, anthraquinone laxatives should not be used for long-term therapy of constipation.

[Fever and nonspecific pulmonary lesions--a rare differential diagnosis]

HISTORY AND ADMISSION FINDINGS

A 70-year-old woman presented with rapidly increasing weakness, night sweats, progressive dyspnea and daily fever up to 39 C. 30 years before early stage breast cancer had successfully been treated by resection.

INVESTIGATIONS

Blood tests revealed moderate normocytic anemia and a considerable elevation of the serum level of lactate dehydrogenase (LDH). The differential blood count was normal. Chest radiography showed interstitial infiltrates. Computed tomography revealed reticular shadows and ground-glass opacities which on histological examination were attributed to intravascular lymphoma (IVL) of B cell lineage.

TREATMENT AND COURSE

Treatment with eight cycles of the R-CHOP 14 regimen (rituximab, cyclophophamide, doxorubicine, vincristine, prednisone; interval: 14 days) resulted in complete remission with rapid resolution of constitutional symptoms. 7 months later the IVL relapsed, again with fever and an elevation of the LDH level. Bone marrow biopsy revealed intravascular infiltration by lymphoma cells. Salvage treatment with six courses of a methotrexate-containing protocol led to a second complete remission.

CONCLUSION

Nonspecific constitutional symptoms, a large variety of potential clinical presentations and the infrequency of the disease render the ante mortem diagnosis of an intravascular lymphoma difficult. Treatment follows the same principles as in nodal aggressive non-Hodgkin's lymphomas.

Dualism of mixed chimerism between hematopoiesis and stroma in chronic idiopathic myelofibrosis after allogeneic stem cell transplantation

Scant knowledge exists concerning lineage-restricted mixed chimerism (mCh) after allogeneic peripheral blood stem cell transplantation (PSCT) in patients with chronic idiopathic myelofibrosis (CIMF). Following a sex-mismatched PSCT, a combined immunopheno- and genotyping by fluorescence in-situ hybridization (FISH) was performed on sequential bone marrow (BM) biopsies at standardized intervals. Results were compared with PCR analysis of corresponding peripheral blood samples in five patients. According to FISH, pretransplant specimens revealed a gender congruence of more than 99%, while in the first three months the total BM exhibited a persistent fraction of host cells (30% to 40%) with a tendency to decline after about one year. It is noteworthy that the majority of endothelial cells maintained a recipient origin, whereas CD34+ progenitors and especially CD61+ megakaryocytes exhibited only very few host-derived cells. In keeping with the prevalence of donor cells in the hematopoietic compartment, PCR analysis of peripheral blood cells displayed a non-significant degree of mCh. In conclusion, according to FISH and PCR analysis, successful PSCT in CIMF results in an almost complete chimeric (donor-derived) state of the hematopoietic cell population. The non-transplantable stromal compartment includes the vascular endothelium with a predominance of recipient cells. The minimal mCh of this population implies probably a donor-derived origin (endothelial progenitor cells).

[Two cystic retroperitoneal lesions mimicking adrenal cysts]

Adrenal cysts are uncommon lesions and most of them are found incidentally during abdominal imaging. We report on two benign extraadrenal lesions mimicking adrenal tumors in abdominal imaging. The histopathological investigation of the lesions revealed a foregut duplication cyst of the lesser gastric curvature and an epithelial inclusion cyst (epidermoid cyst) in an intrapancreatic accessory spleen respectively.

Dynamics of bone marrow changes in patients with chronic idiopathic myelofibrosis following allogeneic stem cell transplantation

Scant knowledge exists about the dynamics of fibro-osteosclerotic bone marrow (BM) lesions and regeneration of hematopoiesis following allogeneic peripheral stem cell transplantation (SCT) in chronic idiopathic myelofibrosis. Therefore, an immunohistochemical and morphometric study was performed on BM biopsies in 20 patients before and at standardized intervals (days 30 through 384) following SCT. In responding patients, a total regression of the pretransplant increased fibrosis was completed in the posttransplant period after about six months, while the extent of osteosclerosis did not change significantly during observation time. The quantity of CD61+ megakaryocytes including precursors was strikingly variable after SCT and, by using planimetric methods, atypical microforms exhibiting a dysplastic aspect could be demonstrated. These anomalies may be responsible for posttransplant thrombocytopenia. CD34+ progenitor cells were increased before transplantation, however, their number declined rapidly to normal values in responding patients. Nucleated erythroid precursors revealed a decreased amount before and after SCT accounting for anemia. Large clusters of this cell lineage indicated an initial hematopoietic reconstitution comparable with the expansion of the neutrophil granulopoiesis. Proliferative activity and apoptosis showed an increase until one year after SCT that implied a still regenerating hematopoiesis in keeping with an enhanced cell turnover.

