Ki67 does not predict recurrence for low-grade appendiceal mucinous neoplasms with peritoneal dissemination after cytoreductive surgery and HIPEC

Low-grade appendiceal mucinous neoplasms (LAMN) can disseminate to become low-grade mucinous carcinoma peritonei (LGMCP), which is optimally treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). Approximately half of the patients with LGMCP recur despite complete cytoreduction, and risk factors for recurrence are poorly understood. We sought to evaluate if Ki67 predicts progression of LGMCP after CRS/HIPEC. A retrospective review of a prospectively maintained database was performed to identify patients treated with complete CRS/HIPEC for LGMCP from 2008 to 2019 with Ki67 assessed. Patient characteristics, histologic data, average and focally high "hotspot") Ki67 index, progression-free survival (PFS), and overall survival (OS) were analyzed. Ki-67 immunostain was performed on the histologic section with the highest cellularity and architectural complexity. Forty-four patients with LGMCP (55% male, median age 61) were identified. The median Ki67 score and hotspot Ki67 score was 15% (1-70) and 50% (1-90), respectively. On univariate analysis, average Ki67 and hotspot Ki67 were not predictive of PFS when analyzed as continuous normalized values (HR 1.0, p = 0.79 and HR 1.1, p = 0.38, respectively) or as categorical values when stratified by the median (HR 0.9, p = 0.67 and HR 1.0, p = 0.93). This remained true on multivariate analysis when stratified for peritoneal cancer index, CEA, and completeness of cytoreduction score for both normalized Ki67 and hotspot Ki67 (HR 0.9 [95% CI 0.8-1.3], p = 0.94 and HR 1.04 [95% CI 0.8-1.3], p = 0.73, respectively). Ki67 failed to predict disease recurrence for patients with LGMCP in this cohort.

Loss of PTEN and Increased pAKT Expression Distinguishes Aggressive Low-grade Neuroendocrine Tumors

A major problem in neuroendocrine pathology is the identification and separation of aggressive low-grade neuroendocrine tumors (LGNETs) from those with a benign or more indolent behavior. Presently there are no known morphologic or molecular parameters which can predict how localized LGNETs will behave. The phosphatase and tensin homolog (PTEN) gene negatively regulates the PI3K-AKT-mTOR pathway and inhibits neoplastic cell survival and proliferation and has recently been identified as a neuroendocrine tumor differentiation marker. We hypothesized loss of PTEN may also identify LGNETs that demonstrate aggressive behavior. We studied PTEN and pAKT expression in 18 LGNETs using specific monoclonal antibodies. Follow up was obtained for a minimum of five years on all patients. 8/18 cases had strong PTEN expression and showed no evidence of disease on >5 years follow-up. 10 cases demonstrated loss of PTEN expression; 9/10 had positive pAKT expression, and 7/9 had recurrence and/or metastases. Lung and appendiceal LGNETs uniformly had high PTEN expression and a markedly better prognosis than their gastroenteropancreatic (GEP) counterparts. Loss of PTEN correlated significantly with the positive expression of pAKT (P=0.0027) and aggressive behavior of LGNETs (p=0.0002). Loss of PTEN and increased pAKT correlated with the metastatic potential of LGNETs (p=0.0011 and 0.0248 respectively). Loss of PTEN and increased pAKT expression distinguishes aggressive LGNETs from those with more indolent behavior.

Two independent primary mucinous tumors involving the appendix and ovary accompanied with acellular pseudomyxoma peritonei

We report a case of a 30-year-old woman who had complained of lower abdominal distension. She was noted to have a history of primary mucinous tumor of the left ovary (13.2 × 9.9 × 10.4 cm) that was removed surgically. Two years later she developed the same tumor on her left ovary (8.7 × 6.0 × 6.9 cm) and also had appendiceal mucinous tumor accompanied with acellular PMP. Final pathology revealed two truly independent primary mucinous tumors involving the appendix and ovary accompanied with acellular PMP. We recommend a minimum follow-up of 5 years for the patient to detect any development of mucinous tumors and the acellular pseudomyxoma peritonei.

Somatostatin receptor 2 and 5 expressions in gastroenteropancreatic neuroendocrine tumors in Turkey

BACKGROUND

Gastroenteropancreatic neuroendocrine tumors (GNs) are slow growing and although their incidence has increased in recent years, they are relatively rarely seen. Somatostatin analogues are used in the treatment of GNs that express somatostatin receptor (SR). We aimed to investigate the expression of SR2 and SR5 in GNs.

MATERIALS AND METHODS

In this study the expression of SR2 and SR5 was investigated immunohistochemically in 49 cases (26 males, 23 females) diagnosed and graded with GN according to the World Health Organization classification 2010.

