Pancreatic-polypeptide-producing apudoma of the liver

DHODH-mediated ferroptosis defence is a targetable vulnerability in cancer

Ferroptosis, a form of regulated cell death that is induced by excessive lipid peroxidation, is a key tumour suppression mechanism1-4. Glutathione peroxidase 4 (GPX4)5,6 and ferroptosis suppressor protein 1 (FSP1)7,8 constitute two major ferroptosis defence systems. Here we show that treatment of cancer cells with GPX4 inhibitors results in acute depletion of N-carbamoyl-L-aspartate, a pyrimidine biosynthesis intermediate, with concomitant accumulation of uridine. Supplementation with dihydroorotate or orotate-the substrate and product of dihydroorotate dehydrogenase (DHODH)-attenuates or potentiates ferroptosis induced by inhibition of GPX4, respectively, and these effects are particularly pronounced in cancer cells with low expression of GPX4 (GPX4low). Inactivation of DHODH induces extensive mitochondrial lipid peroxidation and ferroptosis in GPX4low cancer cells, and synergizes with ferroptosis inducers to induce these effects in GPX4high cancer cells. Mechanistically, DHODH operates in parallel to mitochondrial GPX4 (but independently of cytosolic GPX4 or FSP1) to inhibit ferroptosis in the mitochondrial inner membrane by reducing ubiquinone to ubiquinol (a radical-trapping antioxidant with anti-ferroptosis activity). The DHODH inhibitor brequinar selectively suppresses GPX4low tumour growth by inducing ferroptosis, whereas combined treatment with brequinar and sulfasalazine, an FDA-approved drug with ferroptosis-inducing activity, synergistically induces ferroptosis and suppresses GPX4high tumour growth. Our results identify a DHODH-mediated ferroptosis defence mechanism in mitochondria and suggest a therapeutic strategy of targeting ferroptosis in cancer treatment.

Primary Hepatic Neuroendocrine Tumor: What Do We Know Now?

Primary hepatic neuroendocrine tumors (PHNETs) are rear neoplasm. Diagnosis is an evolution, and requires a systematic clinical exclusion with histological confirmation. Treatment is surgical with excellent prognosis, and a long-term follow-up is required due to high tumor recurring rate. Knowledge from this species of tumor remains limited due to paucity of cases. This article elaborates the key features, diagnosis algorithm, current management, other treatment options and extensive review of literature on this rear tumor.

[Primary neuroendocrine carcinoma of the liver. From carcinoid tumor to small-cell hepatic carcinoma: case reports and review of the literature]

Primary hepatic neuroendocrine tumors are rare neoplasms. While primary hepatic carcinoid tumors (PHCT) are well-differentiated tumors, primary hepatic small-cell carcinomas (PHSCC) represent the poorly differentiated end of the spectrum of neuroendocrine carcinomas. The first patient, suffering from PHCT, has had a follow-up for 32 years and is still alive. Within this time, the tumor relapsed 4 times with unchanged histology and immunohistochemistry features. The second patient suffered from small-cell carcinoma of the liver. There were no risk factors for a hepatocellular carcinoma. An extensive preoperative and postoperative diagnostic investigation could rule out an extrahepatic primary site. Immunohistochemically the tumor was negative for Hepar-1, AFP, TTF1 and CDX2 but reacted positively with CD56 and sporadically with the keratins 8, 18 and 20. A neuroendocrine PHSCC was diagnosed. After neoadjuvant cytostatic treatment the carcinoma was completely extirpated and 18 months after treatment the patient is healthy.PHCT and PHSCC have to be clearly separated from hepatocellular and cholangiocellular carcinomas. Exclusion of an extrahepatic primary site requires an accurate and synoptic analysis of clinical, radiologic and pathologic findings. Surgical resection is the treatment of choice.

Long-term survival after resection for primary hepatic carcinoid tumor

BACKGROUND

Primary hepatic carcinoid tumors (PHCTs) are extremely rare, and fewer than 50 cases have been reported in the English-language literature. We report a patient with a PHCT and review the cases in the literature.

METHODS

Our patient presented with symptoms and underwent liver resection for PHCT and regional lymph node metastasis. He underwent two more liver resections over the following 7 years for recurrent PHCT. Cases reported in the English-language literature were reviewed and survival analysis was performed with the Kaplan-Meier method. The survival impacts of age, gender, tumor foci, extrahepatic metastasis, unilobar versus bilobar disease, and type of preoperative treatment were determined by means of log-rank test.