ETV6–NTRK3 gene fusion in a secretory carcinoma of the breast of a male-to-female transsexual

Secretory carcinomas of the breast were first described as "juvenile carcinoma" by McDivitt and Stewart in a cohort of children. This term has been replaced by the term "secretory breast carcinoma", because the entity can occur at any time of life. Carcinoma of the male breast is uncommon and accounts for approximately 1% of all cancers in men. Recently, it has been reported that human secretory breast carcinoma expresses the ETV6-NTRK3 gene fusion that was previously cloned in pediatric mesenchymal cancers. We present the case of a 46-year-old male-to-female transsexual in whom a secretory breast carcinoma was an incidental finding. As confirmation of the histopathological diagnosis we detected the novel ETV6-NTRK3 gene fusion in this tumor.

Regeneration of heart muscle tissue: quantification of chimeric cardiomyocytes and endothelial cells following transplantation

Persuasive evidence has been recently provided that adult bone marrow (BM) cells exert greater plasticity than previously assumed. This review is focused on the quantification of mixed chimerism (mCh) in the hearts (cardiomyocytes and endothelial cells) of patients after orthotopic heart to heart transplantation (HHT) in comparison to full (unmanipulated) allogeneic BM and peripheral blood stem cell (PBSC) transplants. Following a sex-mismatched transplantation constellation heart muscle tissue obtained at autopsy was examined. Evaluation of mCh was most often performed by immunophenotyping combined with fluorescence in-situ hybridization (FISH) applying x- and y-chromosome-specific DNA probes. When comparing our data with the results of former studies that were regularly based on the detection of the y-chromosome alone, the quantity of chimeric cardiomyocytes after HHT ranged from 0% to 9%. On the other hand, after full BM transplantats (chimeric) cardiomyocytes of donor-type origin appeared at an incidence between 0.23% to 6.4%. These disturbing inconsistencies were assumed to be related to methodology: the restriction to the y-chromosome, disregard of the plane of section (detection sensitivity ranging between 35% and 67%) and state of tissue preservation (cadaver hearts). Therefore, when strictly applying dual color FISH and limiting the recognition of chimeric cardiomyocytes and endothelial cells to the presence of two distinctive signals detection sensitivity was significantly enhanced. Contrasting a total congruence with the genotyping in control specimens of normal cadaver hearts, a striking disparity in the extent of mCh was found depending on the different modes of transplantation. After allografting with PBSC a considerably low incidence (1.6%) of chimeric cardiomyocytes was determined contrasting with 5.3% of donor-derived cells after full BM transplants. Following HHT host-type endothelial cells (16.2%) of the intramural and subepicardial vessel walls were more often encountered than following BM and PBSC allografting. These findings are in keeping with the assumption of a sprouting and migration of vascular structures into the donor heart from the site of surgical aligment and injury between retained host and donor atrial walls. When considering the other methods of transplantation (BM, PBSC) the data on chimeric endothelial cells support the hypothesis of a common hemangioblast. Concerning the cardiomyocytes it seems most reasonable to assume that primitive mesenchymal stem cells of the BM play a pivotal role in the development of mCh. This phenomenon is more extensively expressed than previously expected and may be related to an enforced repair of the damaged myocardium during the post-transplant period as the sequel of myeloablative (cardiotoxic) conditioning.

Das Plattenepithelkarzinom der Ohrmuschel

METHODS

Data for all patients with ear malignancies being operated in our department between August 1988 and March 2001 were retrospectively analyzed for tumor localisation, stage, biometric data, anesthesiological risk factors, therapy and recurrence of the disease.

RESULTS

Thirty of 79 patients (29 male, one female; average age 77.2 years, range 54-99 years) with cutaneous malignancies of the external ear were diagnosed as SCC ( n=32 SCC). A total of 17 SCC were smaller than 2 cm, 12 were between 2-5 cm, and three were larger than 5 cm. Only two patients had regional nodal disease, none had distant metastases. The anesthesiological risk was estimated according to the recommendations of the American Society of Anesthesiologists (ASA); 16/30 patients were classified as group 3 or 4, having severe general disease with a decrease in vitality or even vital risks. A total of 24 SSC were primarily operated under local anesthesia. Depending on histology, localisation and size of the SCC local excision, partial or total removal of the auricle was performed. In the remaining 8/32 cases, the primary intervention was performed under general anesthesia, mostly in combination with an ipsilateral neck dissection and a superficial parotidectomy. In 8/32 cases, the SCC had to be re-operated after primary R1 resection. Altogether, eight patients received radiotherapy. In 5/32 cases there was a recurrence of the disease. The average follow-up period of the 13 patients who are still alive is 50 months (17-113). One patient died as a result of the metastasized SCC and 16 patients died due to other diseases.

DISCUSSION

Considering the high age and the age-associated general diseases of the patients with SCC of the auricle, differentiation between a radical concept of therapy and its risks and possible therapy-related damage is important. Therefore, individual concepts such as partial removal of the pinna without neck dissection and parotidectomy for the N(0) stage are justified if relevant anesthesiological risk factors have to be taken into account.