RESULTS

The percentage of SR2 staining was 91.0% in grade 1, 82.8% in grade 2 and 100% in grade 3. On the other hand, the percentage of SR5 staining was 81.8% % in grade 1, 60.0% in grade 2 and 0% in grade 3. According to the tumor localization, the percentages of SR2 expression were as follows: pancreas 85.7%, stomach 100%, small bowel 70%, appendix 85.7% and rectum 100%. The percentages of SR5 expression were: pancreas 61,9%, stomach 37.5%, small bowel 70%, appendix 71.5% and rectum 66.6%. There was a significant negative correlation between ki67 percentage and SR5 expression (r=-0.341, p=0.016).

CONCLUSIONS

In this study, GNs were found to highly express SR2 and SR5. Although the expression of SR2 and SR5 changed according to tumor localization, the expression of SR2 was higher than the expression of SR5 in GN. There was a significant negative correlation between ki67 and SR5. Accordingly, SR5 may be a prognostic indicator of GN.

Primary appendiceal lymphoma presenting as suspected perforated acute appendicitis: clinical, sonography and CT findings with pathologic correlation

The gastrointestinal tract is the most common site for extranodal involvement by non-Hodgkin's lymphoma. However, primary appendiceal lymphomas presenting as perforated acute appendicitis are very rare: they occur in only 0.015% of all gastrointestinal lymphoma cases. The management of this condition is still controversial, and a multimodality approach (e.g., surgery, radiation therapy, and chemotherapy) is the optimal treatment. In these cases, appendiceal non-Hodgkin's lymphomas typically manifest with acute symptoms in patients with no prior lymphoma history. Additionally, we treated our patient with a right hemicolectomy and postoperative multiagent chemotherapy.

Bowel mesentery (meso-appendix) microcystic/reticular schwannoma: Case report and literature review

Microcystic/reticular schwannoma is a recently described variant of schwannoma with a predilection for the gastrointestinal tract. Due to overlapping features with other tumors, unawareness of this tumor type may lead to diagnostic and therapeutic pitfalls. We here report a case of microcystic/reticular schwannoma arising in the meso-appendix of a 43-year-old woman. The tumor was incidentally discovered by computed tomography scan for unrelated reasons. A laparoscopic operation was performed shortly after admission. Histological examination revealed a circumscribed tumor with a striking microcystic and cribriform architecture. Immunohistochemically, the tumor cells were diffusely positive for S100 protein, glial fibrillary acid protein and protein gene product 9.5, which were consistent with a peripheral nerve sheath tumor. The patient remains well with no signs of recurrence at a 10-mo follow-up. To our knowledge, this is the first case of microcystic/reticular schwannoma arising in the meso-appendix. Albeit very rare, microcystic/reticular schwannoma should be included in the differential diagnosis of appendiceal tumors.

[A case of intussusception caused by low-grade appendiceal mucinous neoplasm with high serum levels of carcinoembryonic antigen resected by laparoscopy-assisted colectomy]

The patient was a 43-year-old woman who visited our hospital with a primary complaint of intermittent abdominal pain. Upper gastrointestinal endoscopy revealed mild gastritis. The patient was treated with oral drugs, and the course was followed. Subsequently, the abdominal pain aggravated, and computed tomography (CT) was performed, in which right colic intussusception with a 4 cm cystic mass in the advanced portion was noted. Reduction by enema was attempted on the same day; however, a residual tumorous lesion was present in the ileocecal region. The patient was diagnosed with a cecal submucosal tumor with intussusception, and therefore, laparoscopic surgery was performed. Intussusception of the entire appendix in the ascending colon was noted, for which laparoscopic ileocecal resection was performed. In the excised specimen, a cystic lesion comprising the appendix filled with mucus was present. The postoperative recovery was favorable, and the patient was discharged on the seventh postoperative day. The lesion was histopathologically diagnosed as low-grade appendiceal mucinous neoplasm.

Gangliocytic paraganglioma of the appendix with features suggestive of malignancy, a rare case report and review of the literature