RESULTS

Our patient has been free of symptoms for 14 years of follow-up and free of disease for 8 years of follow-up. Forty-eight cases of PHCT were found in the literature, and 92% of these patients underwent resection. Actuarial 5- and 10-year survival for all patients was 78% and 59%, respectively, whereas for resected patients, 10-year survival was 68%. The administration of preoperative chemotherapy, radiation therapy, or chemoembolization did not impact survival, nor did age, gender, presence of extrahepatic metastasis, number of tumors, or distribution of the tumor within the liver.

CONCLUSIONS

Resection is the treatment of choice for PHCT and has provided favorable outcomes. Resection for PHCT can be performed in most patients and offers long-term survival.

Primary hepatic carcinoid tumours

BACKGROUND

Carcinoid tumours of the liver are predominantly metastases from the gastrointestinal tract. Primary hepatic carcinoids are extremely rare.

DISCUSSION

In contrast to metastases, primary hepatic carcinoids are usually solitary and resectable. It is important that these tumours are differentiated from metastases. Complete surgical resection should be contemplated and is generally curative.

Pancreatic polypeptide-related tumors

PP-producing tumors are mostly located in the pancreas and may present as three pathologic lesions: pure PP-omas, mixed tumors with minor PP cell population, and PP-cell hyperplasia. These tumors are among the most common multiple adenomas frequently found in patients with multiple endocrine neoplasia type 1. Hypersecretion and high circulating levels of PP are frequently found. They are symptomless but may be useful for the identification of the pancreatic tumors. Numerous types of extrapancreatic endocrine tumors are able to synthesize and secrete PP. They occur mostly but not exclusively in the gastrointestinal tract, particularly in the rectum. The inactivation of the MEN 1 gene at 11q13 appears to be involved in the development of pancreatic but not of rectal PP-producing tumors.

Fine needle aspiration diagnosis of neuroendocrine tumors in the liver

Ten neuroendocrine tumors (NET) in the liver are presented, in which the diagnosis was made on fine needle aspiration cytology and cell blocks from the aspirate. In seven of the patients with liver metastasis, a biopsy-proven extrahepatic primary NET had been previously diagnosed, while in three patients no extrahepatic neoplasm could be identified, suggesting that the NET may have been a primary in the liver. Based on cytomorphological findings the cases were typed as either round cell type, spindle cell type or polygonal cell type. In all cases, immunopositivity for neuroendocrine markers provided reliable evidence of the cell of origin and distinguished them from well-differentiated hepatocellular carcinoma, adenocarcinomas and other neoplasms, which sometimes may present a diagnostic dilemma.

Primary hepatic carcinoid and neuroendocrine carcinoma: clinicopathological and immunohistochemical study of five cases

Primary hepatic carcinoid and neuroendocrine carcinoma (NEC) are rare tumors. We experienced three carcinoids and two NEC originating in the liver during the past 25 years and attempted to elucidate the clinicopathological and immunohistochemical features of these tumors. The patients had no endocrine symptoms despite two of them having elevated plasma serotonin. Three of the five patients died of the tumor after operation with an average survival time of 20.6 months. All tumors were large (up to 26 cm in diameter), four of them solitary and one multinodular, and were not associated with liver cirrhosis. The carcinoid tumors showed insular, trabecular or glandular arrangement of argyrophilic cells, whereas in the NEC this histological pattern was distorted. Immunohistochemically the tumors showed expression of chromogranin A (all cases), chromogranin B (three cases), pancreastatin and chromostatin (four cases, respectively), prohormone convertase PC3 (three cases), carcinoembryonic antigen (CEA) and CA19-9 (two cases), cytokeratin 56 kDa (three cases), 160 kDa neurofilament (two cases) and neuron-specific enolase (two cases). Serotonin and glucagon were sporadically detected in two tumors. The most useful marker to confirm the diagnosis was chromogranin A, which was cleaved to pancreastatin and chromostatin in the tumor tissue, and was more reliable than other markers of neuroendocrine differentiation.