Lymphknotenschwellung in der Leiste

A 65 year old female patient was admitted to our hospital with unspecific symptoms and a lump in the right groin which raised suspicion of a malignant lymphoma. Histologically a follicular dendritic reticular cell tumor was found. Because there are aggressive forms of this tumor and no established standard therapy, we decided to treat her with surgery followed by a combined radio- and chemotherapy. Despite this treatment 16 months after the first diagnosis a relapse occurred with a metastasis of the follicular dendritic cell tumor in the lung. The metastasis was resected surgically. The optimal management of this kind of tumor is not known.

[A bone-destroying tumor of the maxilla. Reparative giant cell granuloma or brown tumor?]

Brown tumors are focal bone lesions caused by an increased osteoclastic activity and fibroblastic proliferation within a primary or more rarely secondary hyperparathyroidism. They are named after their typical brown hemorrhagic stroma with its also typical giant cell formations. We report the case of a 31-year-old pregnant patient with a rapidly growing tumor of her left maxilla whose first symptoms during pregnancy mimicked chronic sinusitis. After swelling of the cheek, diplopia, and recurrent epistaxis appeared, she was referred to our Department for further diagnostics. After CT scan, biopsy was performed under the presumption of a malignant process with the surprising histological result of a reparative giant cell granuloma. At the same time, hyperthyroidism and nodular goiter were diagnosed and further endocrinological examinations were planned. Not until a parathyroid adenoma was diagnosed after urgent operation of the maxillary process (loose molar teeth and displacement of the left bulbus) could the tumor be interpreted and detected within this context of primary hyperparathyroidism as a brown tumor. The brown tumor should be taken into consideration as a rare differential diagnosis of a bone-destroying process of the facial bones. We discuss the clinical signs, diagnostics, and therapy for this case as well as the relevant literature. The reparative giant cell granuloma represents an important differential diagnosis and cannot be distinguished from a brown tumor by histological examination or radiological findings without complete information about the clinical signs and the endocrinological status of the patient.

Increased expression of metallothionein in inflammatory bowel disease

OBJECTIVE

Metallothioneins (MT) are cytoprotective against the damaging effects of oxygen-derived free radicals. Therefore MT may be involved in defence mechanisms to counter Crohn's disease (CD) and ulcerative colitis (UC).

MATERIALS

107 routinely processed tissue samples from 22 patients with CD and 48 patients with UC were tested with the monoclonal anti-MT antibody E9.

METHODS

Immunohistochemistry was used to assess MT staining in a semiquantitative manner. Chi-square test was used for statistical analysis.

RESULTS

MT overexpression was found in the fibroblasts of all ulcerative and/or fissural lesions in UC and CD. MT overexpression in intestinal epithelial cells of 40% of UC and CD lesions correlated significantly with the grade of inflammation.

CONCLUSIONS

MT-immunoreactivity in fibroblasts supports a protective role for MT in inflammatory bowel disease. It remains unclear whether MT overexpression in epithelial cells is also important in this protection.

Haemangiopericytoma of the nasal cavity

Haemangiopericytomas (HPC) are rare vascular tumours originating from a pericytes, a term coined by Zimmermann to refer to the main location of this cell line in the pericapillary connective tissue. HPC may arise in any part of the body. We report a 29-year-old man with a histologically proven nasal haemangiopericytoma-like tumour. The lesion was embolised through the ophthalmic artery before it was removed surgically. The main symptoms of nasal HPC are epistaxis and obstruction of the nose. Malignant and benign clinical courses have been described. Local recurrence and metastases may be observed years after initial diagnosis.

[Endoscopic excision of extra-adrenal pheochromocytomas (paragangliomas)]

We describe the successful endoscopic removal of six extra-adrenal pheochromocytomas in three patients. One neoplasia was located retrocavally, two between the aorta and vena cava, two by the para-aortal, and one by the parailiacal. The tumors were removed by the posterior retroperitoneoscopic or by the anterior laparoscopic approach, respectively. The intraoperative and postoperative courses were uneventful.

[Detection of endometriosis during cesarean section for HELLP syndrome in the 32nd week of pregnancy]

The rare case of a decidualized endometriosis of the appendix vermiformis is reported in a woman who developed HELLP syndrome during the 32nd week of a twin pregnancy. Cesarean section and simultaneous appendectomy were performed. An inspection of the appendix should always be carried out if an endometriosis-associated anamnesis is known. No pathophysiological correlations between the HELLP syndrome and the endometriosis of the appendix vermiformis could be found.

Keyhole limpet hemocyanin for carcinoma in situ of the bladder: a long-term follow-up study

OBJECTIVE

Keyhole limpet hemocyanin (KLH) is a nonspecific immunomodulator, demonstrated to be clinically effective in superficial bladder cancer. The present study investigated the clinical efficacy of intravesical KLH in patients with carcinoma in situ (CIS) with a long-term follow-up.