We report a case of appendicial paraganglioma in a 40 year old female who presented with acute appendicitis and underwent laparoscopic appendectomy. To the best of our knowledge this is the first reported case of appendicial gangliocytic paraganglioma with features suggestive of malignancy in the modern literature. Van Eeden S. et al. reported the first case of appendicial paraganglioma in a 47 year old man who also presented with acute appendicitis. The appendectomy specimen showed a distended appendix with thickened wall, and a 1.3 cm mucosal based yellow lesion. Microscopically this lesion was centered in the submucosa and consisted of three different cell types: (a) epithelioid cells with pale eosinophilic finely granular cytoplasm containing bland oval nucleus with stippled chromatin, that form solid nests lying in a trabecular pattern and in formations reminiscent of 'Zellballen' as seen in paragangliomas (b) second type cells have large vesicular nuclei with prominent nucleoli and abundant cytoplasm that are scattered singly, (c) third type cells with bland elongated nuclei form broad fascicle and envelop the epithelioid and ganglion cells. Immunohistochemical analysis showed the epithelioid cell nests immunoreactive for synaptophysin and the ganglion-like cells and spindle Schwann cells to be immunoreactive for S100 protein, whereas all three cells populations were negative for CAM5.2 and Pancytokeratin. We do believe that an accurate diagnosis of Gangliocytic paraganglioma (GP) of the appendix was rendered, detailed microscopic examination of doubled hematoxylin and eosinophil stained sections as well as the immunohistochemical phenotype of the three components have been undertaken to confirm the diagnosis of GP.

[Neuroendocrine tumors of the appendix]

An 19-year-old woman was admitted for acute appendicitis. The histological study of the appendix revealed a tubular variant of endocrine carcinoma of the appendix. Neuroendocrine tumors ("NETs") of the appendix are rare tumors which are usually detected incidentally, affecting 0.3% to 0.9% of appendectomies. Depending on their size, but also on some other factors, including histologic type, these tumors will require specific treatment; sometimes appendectomy will not be sufficient.

Does mesoappendix infiltration predict a worse prognosis in incidental neuroendocrine tumors of the appendix? A clinicopathologic and immunohistochemical study of 15 cases

We conducted a retrospective clinicopathologic and immunohistochemical study of the biologic significance of mesoappendix infiltration in 15 appendiceal neuroendocrine tumors selected from a series of 42 primary tumors. In all cases, the tumor was found incidentally and measured less than 2 cm (mean, 0.84 cm). In 13 cases, it was located in the tip of the appendix and in the midportion in 2. Histologically, none showed relationship with overlying mucosa. Necrosis was absent; mitotic figures were rare. The Ki-67 labeling index was low (1%-2%). In all cases, S-100 protein immunostaining disclosed positive elements with cytoplasmic dendritic processes closely intermingled with neuroendocrine neoplastic cells. All patients (8 males; 7 females; mean age, 38.2 years) underwent simple appendectomy. A right-sided hemicolectomy was performed subsequently in 1 case. After a mean follow-up of 52.6 months (range, 8-143 months), none had died of disease or had recurrent or metastatic disease. Our results confirm that appendiceal neuroendocrine tumors seem to have a different phenotype from those occurring in other gastrointestinal sites. Tumors less than 2 cm, even with mesoappendiceal infiltration, have an excellent prognosis, and simple appendectomy seems to be the appropriate therapeutic approach.

Synchronous serrated adenoma of the appendix and high-grade ovarian carcinoma: a case demonstrating different origin of the two neoplasms

Association of mucinous adenomas of the appendix and mucinous ovarian tumors is well known. The origin of the ovarian tumor (metastasis from the appendix vs independent primary) is still debated. Serrated adenoma is a rare neoplasm of the distal gastrointestinal tract, and its precancerous role in the colorectum was recently postulated. A 74-year-old patient was subjected to hysterectomy with routine appendectomy due to a 17-cm tumor of her right ovary. Histological examination revealed a high-grade ovarian adenocarcinoma with peritoneal involvement. The appendix, grossly unremarkable, harbored a serrated adenoma with no evidence of invasion or malignant transformation. Immunohistochemical examination revealed CD7+, CK20-phenotype of the ovarian and reverse (CK7-, CK20+) phenotype of the appendiceal tumor. Microsatellite analysis demonstrated microsatellite instability (MSI-high) within the serrated adenoma (4/5 markers with positive amplification) and no MSI (0/6 amplified markers) in the samples from the ovarian carcinoma, its metastases and the uninvolved uterine cervix. There were also differences in LOH pattern between the ovarian adenocarcinoma and the serrated adenoma. The findings suggest two independent primaries with profound differences in tumorigenetic pathways of both lesions. To the best of our knowledge this is the first report of synchronous serrated adenoma of the appendix and ovarian carcinoma.