Pancreatic polypeptide hypersecretion associated with a neuroendocrine carcinoma of the gallbladder

The authors report a case of a suspected pure pancreatic polypeptide-secreting neuroendocrine carcinoma of the gallbladder. The tumor was initially interpreted as an adenocarcinoma of the gallbladder, but was found to have a neuroendocrine component after review. The pathology supports the view that a primitive epithelial stem cell can express both epithelial and neuroendocrine characteristics and can differentiate into both an adenocarcinoma and a neuroendocrine carcinoma. Upon recurrence, the tumor produced symptoms due to local growth, but eventually metastasized and led to the death of the patient within 4 years. The patient was treated with chemoembolization followed by the long-acting somatostatin analog octreotide acetate. The high serum level of pancreatic polypeptide may have contributed to cholestasis and cholelithiasis. Earlier measurement of serum hormone levels and identification of high pancreatic polypeptide levels may have suggested the presence of residual tumor and led to closer follow-up, imaging studies, and therapy.

Neuroendocrine carcinoma of the liver: an autopsy case

An autopsy case of hepatic neuroendocrine carcinoma is described. An 84-year-old man had a white solid tumor measuring 5 cm in greatest diameter and multiple small nodules in the non-cirrhotic liver. Microscopically, these lesions were characterized by solid nesting, trabecular, and insular arrangements of small- to medium-sized cells. The tumor cells were argyrophilic and electron microscopy showed dense core granules and formation of bile canaliculi. Immunohistochemically, the tumor cells were positive for cytokeratin CAM 5.2, chromogranin A, Leu-7, neuron-specific enolase, and alpha-fetoprotein. The tumor was diploid by flow cytometry. The patient had metastases in the vertebrae, lung, pancreas, and an hepatic hilar lymph node. The patient had an occult rectal tumor of intramucosal well-differentiated tubular adenocarcinoma without metastasis. No alternative primary source of the endocrine tumor was detected. The patient died 1 month after presentation.

Histocytologic diagnosis of neuroendocrine tumors in the liver: a retrospective study of 23 cases

A series of 23 needle biopsies of neuroendocrine tumors occurring in the liver is described. Aspirate smears, core biopsies, and touch preparations were examined. Eighteen of the 23 patients had been previously diagnosed: 9 patients had been correctly identified as having a neuroendocrine tumor, and 9 patients had been originally misdiagnosed. Five of the patients in this series had no previously identified neoplasia. Immunohistochemical staining confirmed the neuroendocrine nature of the tumors in each of the cases. On the basis of cytomorphology, these cases were subtyped as either round cell type, spindle cell type, or polygonal cell type. The polygonal cell type of neuroendocrine tumor, as well as rare examples of the round cell type, demonstrated features similar to well-differentiated hepatocellular carcinoma and adenocarcinomas, and may present a diagnostic dilemma. Characteristic cytologic attributes of the polygonal cell type of neuroendocrine tumor which aid in its distinction from well-differentiated hepatocellular carcinoma include eccentrically located "plasmacytoid" nuclei and cellular discohesion. Findings on core needle biopsy which further identify the neuroendocrine tumors are thick fibrous stroma or small "nests" of tumor cells. The additional use of immunohistochemical staining provides reliable evidence of the cell of origin in confusing cases. Attention to these considerations will aid in the cytologic diagnosis of neuroendocrine tumors.

Primary carcinoid tumor of the liver: report of four resected cases including one with gastrin production

Four cases of primary hepatic carcinoid were identified during a retrospective study of liver resections for primary tumor. The cases included two adult males, one adult female, and a 9-year-old boy in whom gastrin levels were documented. The estimation of gastrin levels was prompted by symptoms suggestive of acid-peptic disease. One patient died postoperatively. The other three are alive and well at 3 years, 2 years, and at 1 year, respectively, after surgery, outcomes distinctly different from hepatocellular carcinomas. Diagnostic difficulties may be experienced in histologic assessment, and this may require recourse to immunohistochemistry and electron microscopy. Long-term follow-up and careful exclusion of a possible primary elsewhere are necessary for establishing the primary nature of liver carcinoids.