METHODS

Thirteen patients with CIS grade III were treated with intravesical instillations of KLH, 20 mg for 6 weeks, then monthly for 1 year and bimonthly for 2 subsequent years. Patients not responding to 2 courses of KLH were treated with bacillus Calmete-Guérin (BCG, 81 mg Connaught strain).

RESULTS

The follow-up period ranged from 12 to 84 months. Two patients were free of tumor after KLH instillations with a follow-up of 66 and 82 months, respectively. All patients who did not respond to the primary KLH course, but to the 'rescue' instillation of BCG, experienced recurrences after 42, 48, 56 and 60 months after the first KLH instillation treatment. Three patients with recurrent CIS and who were not cystectomized had recurrences after prolonged remission (4-5 years). Patients progressing despite KLH and BCG instillations underwent cystectomy.

CONCLUSIONS

KLH demonstrates efficacy and induces long- term remissions against CIS in a limited number of cases. In the present study, most patients with CIS progressed over time whatever the substance instilled, whether KLH or BCG. CIS remains a very aggressive neoplasm requiring a lifelong follow-up. Further studies are necessary to define the precise role of KLH in patients with CIS.

[Inflammatory pseudotumor of the nasal septum]

An inflammatory pseudotumor occurs unifocally and is a benign tumor that was initially described in the lung. In the present case report a 24-year-old woman experienced progressive nasal obstruction because of an abnormality of the nasal septum. A cauliflower-like tumor of the anterior region of the septum cartilage was seen macroscopically and was completely resected. This was diagnosed histologically as an inflammatory pseudotumor. The literature is reviewed and differential diagnoses discussed. Various therapeutic procedures are noted, but the treatment of choice is complete resection of tumor.

Descriptive epidemiology of small intestinal malignancies: the German Cancer Registry experience

In the first population-based analysis of certain epidemiologic features of primary malignancies of the small intestine in Germany, we used data from the Saarland Cancer Registry (1982-1993) and from the former National Cancer Registry of the German Democratic Republic (1976-1989). The age-standardized incidence rates for ages 0-74 years is 3.3-6.2 per million per year. The average incidence rates of the federal state Saarland are for men about 1.3 times and for women about 1.4 times the rate of the former German Democratic Republic. After the age of 30 years, the incidence rates increased with increasing age. Incidence rates for carcinoids levelled off after the age of 54 years. Rates for men were 35-40% higher than for women after adjusting for age. The risk for carcinomas, malignant carcinoids and malignant lymphoma were higher for men than for women.

Cytokeratin and neurofilament protein staining in Merkel cell carcinoma of the small cell type and small cell carcinoma of the lung

Merkel cell carcinoma (MCC) has a small cell variant, indistinguishable in hematoxylin-eosin sections from metastatic small cell carcinoma of the lung (SCCL). To investigate whether intermediate filament expression is helpful in this distinction, 17 MCCs of the small cell type were examined for cytokeratin, as well as neurofilament protein immunostaining, and compared with 59 intermediate-type MCCs and 22 SCCL. With a pan-cytokeratin cocktail (cytokeratin 1-8, 10, 13-16, 19), most (39 of 55) intermediate-type tumors and, more important, 11 of 16 cases of the small cell variant exhibited focal paranuclear staining with dot-like positivity, crescentic positivity, or both. A combined focal (dot-like/crescentic) and diffuse cytoplasmic pan-cytokeratin staining was seen in additional 8 of 55 intermediate and 4 of 16 small cell MCCs. Cytokeratin 20 also evoked focal cytoplasmic staining and occasionally focal and diffuse positivity in the MCCs, irrespective of the subtype. Exclusively diffuse cytokeratin 20 patterns did not occur. Conversely, most SCCL showed a diffuse expression of pancytokeratin, and all cases remained cytokeratin 20 negative. When neurofilament protein was applied, approximately half of the MCCs (25 of 40), including 7 of 11 of the small cell variant, were positive, whereas all SCCL were negative. In conclusion, the cytokeratin and neurofilament protein patterns of small cell MCCs are identical to the pattern of intermediate MCCs but differ from the profile of SCCL, which may help in the differential diagnosis.

Merkel cell carcinoma of the eyelid: histological and immunohistochemical features with special respect to differential diagnosis

BACKGROUND

Merkel cell carcinomas (MCC) not infrequently involve the periorbital region and the eyelids. Clinically, they are relatively characteristic but often unsuspected. Histologically, MCC are often misdiagnosed as lymphoma, melanoma, or metastatic small cell carcinoma of the lung (SCCL).

METHODS

We present clinical, histological, and immunohistochemical data on six eyelid cases (all females; age 63-102 years; one with concomitant CLL) from our files of 77 MCC with special respect to differential diagnosis. For comparison, 22 SCCL were analyzed. Immunohistochemistry was done with antibodies against pan-cytokeratin (pan-CK), cytokeratin-20 (CK-20), neurofilament protein (NF), neuron-specific enolase (NSE), chromogranin (CHR), and S100 protein (S100).