Gastrointestinal stromal tumors in the appendix: a clinicopathologic and immunohistochemical study of four cases

Mesenchymal tumors of the appendix are very rare, and specific stromal tumors (i.e., gastrointestinal stromal tumors, GISTs) have not been reported in this location to date. Four GISTs were identified in the review of primary mesenchymal tumors of the appendix from the files of the Armed Forces Institute of Pathology from 1970 to 1998. There were also one benign schwannoma, one diffuse neurofibroma with neurofibromatosis 1, one leiomyosarcoma in a child with HIV infection, and one inflammatory fibroid polyp. The four appendiceal GISTs occurred in adult males 56-72 years of age (mean 63 years). Two tumors occurred in patients who had surgery for appendicitis-like symptoms: one was an incidental finding during surgery for a malignant gastric epithelioid GIST and one was an incidental autopsy finding. Only one of the two appendices operated for symptoms had acute inflammation, and a polypoid GIST projected outward from the proximal part of appendix. Three tumors were partially obliterating nodules, eccentrically expanding the appendiceal wall. All four were spindle cell tumors, and three of them contained extracellular collagen globules (skeinoid fibers); none had atypia or mitotic activity (<1/50 high power fields). Immunohistochemically, two tumors studied were positive for CD117 (KIT), and two were positive for CD34. The tumors were negative for alpha-smooth muscle actin and S-100 protein. Follow-up revealed death from cardiovascular disease in one case (4 years after appendectomy) and liver failure because of malignant gastric epithelioid GIST metastatic to liver in another case 15 years after the appendectomy. This report documents the rare occurrence of CD117-positive GISTs as primary appendiceal tumors.

Goblet cell carcinoids of the appendix: immunophenotype and ultrastructural study

BACKGROUND

Goblet cell carcinoids of the appendix are rare neoplasms with uncertain biological behavior.

OBJECTIVE

The aims of our study were to evaluate the immunophenotype of this neoplasm with cell cycle/cell proliferation markers and to understand their histogenesis with ultrastructural analysis using conventional carcinoids as a frame of reference.

METHODS

Clinical data and archival pathologic material of all goblet cell carcinoids of the appendix recorded by the Saskatchewan Cancer Registry between 1970 and 1998 were reviewed and evaluated by light microscopy, histochemistry, immunohistochemistry, and electron microscopy.

RESULTS

Seven cases of goblet cell carcinoids were identified among 110 cases of conventional carcinoids of the appendix. Histopathology revealed widespread infiltration of the periappendiceal fat in all cases, with extensive perineural invasion. The cells stained strongly positive for mucicarmine, periodic acid-Schiff, periodic acid-Schiff diastase, Alcian blue, cytokeratin, and carcinoembryonic antigen. Most cases were positive for synaptophysin. Increased expression of cell proliferation markers and cell cycle markers was observed. Expression of p53 was strong in one case. Electron microscopy demonstrated the presence of mucinous vacuoles of varying sizes and occasional membrane-bound neuroendocrine granules.

CONCLUSIONS

Goblet cell carcinoids of the appendix arise from a pluripotent cell with divergent neuroendocrine and mucinous differentiation. These neoplasms are widely invasive; they demonstrate a high cellular proliferation rate and dysregulation of the cell cycle with up-regulation of cyclin D1 and p21, and down-regulation of p16. Complete removal of the tumor is recommended because of the unpredictable biological behavior of this tumor, which includes delayed local recurrences and lung metastases.

Immunohistochemical analysis of the proliferative activity of neuroendocrine tumors from various organs. Are there indications for a neuroendocrine tumor-carcinoma sequence?

Small-cell neuroendocrine carcinomas (NECs) of the prostate are believed not to derive from benign orthotopic NE epithelial cells. Instead, an origin from a putative stem cell is actually the most favored concept. Whether this concept can also be applied to neuroendocrine tumors (NETs) of other organs, especially whether there are indications for well-differentiated NET-NEC sequence, is subject of the present study. A double-labeling technique for the proliferation marker MIB-1 and the NE markers chromogranin A (ChrA) and synaptophysin (SNP) was used for the immunohistochemical analysis of 45 well-differentiated NETs, 16 well-differentiated (low-grade) NECs, and 63 high-grade NECs of the esophagus, stomach, small intestine, appendix, colon, lung, prostate, and urinary bladder. The lowest proliferative activity was found in NETs (0.85% of tumor cells), and the highest activity was found in high-grade NECs (72.5%). The expression of ChrA was highest in NETs and lowest in high-grade NECs. None of the NETs and only sporadic cells in low-grade NECs showed double labeling (up to 0.05%). Up to 50% of the tumor cells in high-grade NECs were positive for MIB-1 and SNP. The percentage of double-labeled cells ranged between 0.9 and 39.6 (mean 9.7). No double-labeled cells were found in the normal epithelium adjacent to the tumors. Transitions from NET to NEC could not be observed. NETs and low-grade NECs differ in their proliferative activity from high-grade NECs, suggesting that they may arise from different precursor cell populations.