An 18-year follow-up of primary hepatic carcinoid with carcinoid syndrome

Primary hepatic carcinoid is extremely rare. Although one of the 18 previously reported cases was accompanied by clinical features of carcinoid syndrome, no patient manifested these features as the presenting complaint, as was true in our case. During the 18 years this patient has been followed, she has been treated with most of the major therapeutic methods, including systemic chemotherapy, hepatic artery chemoembolus injection, extended right hepatic lobectomy, and, eventually, more systemic chemotherapy and octreotide. She continues to be nearly asymptomatic and is still working. We present the results of extensive chemical and hormonal assays, briefly summarize the primary hepatic carcinoids reported previously, and review therapy of this disease.

Liver VIPoma: report of two cases and literature review

Two cases of neuroendocrine tumor in the liver, positive for VIP, without evidence of a primary tumor outside the liver is presented. One patient had a VIPoma syndrome with diarrhea, hypokalemia, and hypercalcemia, all symptoms were reversible after treatment consisting of somatostatin analogue and arterial liver embolization followed by liver resection. The other patient showed no endocrine symptoms. To the best of our knowledge, VIPomas apparently primary in the liver have not been previously described.

Hepatic neoformations

The aim of the paper is an accurate histologic description and illustration of those liver lesions that are usually summarized under the heading of "hepatic tumors and related subjects". For in some cases it may be unclear or at least controversial, whether the individual lesion is indeed an autonomous neoplasia or a malformation, regeneration or hyperplasia, the indifferent master term of neoformation is introduced, based on the fact that all of them are characterized by a cellular multiplication. According to common definitory practice the survey distinguishes between mesenchymal (angiomatous and non angiomatous) and epithelial neoformations. Among the latter hepatocellular and cholangiocellular types are distinguished, the criterium for differentiation being a phenomenological one, which is by no means identical with a histogenetical statement. The definition of subgroups mostly adheres to current nomenclatory usage; only occasionally--in the group of endothelial tumors--a novel term is employed, in view of brevity and coordination with the overall system of neoformations.

Primary hepatic carcinoid tumor

A case of primary carcinoid tumor arising in the liver of a 69 year old woman with no endocrine symptoms is reported. Histopathologically, the tumor was diagnosed initially as a hepatocellular carcinoma in the biopsy specimen, and was shown subsequently to be a carcinoid tumor, demonstrating diffuse positive staining with Grimelius method. Mucin stained with periodic acid-Schiff (PAS), alcian-blue, and mucicarmine, and was shown partially in the glandular structures. Immunohistochemically, most of the tumor cells stained positively for chromogranin-A, epithelial membrane antigen (EMA) and neuron specific enolase (NSE). Ultrastructural examination revealed electron-dense core granules, measuring 40-120 nm in diameter in some of the tumor cells. Intensive and careful searches pre- and post-operatively revealed no other primary source of tumor other than the liver. The patient was reported well with no symptoms 3 1/2 years after the operation. This case is considered to be a primary hepatic carcinoid tumor. The recent literature is reviewed, and the possible histogenesis of hepatic carcinoid tumor is discussed.

Primary hepatic neuroendocrine carcinoma in a child. Morphologic, immunocytochemical, and molecular biologic studies

BACKGROUND

Primary neuroendocrine tumor of the liver is uncommon, and virtually all reported patients with the tumor have been adults. Most of the tumors were carcinoids. The authors report an 8-year-old girl with primary hepatic neuroendocrine carcinoma.

METHODS

Histologic, ultrastructural, and immunocytochemical studies and Southern blot analysis of tumor N-myc DNA were performed in the patient.

RESULTS

Histologically, the tumor revealed a characteristic organoid pattern with a spectrum of differentiation varying from well-differentiated carcinoid-like areas to poorly differentiated pleomorphic areas. Ultrastructural features included neurosecretory granules and interdigitating cytoplasmic extensions. The tumor cells showed immunoreactivity to neuron-specific enolase (NSE), S-100 protein, chromogranin, and synaptophysin. No evidence of amplification of tumor N-myc DNA was present. However, the molecular weight of the tumor N-myc DNA (1.8 kb) was significantly lower than the normal control (from normal liver tissue) (2.0 kb).

CONCLUSIONS

This report documents the occurrence of primary hepatic neuroendocrine carcinoma in a child. Thorough studies and complete clinical evaluation are essential to the establishment of diagnosis. The result of N-myc DNA analysis probably is attributable to deletion of part of the tumor N-myc gene. The clinical implication of this finding is unknown, and additional investigation is warranted.