RESULTS

Morphologically, five of six MCC were prototypic, one was of the small cell variant. Immunohistochemically, dot-like positivities for pan-CK and CK-20 were seen in all six MCC, and for NF in five tumors. None of the 22 SCCL stained positively for CK-20 or NF but 21/22 cases were positive for pan-CK. Only 1/21 SCCL showed dot-like patterns for pan-CK; 20/21 reacted diffusely. All MCC and 13/22 SCCL displayed CHR-positive cells. All MCC and all SCCL were positive for NSE and negative for S100.

CONCLUSIONS

Dot-like positivities for CK-20 or NF are important to prove MCC and to exclude SCCL in clinically and morphologically doubtful cases. Dot-like positivities for pan-CK favor MCC, but do not always exclude SCCL. NSE and CHR are of no value for the differential diagnosis of MCC and SCCL. Melanoma and lymphoma are ruled out by negativity for S100 and pan-CK, respectively.

[Surgery of primary unilateral adrenal gland tumors--results of 154 patients]

Surgical resection of adrenal neoplasias with endocrine activity is principally indicated. In adrenal neoplasias without endocrine activity, surgical removal is indicated in relation to tumor size. Surgical access and extent of resection are the major problems related to adrenal surgery. From 1980 to 1996, in 154 patients (62 m, 92 f) primary and unilateral adrenal tumors (139 benign, 15 malign) were resected. 93 resections were performed transperitoneally, 13 extraperitoneally, and 48 retroperitoneoscopically. Subtotal adrenal resections were performed in 23 benign tumors smaller than 4 cm. Perioperative lethality was 0%, morbidity was 31.8%. Malignancy was correlated to tumor size: In 114 tumors smaller than 5 cm, no malign neoplasia was found, whereas in 40 tumors larger than 5 cm, 15 specimen were malign. Operating time of the retroperitoneoscopic method was significantly longer than of open procedures (p < 0.05). Postoperative analgotic medication was significantly reduced after endoscopic surgery compared to transperitoneal or extraperitoneal surgery (p < 0.0001). No tumor recurrences occurred after subtotal adrenal resections (mean follow up: 5.7 [1.3 years]). In patients with adrenal carcinomas, 5-year-survival was approximately 15%. In adrenal neoplasias smaller than 5 cm, malignancy is extremely rare. Therefore, less aggressive surgery with a lower morbidity (extraperitoneal approach) and reduced postoperative pain (retroperitoneoscopic approach) including function preserving resection is indicated in these lesions. Due to the high incidence of malignancy, adrenal tumors larger than 5 cm should principally be treated by conventional transperitoneal surgery.

[Differential diagnosis of cystic adnexa processes. A comparison of the value of sonography, puncture cytology and color and biochemical biopsy analysis with histology]

The histological diagnoses of 109 cystic adnexal masses were compared with the results of ultrasound examination, color, cytology and biochemical analyses of cystic fluid. In cases with suspicious results by ultrasound examination most of the malignant tumors but only a small number of benign cystic masses were found. Macroscopic and cytologic examinations gave no further informations. By biochemical analyses functional cysts could be detected with 86% of sensitivity and 100% of specificity by a combination of estradiol, progesterone and Ca 12-5. Endometrioma and malignant tumors could be separated from other adnexal masses (specificity 95%, sensitivity 100%) with a combination of Tag 72-4 and CASA.

How to differentiate between T-cell-rich B-cell lymphoma and lymphocyte-predominant Hodgkin's disease. Evidence for the value of MB1 and 4KB5 immunostaining

Striking morphological similarities exist between T-cell-rich B-cell lymphoma and lymphocyte-predominant Hodgkin's disease (Hodgkin's paragranuloma), making the distinction between them extremely difficult. Immunohistochemistry provides a means of overcoming this difficulty. Immunostaining with UCHL1, L26, MB1, and 4KB5 was performed on five T-cell-rich B-cell lymphomas and 11 Hodgkin's paragranulomas (7/11 nodular, 4/11 diffuse). L26 stained the tumour cells not only of T-cell-rich B-cell lymphomas, but also of L+H Hodgkin's disease. In contrast, MB1 as well as 4KB5 identified all of the neoplastic cells in 3/5 T-cell-rich B-cell lymphomas, but did not react with the L+H cells in 8/11 Hodgkin's paragranulomas. Some overlap of staining patterns became apparent in the remaining cases, with 2/5 T-cell-rich B-cell lymphomas showing the MB1+/4KB5+ phenotype in a tumor cell subset only. Similarly, in 3/11 Hodgkin's paragranulomas, some MB1/4KB5-positive L+H cells occurred in addition to MB1/4KB5-negative L+H cells. These cases, nevertheless, could be distinguished from one another by the numbers of MB1/4KB5-positive background lymphocytes, which were scanty or absent in T-cell-rich B-cell lymphomas and more numerous in Hodgkin's paragranulomas.