Immunocytochemical localization of prohormone convertase 1/3 and 2 in gastrointestinal carcinoids

Gastrointestinal carcinoids are derived from the diffuse intestinal endocrine system and may produce amines and many peptides, including serotonin, chromogranin A (CGA), and tachykinins. Most peptide hormones are synthesized as bigger prohormones, which are processed to smaller active hormones by prohormone convertases (PCs). A total of 35 cases of gastrointestinal carcinoids, including gastric, duodenal, small intestinal, appendiceal, and large intestinal carcinoids, were immunocytochemically stained for serotonin, CGA, and PC 1/3 and 2, in order to colocalize CGA and PCs in the carcinoids. All carcinoids were positive for CGA and PCs. Carcinoids that stained strongly for CGA were generally weakly stained for PCs and those weakly staining for CGA were more strongly stained for PCs in the majority of the small and large intestinal tumors. Gastrointestinal carcinoids were positive for CGA and PCs, and the presence of PCs may suggest that the conversion of peptide prohormones to smaller peptide hormones occurs in gastrointestinal carcinoids. PCs immunocytochemistry may be added as a new phenotypic characterization for gastrointestinal carcinoids.

Gangliocytic paraganglioma of the appendix

AIMS

A case of gangliocytic paraganglioma is reported in the appendix which, to the best of our knowledge, is the first case at this particular site to be described in modern literature.

METHODS AND RESULTS

A 47-year-old man with signs and symptoms of acute appendicitis underwent appendectomy. In the resected specimen a tumour with a diameter of 9 mm was found, which microscopically consisted of three different cell types: (a) epithelioid cells lying in a trabecular pattern and in formations reminiscent of 'Zellballen' as seen in paragangliomas (b) spindle cells and (c) ganglion-like cells. A diagnosis of 'gangliocytic paraganglioma' was made and confirmed by immunohistochemical and ultrastructural examination.

CONCLUSION

Gangliocytic paragangliomas are rare tumours of uncertain histogenesis. More than 40 years ago a tumour in the appendix with features similar to our case was described by Masson as 'neuro-carcinoïde'. Concerning its origin, Masson, as well as other authors describing gangliocytic paragangliomas decades later, referred to the endodermal-neuroecto dermal complexes found by Van Campenhout. It is felt that the current finding of a gangliocytic paraganglioma in the appendix supports the hypothesis that gangliocytic paragangliomas arise from these embryonal structures.

Mucin deposits within inguinal hernia sacs: a presenting finding of low-grade mucinous cystic tumors of the appendix. A report of two cases and a review of the literature

Two male patients, both 41 years of age, presented clinically with a typical inguinal hernia. The herniorrhaphy specimens were found on routine pathologic examination to contain abundant mucin that was focally organizing and was devoid of associated epithelial cells. Both cases were seen in consultation because of uncertainty as to the nature of the process. The possibility that the mucin might represent spread from an appendiceal mucinous cystic tumor led to the investigation of the appendix and in both cases such a tumor was discovered. The widespread involvement of the peritoneum that is characteristic of pseudomyxoma peritonei was absent in each case. These cases represent one of the many "surprise" findings that may be encountered in hernia sac specimens and one of the many problematic pathologic manifestations that may be associated with low-grade mucinous neoplasms of the appendix. Although this phenomenon is described in the literature, experience with our two cases indicates that it may still pose a significant diagnostic challenge.

The morphologic spectrum of ovarian metastases of appendiceal adenocarcinomas: a clinicopathologic and immunohistochemical analysis of tumors often misinterpreted as primary ovarian tumors or metastatic tumors from other gastrointestinal sites

Twenty cases of ovarian metastases derived from appendiceal adenocarcinomas were analyzed. The most common presentation was a pelvic mass. The appendiceal and ovarian tumors were diagnosed concurrently in 15 cases; in the remaining five, the ovarian tumors were diagnosed before the appendiceal tumor. The appendiceal adenocarcinomas demonstrated four morphologic patterns: 1) signet ring cell type, with or without glandular or goblet cell differentiation (14 cases); 2) mixed signet ring cell and intestinal type (two cases); 3) intestinal type (two cases); and 4) typical colorectal type (two cases). The ovarian tumors were bilateral in 16 cases and were histologically similar to the associated appendiceal tumor in each case. Ovarian metastases that demonstrate signet ring cell, glandular, and goblet cell differentiation mimic metastases from gastric adenocarcinoma. Those that are derived from well-differentiated mucinous appendiceal adenocarcinomas mimic primary ovarian mucinous tumors and metastases from the pancreas and biliary tract. Metastases of appendiceal adenocarcinomas of colorectal type simulate both metastatic colorectal carcinoma and primary ovarian endometrioid carcinomas. The appendiceal and ovarian tumors were immunophenotypically identical in each case. Approximately 50% of the appendiceal and ovarian tumors were positive for cytokeratin 7 (CK 7), and all were positive for cytokeratin 20 (CK 20). CK 20 positivity of the ovarian tumors is consistent with gastrointestinal origin; CK 7 positivity does not confirm ovarian origin, because appendiceal carcinomas are positive in 50% of cases. Metastatic appendiceal adenocarcinoma should be considered in the differential diagnosis of mucinous ovarian tumors with signet ring cell, goblet cell, or intestinal type differentiation, especially when these tumors are associated with extraovarian disease and are bilateral.