Ultrastructural and immunocytochemical study of a primary gastrinoma of the liver

A primary hepatic gastrinoma found in a 13-year-old boy was studied by light microscopy, immunohistochemistry, electron microscopy, and immunoelectron microscopy. Results were consistent with a neuroendocrine neoplasm with abundant gastrin-immunoreactive cells. Unlike all previously reported cases of primary hepatic neuroendocrine tumors, which have been endocrinologically asymptomatic, the patient had a Zollinger-Ellison syndrome apparently cured by surgical resection of the tumor.

Hepatoblastomas: an ultrastructural and immunohistochemical study

Seven hepatoblastomas were studied by electron microscopy, and four of these were studied by immunohistochemistry. Five tumors were purely epithelial, and two were mixed epithelial-mesenchymal. They showed a spectrum of cellular differentiation ranging from primitive epithelial cells to differentiated cells resembling adult hepatocytes. Glycogen, lipid, basal lamina, and canaliculi were present in all cases. Mitochondria with large, membrane-bound, amorphous inclusions were present in one tumor, and large, complex, basal cell processes were present in two tumors. Ultrastructural features most characteristic of hepatocytes were most common in fetal type hepatoblastomas. Immunoreactive chromogranin cells were present in two tumors, one of which also contained immunoreactive somatostatin cells. The somatostatin-positive tumor had cells with granules resembling those seen in somatostatin-containing cells of normal pancreas and somatostatin-containing neuroendocrine carcinomas. Other immunoreactive substances were present, including alpha 1-antitrypsin (four cases), vimentin (embryonal cells in four cases; fetal cells in three cases), low-molecular weight cytokeratin (embryonal cells in three cases; fetal cells in four cases), and high-molecular weight cytokeratin (embryonal cells in one case; fetal cells in two cases). Osteoidlike material was positive for epithelial membrane antigen, vimentin, and S-100 protein.

Appearance of a carcinoid-like pattern in rat hepatic tumors induced by 3'-methyl-4-dimethyl-aminoazobenzene

This study investigated the histological distribution of argyrophilic cells in experimental hepatic neoplasms, the number of these cells, and the proportion of neoplasms with such cells. Seventy 6-week-old male Donryu rats were given a 0.06% 3'-methyl-4-dimethyl-aminoazobenzene (3'-MeDAB) diet for 10 weeks, followed by an ordinary diet for an additional 10 weeks. Of the 70 rats, 50 were used for this investigation; 29 had hepatic tumors, 18 had cholangiofibrosis, and the other three had oval cell proliferation only. Hepatic tissues were stained with Grimelius and Fontana-Masson stains as well as routine hematoxylin-eosin stain. Argyrophilic cells were found in the hepatic neoplasms of 8 rats without argentaffin cells, while cholangiofibrosis was associated with argentaffin cells in almost all cases. Of the 8 rats with argyrophilic cells, three had an abundant population of these cells. The argyrophilic cells were found in areas of the neoplasms with a glandular, trabecular, tubular, or poorly differentiated pattern. Electron microscopy revealed that the neoplastic cells with a positive argyrophil reaction contained small round electron-dense endocrine granules. In addition, in the areas of cholangiofibrosis, two different types of gut endocrine cells were present (G and EC cells). These results suggest that 3'-MeDAB might induce hepatic carcinoid under certain conditions, though we have yet to confirm the development of a pure hepatic carcinoid due to this substance.

'Neuroendocrine' differentiation in primary neoplasms of the liver

Thirty primary liver neoplasms (16 hepatocellular, nine biliary, and five epithelioid haemangioendotheliomas) were studied for the expression of the general 'neuroendocrine' markers, neurone specific enolase (NSE) and protein gene product 9.5 (PGP 9.5). Grimelius silver staining for neurosecretory granules and immunostaining for S100 protein, HMB-45, vasoactive intestinal polypeptide (VIP), and calcitonin were also performed. Eleven of the 16 hepatocellular carcinomas stained positively for PGP 9.5, four for NSE, six for HMB-45, and two for S100 protein. Seven exhibited granular staining by the Grimelius method; eight showed immunostaining for VIP, and two for calcitonin. Three of the five haemangioendotheliomas demonstrated positive immunostaining for PGP 9.5, and two for NSE; of the nine biliary carcinomas, two showed staining for PGP 9.5 and NSE, and four contained cells staining with the Grimelius technique. Primary neoplasms of liver may show 'neuroendocrine' differentiation and this aspect of their phenotypic expression has to be considered before predicting the site of origin of a tumour in the liver.

