Carcinoid tumor of the vermiform appendix with cushing's syndrome. Ultrastructural study of a case

Malignant neoplasms of the appendix

BACKGROUND

Appendiceal neoplasms, first described in 1882, are still rare, with pre-operative diagnosis invariably difficult. We present our 10-year experience of these lesions with a review of current epidemiology, pathology and treatment modalities.

MATERIALS AND METHODS

A retrospective histopathological review of all appendicectomy specimens was completed between April 1994 and December 2003 to identify patients diagnosed with malignant neoplasms. Patient demographics, operative details, histopathology and clinical outcomes were obtained from case notes. A literature search of the PubMed database was then performed using the medical search headings; appendix, tumour, neoplasm and malignancy.

RESULTS

Twenty-two patients (eight men) were identified during the study period, with no age difference between gender (mean age in women 58, range 14-83 vs mean age in men 55, range 16-78). Eleven patients were found to have carcinoid-type tumours, eight patients with adenocarcinomas and three patients with lymphomas. Other appendiceal pathologies were identified after appendicectomies, hemicolectomy and oophorectomy. Mean follow-up was 41 months (range 1-125 months). Fourteen patients were alive at the end of follow-up. Patients with classical carcinoid tumours (CCT) had better outcomes than patients with the goblet cell carcinoid, adenocarcinoma and lymphoma.

CONCLUSIONS

From our own experience and a subsequent review of the literature, we recommend right hemicolectomy as the treatment of choice for all malignant appendiceal neoplasms, except for small CCT less than 2 cm in diameter at the tip of the appendix, with a low proliferative index, without angiolymphatic or mesoappendiceal extension. Further adjuvant therapy should be considered after oncological assessment.

Surgical treatment of malignant carcinoid tumours of the appendix

Since their first description in 1882, malignant neoplasms of the appendix still remain rare. Malignant carcinoid tumours are the most common accounting for 85% of all appendiceal neoplasms. Preoperative diagnosis is invariably difficult, and precise treatment protocols for these neoplasms remain unclear. We reviewed our experience and searched published evidence to produce management guidelines. A retrospective review of all malignant carcinoid tumours diagnosed in our hospital between April 1994 and December 2003 was performed. Patient demographics, operative details, histological types and clinical outcomes were retrieved from case notes supplemented by a questionnaire to the patient's General Practitioner. A literature search was then performed. Nine patients were identified with classical carcinoid tumours (CCT); (M = 3 and F = 6, mean age: 43, range 14-81) and two patients with goblet-cell morphology (F = 2, age 46 and 76). Mean follow-up was 63 months (range 1-125 months). Nine patients were alive at the end of follow-up. Appendicectomy was performed for acute appendicitis. Other appendiceal pathologies were identified following hemicolectomy and oophorectomy. CCT are the most common tumours and have the better prognosis. From our experience and subsequent review of the literature, we recommend right hemicolectomy as the treatment of choice for malignant carcinoid tumours. However, small CCTs less than 2 cm in diameter at the tip of the appendix, with a low proliferative index, without angiolymphatic or mesoappendiceal extension can be treated by appendicectomy. Following oncological assessment, further adjuvant therapy should be considered for patients with advanced disease.

Neoplastic lesions of the appendix

Neoplasms occur in 0.5 per cent of appendices. Ultrasonography or computed tomography is beneficial, but preoperative detection is rare. At operation, the diagnosis is considered in under half of cases. Mucocele, localized pseudomyxoma peritonei, benign tumours and most appendiceal carcinoids are cured by appendicectomy alone. Right hemicolectomy is indicated for: (1) invasive adenocarcinoma; (2) tumours close to the caecum; (3) lesions larger than 2 cm; (4) mucin production; (5) invasion of the lymphatics, serosa or mesoappendix; and (6) cellular pleomorphism with a high mitotic rate. Tumours of 1-2 cm, small mucinous carcinoids, adenocarcinoma confined to the mucosa, and tumours in children may be treated by appendicectomy alone at the surgeon's discretion. The 5-year survival rate associated with classical carcinoid is more than 90 per cent. The prognosis of mucinous carcinoid is intermediate between that of classical carcinoid and well differentiated adenocarcinoma. The prognosis of adenocarcinoma is determined by Dukes' stage and is similar, stage for stage, to that of colorectal carcinoma.

Carcinoid tumor of the appendix in the first two decades of life

Carcinoid tumor of the appendix is the most common neoplasm of the gastrointestinal tract in childhood and adolescence. Sufficient long-term follow-up data after surgical treatment are not currently available for patients diagnosed during the first two decades of life. From 1936 to 1988, 23 patients were observed at this institution with histologically confirmed carcinoid tumors involving the vermiform appendix. In contrast to the adult experience, in which the tumor is most commonly encountered as the result of an incidental appendectomy, 18 of these patients presented with signs and symptoms of an acute abdomen directing the surgeon to the appendix. In the other five cases, surgery was performed for other reasons. Median age at presentation was 13.0 years (range, 6 to 20 years). Fourteen patients were female, nine were male. Simple appendectomy was the initial procedure for all patients. Tumor size ranged from "microscopic" to 2.5 cm in largest dimension. Three patients subsequently underwent right hemicolectomy, and one patient had removal of a residual appendiceal stump, but no residual or metastatic tumor tissue was found in any of the resected specimens. Nineteen patients underwent simple appendectomy alone. Eighteen available specimens were reviewed at the time of this study for confirmation of histology and degree of invasion. The tumor invaded to the serosa in nine of 23 (39%). The mesoappendix or periappendiceal fat was involved in seven of 23 (30%). Vessel invasion was not noted in any specimen. Our median follow-up time was very long, being 26 years (range, 9 months to 51 years). No patient has had evidence of recurrent or metastatic disease.(ABSTRACT TRUNCATED AT 250 WORDS)