Mucinous tumors of the vermiform appendix and ovary, and pseudomyxoma peritonei: histogenetic implications of cytokeratin 7 expression

Cytokeratin 7 (CK-7) has been shown to be uncommonly expressed in colonic epithelial tumors, as opposed to ovarian epithelial tumors, which are always CK-7 positive. The authors investigated the expression of CK-7 in 17 appendiceal cystadenomas and carcinomas, 20 mucinous borderline tumors of the ovary, 10 cases of simultaneous mucinous tumors of the appendix and ovary, three so-called high-stage mucinous borderline tumors of the ovary, and three cases of pseudomyxoma peritonei (PP) of unknown origin. Nine appendiceal cystadenomas were CK-7 negative; two of these were associated with PP, and the peritoneal lesions were negative as well. Three cystadenomas were CK-7 positive. Three appendiceal carcinomas were CK-7 negative, and in one case the metastases were also negative. Two carcinomas were CK-7 positive. All 20 ovarian borderline tumors were CK-7 positive. Six cases of simultaneous mucinous tumors of the ovary and appendix were CK-7 negative, as were their peritoneal mucinous deposits. Four cases showed a positive reaction in both appendiceal and ovarian sites. Two of three so-called high-stage ovarian borderline tumors were CK-7 negative. All three cases of PP of unknown origin were CK-7 negative. In conclusion, appendiceal cystadenomas are often CK-7 negative, whereas ovarian mucinous borderline tumors are always CK-7 positive. The concordant staining pattern for CK-7 of simultaneous mucinous tumors involving the appendix and ovary (60% of which were CK-7 negative) supports an appendiceal origin for these tumors. Our results also support an appendiceal (or colonic) source for any CK-7-negative mucinous tumor involving the ovary or the peritoneum. Furthermore, our findings are in agreement with the assumption that mucinous borderline-like tumors in the ovary associated with PP are not ovarian in origin but are often, if not always, metastatic from an appendiceal (or other) mucinous tumor.

Malignant pleural effusions due to adeno-endocrine-cell carcinoma of the appendix: a case report

The cellular features of adeno-endocrine-cell carcinoma of appendiceal origin are presented. The pleural fluid contained metastatic predominantly atypical cells in linear cluster accompanied by numerous mesothelial cells. The cells had small round nuclei, with a slight tendency to molding; nucleoli were absent. The cytologic findings in Papanicolaou-stained smears of the pleural fluid suggested a metastatic small-cell carcinoma of the lung. Subsequently, adeno-endocrine-cell carcinoma of the appendix was demonstrated at autopsy. Reports of such occurrences are few; no study, to the best of our knowledge, has previously documented the cytologic diagnosis in pleural fluid.

Metastasis from small cell carcinoma of the lung producing acute appendicitis

A case of acute gangrenous appendicitis with perforation caused by metastatic small cell carcinoma of the lung in a 65 year old man is reported. The manifestation of appendicitis occurred more than 4 years after the diagnosis of the bronchogenic carcinoma. With longer survival of patients with disseminated tumors it is probable that new manifestations of those malignancies will be discovered. Acute appendicitis due to metastasis from a distant neoplasm should be considered in the differential diagnosis of right lower abdominal pain in the oncology patient.

Expression of cytokeratin 7 in simultaneous mucinous tumors of the ovary and appendix

Cytokeratin 7 (CK-7) is a simple epithelial keratin that may be used to investigate the site of origin of adenocarcinomas. In fact, CK-7 is present in ovarian epithelial neoplasms but is generally absent in colonic carcinomas. This pattern of CK-7 expression may aid in elucidating the genesis of mucinous tumors occurring simultaneously in the ovary and appendix, accompanied by psuedomyxoma peritonei. Five such cases were immunostained with anti-CK-7, and all showed a concordant staining pattern of the appendiceal, ovarian, and peritoneal lesions. Two cases showed a negative reaction for CK-7 and thus would appear to represent ovarian and peritoneal metastases from an appendiceal primary tumor. Three cases were CK-7 positive, and the nature of these mucinous lesions remains open to debate; they may either represent independent primary tumors or originate from the appendix. For comparison, five Stage I mucinous borderline tumors of the ovary and their normal appendices were also stained with anti-CK-7. These ovarian tumors were all CK-7 positive, whereas the appendices were negative. It is concluded that CK-7 is capable of distinguishing a group of tumors that can reliably be classified as primary appendiceal neoplasms metastatic to the ovaries and peritoneum.