A clinicopathologic study of primary hepatic carcinoid tumors

Six cases of primary hepatic carcinoid tumors were studied with combined immunocytochemical and electron microscopic techniques. Positive tumor immunostaining with PHE5, LK2H10, neuron-specific enolase (NSE), serotonin, gastrin, and insulin antibodies was observed. At the ultrastructural level, cytoplasmic dense granules were seen in all the cases tested. This finding supports a putative origin of these carcinoids found in the liver from a pluripotential stem cell. The clinical course and follow-up of these cases suggests that this unusual hepatic neoplasm has a more favorable prognosis than other forms of hepatic cancer.

Role of neuropeptides and serotonin in the diagnosis of carcinoid tumors

The plasma concentrations of neuropeptides (neurotensin, substance P, motilin, somatostatin, vasoactive intestinal peptide and gastrin-releasing peptide), the urinary excretion of 5-hydroxyindoleacetic acid and serotonin, and the platelet concentration of serotonin were compared in 133 patients who could be assigned to one of four groups. These groups were as follows: carcinoid tumors present; history of carcinoid tumors; miscellaneous tumors present; and non-tumor diseases. The test with the most sensitivity (i.e., patients with carcinoid tumors labeled positive) and the test with the most specificity (i.e., patients without carcinoid tumors labeled negative) for the presence of carcinoid tumors was determined. Urinary 5-hydroxyindoleacetic acid excretion had a sensitivity of 73 percent and a specificity of 100 percent; the plasma concentration of substance P had a sensitivity of 32 percent and a specificity of 85 percent; and the plasma concentration of neurotensin had a sensitivity of 41 percent and a specificity of 60 percent. Even when basal plasma concentrations of substance P and neurotensin were elevated, there was no additional increase of these neuropeptides prior to ethanol-induced facial flushing. Although measurements of plasma neuropeptide levels may be helpful in occasional patients with carcinoid tumors, it is concluded that measurements of serotonin overproduction--such as 5-hydroxyindoleacetic acid excretion--are of more general value.

Primary neuroendocrine carcinoma of the liver

A case of primary neuroendocrine carcinoma in an unusual location, the liver, is reported. The neoplasm was composed of small, uniform cells that had distinct borders and grew in strands, ribbons and nests; its appearance resembled that of a carcinoid. Electron microscopy and special staining of the neoplastic cells confirmed the neuroendocrine nature of the tumor, and the cells showed immunoreactivity for gastrin and pancreatic polypeptide by the PAP. The recent literature is reviewed, and the possible histogenesis of hepatic neuroendocrine carcinoma is discussed.

Fibrolamellar carcinoma of liver: a primary malignant oncocytic carcinoid?

Immunohistochemical and ultrastructural findings in two cases of fibrolamellar carcinoma of the liver and two cases of hepatocellular carcinoma of the common histologic type are described. Ultrastructural examination of both cases of fibrolamellar carcinoma revealed the presence of neurosecretory (NS) granules which were sparse in some cells and abundant in others. Many of the tumor cells had a distinct oncocytic appearance with abundant mitochondria. A portion of the glutaraldehyde-fixed neoplasm was processed for the uranaffin reaction (an ultrastructural cytochemical stain specific for the NS granules of neuroendocrine tissue). Abundant uranaffin-positive granules were found in the neoplastic cells of both cases of fibrolamellar carcinoma, whereas no uranaffin-positive granules were found in hepatocellular carcinoma of the common histologic type. There was no statistical difference in the mean diameter of the uranaffin-positive granules measured from both cases. Immunohistochemistry revealed the presence of neuron-specific enolase (NSE) and serotonin in one of the two cases of fibrolamellar carcinoma and no NSE staining in two cases of hepatocellular carcinoma of the common histologic type. These findings suggest that some liver tumors presenting histologically as fibrolamellar carcinoma may be neuroendocrine in nature.