Variability of differentiation patterns in xenotransplanted spindle cell sarcomas: a histomorphological, immunohistochemical, and ultrastructural study

Three leiomyosarcomas, 3 nerve sheath sarcomas, 1 rhabdomyosarcoma, and 1 sarcoma not otherwise classifiable with 17 of their xenografts, grown on nude mice, were analyzed to assess the degree of concordance between histomorphology, immunohistochemistry, and ultrastructure in spindle cell sarcoma xenograft differentiation. Histomorphology was inconclusive or misleading in 4/8 sarcoma strains and immunohistochemistry in 4/8 originals and in 10/17 xenografts, although specific patterns had been identified ultrastructurally. Electron microscopy was superior to immunohistochemistry and histomorphology in spindle cell sarcoma differential diagnosis. A further purpose of this study was to clarify whether spindle cell sarcoma xenografts retain the morphological characteristics of their primaries. Histomorphological features of the primaries were preserved over all passages, whereas the immunohistochemical marker profiles as well as the ultrastructural phenotypes changed in 14/17 xenografts and in 8/17 xenografts, respectively. Moreover, unusual bidirectional or tridirectional patterns of differentiation were identified ultrastructurally with leiomyomatous as well as Schwann cells occurring side by side and with MFH-like areas in 5/17 xenotransplants. These findings suggest genetic instability of tumor cells and may be important in the consideration of mesenchymal differentiation pathways.

Immunohistological findings in patients with superficial bladder carcinoma after intravesical instillation of keyhole limpet haemocyanin

OBJECTIVE

To determine whether keyhole limpet haemocyanin (KLH) instilled intravesically improves the local cellular response within the bladder wall of patients suffering from superficial bladder carcinoma.

PATIENTS AND METHODS

Twelve patients (10 men and two women, mean age 67 years, range 42-85) with superficial carcinomas of the bladder were treated for 6 consecutive weeks and then monthly for 1 year with 20 mg KLH in 20 mL saline instilled intravesically after complete resection of the tumours. Biopsies were taken for immunohistochemical examination before treatment and again 6 weeks, 3, 6 and 9 months after treatment. Six patients with no evidence of cystitis or malignant bladder disease acted as a control group. Immunofluorescent staining of the biopsies was performed using monoclonal antibodies to the T-cell markers CD4 and CD8, and to CD14 (monocytes), CDw15 (granulocytes), CD19 B-cells (Pan-B), CD68 (macrophages) and HLA-DR. Anti-KLH antibody-producing plasma cells were detected using a standard technique. A semiquantitative analysis of locally infiltrating cell types was performed.

RESULTS

After treatment with KLH the increase of CD8+ suppressor cells was less pronounced than that of CD4+ helper cells. The T-helper/inducer to T-suppressor/cytotoxic cell ratio thus altered from 0.8:2.0 before treatment to 1.6:2.3 afterwards. Hence, the number of T-helper cells had increased considerably, whereas there was only a moderate increase in the number of T-suppressor cells. This cellular ratio could be detected for 9 months after KLH therapy. The numbers of activated HLA-DR+ immune cells in the submucosa and among urothelial cells also increased after KLH instillation. The degree of mononuclear cell infiltration of the submucosa increased considerably, but granulocyte infiltration was only moderate. Lymph follicles with enhanced B-lymphocyte counts were also detected.

CONCLUSION

Immune-cell infiltration into the urothelium and enhanced activation (expression of class II antigens) suggests distinct processes of cellular antigen recognition, which could be detected for up to 9 months after the beginning of KLH therapy. This may represent a basic functional mechanism of KLH therapy.

Effect of keyhole limpet hemocyanin (KLH) and bacillus Calmette-Guérin (BCG) instillation on carcinoma in situ of the urinary bladder

Patients with histologically verified carcinoma in situ (CIS) of the urinary bladder (13 primary and 8 secondary CIS) were treated with intravesical instillations of Keyhole Limpet Hemocyanin (KLH) (20 mg KLH weekly for 6 weeks, then monthly for 1 year or bimonthly for 2 subsequent years. Patients, non-responding to 2 courses of KLH were then treated with regular Bacillus Calmette-Guerin instillations (120 mg BCG-Connaught strain). The follow-up period ranged from 10 to 54 months (mean 23.5 months). 7 patients (33%) were free of tumor after the first therapeutical KLH course and 4 patients (19%) presented a complete-remission after the second KLH course (total primary response: 52%). 5 patients (24%) remained free of tumor during the established follow-up period (mean 31.7 months) and no evidence of further tumor progression occurred in patients after two courses of KLH treatment. However, 2 patients (9.5%) had to be cystectomized after KLH instillations because of progressive disease or tumor recurrence. 8 patients (38%) had to be radically cystectomized because of CIS persistence or progression after KLH and subsequent BCG treatment. Altogether 9 patients (42.8%) presented long-term remissions, with a mean duration of 31.3 months. Instillations of KLH did not induce major side effects; however, instillations of BCG caused severe dysuria in 60% and fever in 40% of patients.