Goblet cell carcinoid of the appendix

A 47-year-old man was admitted with appendicitis, and appendectomy was performed. On microscopic examination of the resected specimen, the presence of goblet cell carcinoid in the tip of appendix was revealed. This tumor showed an aggressive nature with perineural and vascular invasion around the appendiceal serosa. The tumor was composed of two main cell populations: mucin-producing (goblet cell type) and silver-positive cells (endocrine differentiation). Additionally, a few cells were also positive for serotonin and lysozyme, but negative for gastrin and ACTH. These findings suggest that goblet cell carcinoid share some functional and histologic characteristics with carcinoid tumors and adenocarcinomas, although it is a distinct entity.

Association of mucinous tumors of the ovary and appendix. A clinicopathologic study of 25 cases

Twenty-five patients with mucinous tumors of the ovary and appendix were studied. The average age of the patients was 52 years, and the ovarian and appendiceal tumors were discovered synchronously in all but two cases. The majority had either a pelvic mass or abdominal or pelvic pain. A high frequency of bilateral ovarian tumors (11/25), and right-sided predominance for the unilateral ovarian tumors (nine right, five left) were found. Four patients had ovarian mucinous carcinomas, 10 had mucinous tumors of low malignant potential, 10 had mucinous cystadenomas, and one had a mucinous cyst. Pseudomyxoma ovarii was present in 22 cases. Twenty-two of 24 appendices were grossly abnormal. There were six appendiceal mucinous adenocarcinomas, 10 mucinous tumors of uncertain malignant potential, seven mucinous cystadenomas, one hyperplastic polyp, and one mucocele. Twelve patients had ovarian and appendiceal tumors of similar malignant potential, nine had appendiceal tumors with more aggressive morphologic features than the corresponding ovarian tumor, and four had ovarian tumors with more aggressive morphologic features than the appendiceal tumor. Eighteen patients had peritoneal involvement by mucinous epithelium admixed with mucus (nine localized, nine diffuse). Immunoperoxidase reactions for four epithelial antigens in 15 cases showed complete concordance between ovarian and appendiceal lesions in only five cases and were not helpful in determining the site of origin of the peritoneal tumor. Our findings suggest an independent origin of the ovarian and appendiceal tumors in most cases and do not favor an origin in a single site. Furthermore, it is proposed that the peritoneal lesions may arise de novo as part of a multifocal neoplastic process.

Cytokeratin expression in small intestinal and appendiceal carcinoids. A basis for classification

For a study of histogenesis of intestinal carcinoids a collection of 5 classical small intestinal carcinoids, 6 appendiceal carcinoids and 9 pheochromocytomas, were evaluated. The tumors were identified by routine morphology, silver staining and chromogranin immunocytochemistry and were then examined with regard to the expression of intermediate filaments of cytokeratin type. Eight different antisera identifying individual or combinations of cytokeratins were employed. All classical small intestinal carcinoids displayed cytokeratin immunoreactivity and an almost identical cytokeratin reaction was observed in the normal enterocytes of the small intestinal mucosa. Of the individual cytokeratin types, number 18 was most heavily expressed. The appendiceal carcinoids, like the pheochromocytomas, almost totally lacked a cytokeratin staining despite a positive reaction in the mucosa of the appendix. This, in agreement with some previous studies, indicates that the small intestinal carcinoids are histogenetically related to the epithelial cells of the intestinal mucosa, while the appendiceal carcinoids have a different histogenesis and are more like pheochromocytomas. The appendiceal carcinoid may represent a distinct type of intestinal paraganglioma. This offers one explanation for the different biological behavior of appendiceal carcinoids in comparison with the other intestinal carcinoids.

Flow cytometric DNA analysis of carcinoid tumors of the ileum and appendix

Although all carcinoid tumors are considered potentially malignant, the biologic behaviors of appendiceal and ileal carcinoids are distinctly different. Appendiceal carcinoids often behave in a benign fashion, whereas ileal carcinoids pursue an aggressive course with frequent metastasis. Whether differences in DNA ploidy are related to this disparity in tumor behavior was addressed in this study. Flow cytometric DNA analyses were performed on paraffin blocks from 11 ileal and seven appendiceal carcinoid tumor cases. The mean coefficient of variation for all samples was 3.4 +/- 0.7. DNA aneuploidy was seen in two of the appendiceal cases and in six of the ileal cases. Metastases were seen in one of the appendiceal carcinoid cases, and that tumor was aneuploid. In six cases of carcinoid of the ileum, metastases were seen; of these, five tumors were aneuploid. In the ileal cases, despite the low number of cases examined, the correlation between DNA aneuploidy and metastases nearly reached statistical significance (P = .07) and showed a much stronger correlation than tumor size and metastases (P = .4). Although no statistical significance was reached in this study, the results are highly suggestive of DNA aneuploidy being an important predictor of malignant behavior in carcinoids of the ileum.