Endocrine liver tumour differential diagnosis from hepatocellular carcinoma

A liver tumour, initially diagnosed by light microscopy as a hepatocellular carcinoma, was later shown to be endocrine by argyrophilia and electron microscopy. It was tested by immunohistochemistry for insulin, glucagon, gastrin, VIP, pancreatic polypeptide, glicentin, C-peptide and somatostatin. A few cells were shown to contain somatostatin, but the secretion product in most of the cells was not identified. The patient is well, without any sign of endocrine disturbances, 18 months after the operation.

A pancreatic-polypeptide-producing tumor of the stomach

A gastric tumor was found in a 64-year-old woman who later developed flushing, tachycardia, headache, and lacrymation. The plasma pancreatic polypeptide (PP) level was 700 times normal values, and the majority of the tumor cells were immunoreactive to PP antiserum. Symptoms were alleviated, and PP levels fell after embolization of the hepatic artery for liver metastases. This is the first reported case of gastric PP-producing endocrine tumor.

Hepatocellular carcinoma with carcinoid features

A primary hepatic neoplasm with histologic features suggestive of both hepatocellular carcinoma and carcinoid tumor was studied by light microscopy, electron microscopy, and immunocytochemistry. These methods revealed areas of hepatocellular carcinoma, areas of carcinoid tumor, and mixed areas within the same cell. This case provides one more example of the coexistence of carcinoma and carcinoid in the same neoplasm and thereby supports the hypothesis that a malignantly transformed stem cell can differentiate in both epithelial and amine precursor uptake and decarboxylation (APUD) directions.

Pancreatic polypeptide-producing tumors. Report on two cases

Histochemical, chemical and clinical features of two malignant endocrine pancreatic tumors were studied. Both tumors contained pancreatic polypeptide (PP)-immunoreactivity in the majority of tumor cells. In addition, one tumor contained a few scattered serotonin-fluorescent cells and the other scattered gastrin-immunoreactive cells. Pancreatic polypeptide hypersecretion was established from both tumors. Serotonin was produced by one tumor and gastrin was secreted by the other. No PP-associated endocrine symptoms were present, whereas the hypergastrinemia may have caused a bleeding duodenal ulcer in one patient. Although both tumors were highly malignant the clinical courses in the two patients were very different; one patient died within a few months whereas the other is alive 2 years after the diagnosis.

Tumors of the diffuse endocrine system, histochemical and electron-optic aids, and pitfalls in diagnosis

Tumors of the Diffuse Endocrine System are a heterogeneous group of malignant neoplasms which have rather characteristic light microscopic and cytologic features. These are, however, not diagnostic and their identification with separation from non-neuroendocrine carcinomas require important adjunctive evaluations including histochemical analysis, immunocytochemical characterization and electron-optic identification of endocrine secretory products and paracrine effects in the cytoplasm of the neoplastic cells. The importance of proper classification cannot be over-emphasized because of the often considerable biologic and prognostic differences between neuroendocrine carcinomas and other types of carcinoma, notably metastatic carcinomas from the breast and the prostate. Furthermore, the separation of these lesions into two groups; a small cell type and those with large cells (carcinoid type) appears to have clinical significance in both diagnosis and response to therapy.

Occult hepatic sinusoid tumor of infancy simulating neuroblastoma

Two infants with hepatosplenomegaly and an occult tumor of hepatic sinusoids are reported. Although secretion of biogenic amines of neuroblastoma was not elevated, infrequent neurosecretory granules were observed by electron microscopy in the cytoplasmic processes of the tumor cells. The infants responded to vincristine and prednisone therapy and are tumor free 8 and 2 years later, respectively. The clinical, radiographic, biochemical, and microscopic findings of these cases are presented. The distinction from other infantile hepatic sinusoid small round cell tumors is based on the light and electron microscopic findings. This neuroepithelial tumor is either an unusual form of neuroblastoma or a neoplasm of APUD cell origin. If chemotherapy is utilized, it should be selective and limited.

Hyaline inclusions in a synovial sarcoma following intra-arterial chemotherapy

Hyaline inclusions were noted in cells of a typical synovial sarcoma following intra-arterial chemotherapy. Ultrastructural study revealed that the inclusions were cytoplasmic aggregates of intermediate filaments. Since the inclusions were not present in the tumor prior to treatment, it is suggested that they may have formed as a result of the infusion and that their presence may be an indicator of chemotherapeutic effect.