T-cell-rich B-cell lymphoma and lymphocyte-predominant Hodgkin's disease: two closely related entities?

T-cell-rich B-cell lymphoma (TCRBCL) is a recently described variant of non-Hodgkin's lymphoma. It may arise de novo or secondary to follicular lymphoma and large B-cell lymphoma. We present here seven cases of TCRBCL to emphasize a peculiar relationship to lymphocyte-predominant Hodgkin's disease. Morphologically, the neoplastic populations of all TCRBCLs, in addition to centroblast-like and immunoblast-like cells, comprised a few L+H-like elements. These neoplastic cells were all regularly scattered in a majority of reactive small T-lymphocytes as well as histiocytes. Moreover, tumour cells of TCRBCL, including the L+H-like elements of TCRBCL, expressed LCA and L26 but did not stain for Leu-M1 and BerH2, as is the case with the Reed-Sternberg cell L+H variant of lymphocyte-predominant Hodgkin's disease. Furthermore, the L26 immunoreaction in one of the cases, which otherwise presented as typical TCRBCL, disclosed a small subcapsular area resembling nodular paragranuloma because some few foci consisting of mature B lymphocytes with occasional L+H-like elements were seen. This also holds true for a second of the TCRBCLs presented that obviously coexisted with recurrent Hodgkin's paragranuloma 10 years after the primary manifestation. These findings indicate a close connection between TCRBCL and lymphocyte-rich Hodgkin's disease, and it may even be speculated as to whether TCRBCL represents merely a phenotypically different manifestation of this Hodgkin's subtype. Although the data presented here will not provide sufficient proof of this hypothesis, it seems clear that the nosology of TCRBCL in the context of current lymphoma classifications requires further elucidation.

Deep venous thrombosis and pulmonary artery embolism in high-grade non Hodgkin's lymphoma: incidence, causes and prognostic relevance

To analyse incidence, risk factors, causes and prognostic significance of venous thromboembolism (VTE) in high-grade non-Hodgkin's lymphoma (HG-NHL) a prospective clinical trial (N = 593), also undertaken to analyse other aspects of HG-NHL, a study of haemostasis (N = 25) and a post-mortem analysis (N = 70) were performed. Clinical analysis documented a 6.6% incidence of VTE, and 77% of all cases occurred before or within the first 3 months of chemotherapy. Ann Arbor stage IV and B-mediastinal clear cell histology were risk factors for VTE, while rapid changes in tumour load or application of consolidation chemotherapy were not. Vessel compression by HG-NHL was the leading cause of VTE, whereas a significant (paraneoplastic or chemotherapy-induced) thrombophilic state was not disclosed by haemostatic tests. While VTE-related fatality was found to be low in the clinical trial (1.7%) and at necropsy (8.5%), the occurrence of VTE was associated with an unsatisfactory response of HG-NHL to chemotherapy and a high incidence of treatment-related mortality due to diffuse alveolitis. Thus, fatal VTE in HG-NHL is rare, but VTE is associated with an unfavourable clinical course of HG-NHL.

Immunohistochemical detection of estrogen and progesterone receptors in endometriotic tissue. A comparative study of paraffin embedded and fresh frozen tissues

30 formalin-fixed and paraffin embedded and 20 fresh frozen samples of endometriotic tissue were analysed immunohistochemically for the concentration of estrogen and progesterone receptors. In the formalin-fixed and paraffin embedded group only 37% of the samples were estrogen receptor positive whereas 63% were receptor negative. In contrast, we found that 67% of the samples had a positive progesterone receptor status. In the fresh frozen group 60% of endometriotic tissues were estrogen receptor positive and 75% of the tissues had a positive progesterone receptor status. We could not find any correlation between the site or severity of the endometriosis or the hormonal receptor status. We were able to demonstrate that the immunohistochemical detection of hormonal receptors in endometriotic tissues is possible and that better results were obtained if fresh frozen rather than formalin-fixed and paraffin embedded tissues were analyzed.

Melanotic neuroectodermal tumor of infancy (MNTI) in the epididymis. A case report with immunohistological studies and special consideration of malignant features

Melanotic neuroectodermal tumors of infancy (MNTI) are uncommon, usually benign neoplasms, most frequently found in the maxilla. These tumors are extremely rare in the epididymis. Only 18 cases with this site of origin are documented. We report on the third epididymal MNTI with some morphological characteristics of malignancy but favorable clinical outcome. The 2 cm large tumor of a 6-month-old male infant showed large epitheloid cells in the center and small neuroblastoma-like cells at the periphery. Despite invasion of lymphatics there is no evidence of relapse or metastases during 4 years of follow-up. Immunohistochemically, the large tumor cells were distinctly positive for cytokeratin, vimentin, GFAP, the melanoma marker NKI-C3, NSE, and S100. The small tumor cells were only slightly positive for GFAP, NKI-C3, NSE, and S100 but they were negative for cytokeratin and vimentin. Neurofilament and chromogranin could not be proved in the tumor.