A comparative immunohistochemical study of jejunoileal and appendiceal carcinoids. Implications for histogenesis and pathogenesis

BACKGROUND

The purpose of this study was to determine the histogenesis of jejunoileal and appendiceal carcinoids and to ascertain whether this could be useful in further explaining the pathology of these neoplasms.

METHODS

Eight cases each of multiple jejunoileal carcinoids and appendiceal carcinoids together with their respective age-matched and sex-matched controls were stained with silver stains, chromogranin A, serotonin, and S-100. Histomorphometric evaluations of the endocrine cells in the mucosa adjacent to the carcinoids were carried out and compared with the respective controls using the Student's t test.

RESULTS

All the carcinoids from both groups stained for argyrophilia, argentaffinity, chromogranin A, and serotonin. Histomorphometric evaluations showed intraepithelial endocrine cell hyperplasia (IECH) in the jejunoileal carcinoid group (P = 0.007, chromogranin; P = 0.004, serotonin) but not in the appendiceal carcinoid group. On the other hand, subepithelial endocrine cell aggregates that were separate from the main tumor were seen in two cases of appendiceal carcinoids. With S-100, all appendiceal carcinoids showed intrinsic tumor positivity whereas the jejunoileal carcinoids did not.

CONCLUSIONS

The finding of IECH with multiple jejunoileal carcinoids suggests that these carcinoids arise from a field effect. The absence of IECH with appendiceal carcinoids as well as their association with subepithelial endocrine cell aggregates and their intimate relationship with Schwann cell processes suggests that appendiceal carcinoids arise from a more discrete unit, the subepithelial neuroendocrine complex.

The demonstration of a subset of carcinoid tumours of the appendix by in situ hybridization using synthetic probes to proglucagon mRNA

Previous studies using immunohistochemistry have shown variable hormone production by carcinoid tumours of the appendix. In order to confirm the existence of a specific subset of these tumours, in situ hybridization using synthetic oligonucleotide probes to detect pre-proglucagon and pre-proinsulin mRNA was performed in formalin-fixed, paraffin-embedded material from eight tubular carcinoids, 12 insulin carcinoids, and two mucinous carcinoids. The results were correlated with standard silver and mucin stains. All tubular carcinoids but none of the insular or mucinous carcinoids contained proglucagon mRNA. Proinsulin mRNA was not detected in any of the tumours. Tubular carcinoids of the appendix constitute a definable subset of appendiceal carcinoids which have a similar distribution and prognosis to typical insular carcinoids and can be diagnosed on haematoxylin and eosin-stained sections confirmed by routine special stains. The main need for recognition is to avoid confusion with mucinous carcinoids, which have a worse prognosis and may require more aggressive treatment.

The histogenesis of appendiceal carcinoid tumours

Twenty-two appendiceal carcinoid tumours, comprising 10 classical carcinoids, six tubular carcinoids and six goblet cell carcinoids were examined by histochemistry and immunohistochemistry. All of the tumours showed evidence of neuroendocrine differentiation. Classical carcinoids were invariably intimately associated with S-100 protein positive cells, supporting an origin from sub-epithelial neuroendocrine cells. Both tubular and goblet cell carcinoids expressed cytoplasmic mucin and immunoglobulin A, and neither were associated with S-100 protein positive cells. These observations suggest that tubular and goblet cell carcinoids are derived from epithelial crypt stem cells.

Goblet cell carcinoid of the vermiform appendix with ovarian metastasis mimicking mucinous cystadenocarcinoma

We describe a case of goblet cell carcinoid of the vermiform appendix, which metastasized to the bilateral ovaries, uterus, vagina and peritoneum three years and four months after appendectomy. The appendiceal tumor showed transmural infiltration of carcinoembryonic antigen-positive goblet cell-type tumor cells, intermingled with a small number of argyrophilic cells immunoreactive for serotonin and chromogranin A. The presence of neurosecretory-type granules was confirmed ultrastructurally in some mucin-negative tumor cells. The pattern of proliferation was typical of carcinoid tumor originating from the lower-most part of the mucosa, and showed lymphatic permeation. The metastatic lesions in the pelvic organs showed either diffuse infiltration of goblet cell-type tumor cells or mucinous cystadenocarcinoma-like features, the latter being evident in the right ovary. No neuroendocrine component was identified in the metastatic deposits. The kinship of appendiceal goblet cell carcinoid to adenocarcinoma is discussed.