[Endometriosis in retroperitoneal lymph nodes]

This is a case report on an endometriosis in retroperitoneally situated lymphatic nodes in a 29-year-old patient. The patient had a cervical carcinoma FIGO Ib and was treated surgically by radical hysterectomy after Wertheim-Meigs-Okabayashi with pelvic lymphonodectomy. Endometriosis was found in two lymphatic nodes of the retroperitoneum. The patient had no anamnesis or clinical symptoms of endometriosis. Endometriosis could also not be found in any other parts of the abdomen.

Well-differentiated (oncocytoid) neuroendocrine carcinoma of the larynx with multiple skin metastases: a brief report

A 63-year-old woman presented with a history of increasing dysphagia of about two weeks duration. Laryngoscopy revealed a nonulcerated supraglottic epitheliomatous lesion that morphologically appeared well-differentiated and distinctly oncocytoid. Although the tumour lacked any criteria for malignancy such as cellular atypia, pleomorphism or necroses, it recurred twice after primary surgery and later gave rise to multiple painful skin metastases. The diagnosis of an oncocytoid differentiated neuroendocrine carcinoma of the larynx (laryngeal carcinoid) was made. Misinterpretation of laryngeal carcinoids is common, but can be avoided if one is familiar with this rare variant of laryngeal neoplasms.

The association of pulmonary CMV infection with interstitial pneumonia after bone marrow transplantation. Histopathological and immunohistochemical findings in 104 autopsies

Lung tissue of 104 necropsies was studied by routine (HE) histology, by immunohistochemistry and partly by in situ hybridization in order to explore the association of pulmonary cytomegalovirus (CMV) infection and interstitial pneumonia (IP) after allogeneic bone marrow transplantation. IP was detected in 59 of 104 patients (56%). 12 of these (20% of the IP cases) presented as CMV-IP. No evidence of a CMV infection was obtained in the remaining 47 IP. Immunohistochemistry did not improve the CMV detection essentially over the results of routine (HE) analysis of viral inclusions. In situ hybridization performed on frozen sections of 21 cases turned out to be more sensitive than routine histology and immunohistochemistry, detecting active as well as latent CMV infections. However, the clinical relevance of latent infections, as disclosed by positive hybridization results in the absence of nuclear inclusions as well as immunohistochemical positivities, seems to be low, because latent infections typically were not found to be associated with IP.

Pheochromocytoma of the urinary bladder

A case of a pheochromocytoma of the urinary bladder is reported which was treated preoperatively with alpha-receptor-blocking agents. The tumor was operated transurethrally, followed by partial cystectomy.

[Splenic cysts. Their morphology, diagnosis and therapy]

Over a 10-year period, nine patients (four men, five women, mean age 27 years) underwent surgery for splenic cysts (six epidermoid cysts, two mesothelial cysts and one pseudocyst). Six patients had had suggestive clinical symptoms, but, in the other three, the cysts were only discovered by chance on ultrasound scan. Three of the patients with epidermoid cysts had raised serum concentrations of the tumour markers carcinoembryonic antigen (CEA) or carbohydrate antigen (CA 19-9. All six benign epidermoid cysts contained immunohistochemically demonstrable CEA and/or CA 19-9 in the inner epithelial layer, implying a mesothelial origin for these cysts. In five cases the splenic cysts were completely extirpated (splenectomy in two, hemisplenectomy in one, enucleation in two); in four cases cyst resection was performed, leaving part of the cyst adherent to the spleen. In one of these four patients, a 4 cm cyst persisted postoperatively in the hilus of the spleen, but has remained unchanged over an 8-year period. Splenic cysts are usually benign, despite the presence of tumour markers in the cyst wall, and do not require removal. The only indications for surgical intervention are complications (e.g. rupture), symptomatic cysts or asymptomatic cysts with an increased risk of rupture (diameter greater than 5 cm). The very rare parasitic and infective forms must always be surgically sterilized.

[Primary lymphatic dysplasia in a newborn infant]

We describe a case of primary lymphatic dysplasia in a newborn, presenting with lymphedema, chylothorax, and chylous ascites. Malfunction of the lymphatic system, which is supposed to cause this rare disorder, could also be responsible for a number of cases of non-immunologic hydrops fetalis.

[Spontaneous remission in disseminated histiocytosis X]

An 8 months old girl presented with biopsy-proven, disseminated histiocytosis X affecting at least two organ systems. Within one year there was spontaneous regression of the disease lasting for 10 years until today. Considering this case and others from literature the necessity of aggressive chemotherapy in selected cases is discussed.