The neuroendocrine products of intestinal carcinoids. An immunoperoxidase study of 35 carcinoid tumors stained for serotonin and eight polypeptide hormones

The intestinal carcinoid tumors of 26 patients were stained for the presence of serotonin, gastrin, somatostatin, motilin, secretin, glucagon, pancreatic polypeptide, ACTH, and neurotensin. Argentaffin and argyrophil stains were also performed in all cases. Thirty-five separate tumors (counting metastases and multiple primaries) from the 26 patients were studied. Serotonin was present in 30 of the 35 tumors. Nineteen tumors contained serotonin only. Fourteen tumors contained multiple neuroendocrine products. One tumor contained gastrin only. One tumor did not stain immunohistochemically, but was argyrophilic. Metastatic deposits were studied in nine patients. Some metastases produced the identical neuroendocrine products as the primary tumor, whereas others produced either additional or fewer hormones than the primary tumor. Moreover, different metastases from the same primary tumor were observed to produce different hormones. Argyrophilic cells were present in all cases and were much more numerous than cells staining by immunohistochemistry. Argyrophilic cells probably contain monoamines and polypeptide hormones in addition to those studied in this series. The argyrophil stain was the best general stain in this study for the demonstration of neuroendocrine cells. Argentaffin staining was negative in ten cases that were serotonin positive and two argentaffin positive cases were serotonin negative. The carcinoid syndrome, as clinically defined by the presence of flushing and diarrhea, was noted in five patients, all of whom had serotonin-containing small bowel carcinoids. Endocrine-related symptoms were not clinically appreciated in the remaining patients.

Surgical management of the ectopic ACTH syndrome

Most patients with extra-pituitary ACTH-secreting tumors die from carcinoma, but a few can benefit from operation. Of 96 patients with Cushing's syndrome, 11 probably had such tumors. There were three modes of presentation: (1) three had malignant tumors with visceral metastases initially. One (bronchial carcinoid) died without operation. Two with carcinoma (thyroid medullary and islet-cell) underwent adrenalectomy with remission, but died soon. (2) three had apparently benign tumors initially. One (appendicular carcinoid) underwent appendectomy and one (bronchial carcinoid with hilar node metastases) underwent lobectomy. Both had rapid remissions. The third (pheochromocytoma) died after resection of the tumor. (3) five patients had no obvious tumors and underwent adrenalectomy with remission. In one a benign bronchial carcinoid was removed later. Four others remain well, but without localizing signs of tumor. The main biochemical features in all were hypokalemic alkalosis and very high urinary excretion of free cortisol. Seven of the eight patients without visceral metastases are in remission from one to 15 years after operation.

Neurosecretory granule-like structures in lymphomas

This report concerns the finding of round to ovoid electron dense, membrane bound structures 100 to 300 nm. in average diameter in four non-Hodgkin lymphoma cases studied ultrastructurally. In three of the cases the material for electron microscopy was obtained from lymph nodes. Two of the lymph nodes were replaced by nodular, poorly to moderately differentiated lymphocytic lymphoma, and the third was effaced by a diffuse histiocytic lymphoma. In the fourth case the specimen examined consisted of a spleen also replaced by nodular, poorly differentiate lymphocytic lymphoma. All cases appear to be primary abdominal lymphomas. The structures identified in the four lymphomas were similar in appearance to membrane bound neurosecretory granules when viewed by electron microscopy. It is proposed that the electron dense particles may represent peculiar lysosomes. Further cytochemical examination is needed to adequately characterize them. Although the presence of typical lysosomal granules in normal lymphocytes is a well known finding, we have not seen the type of granules described here i normal lymphocytes. Owing to the frequent use of electron microscopy examination to differentiate small cell undifferentiated (oat cell) carcinomas and, occasionally, other neuroendocrine neoplasms from lymphomas, the finding of these neurosecretory-like structures in lymphomas creates significant difficulty in the differential diagnosis and separation of these neoplasms by ultrastructural analysis.

Ultrastructure of the goblet cell type of adenocarcinoid of the appendix

Two examples of the goblet cell form of adenocarcinoid were studied with electron microscopy. Mucin was present in the form of large and small vacuoles or small patches of denser mucin granules. A small population of cells had a complement of organelles similar to the more obvious goblet cells but contained little or no identifiable product. Enterochromaffin cells were similar to those seen in normal midgut and in conventional carcinoids of midgut derivation. Enterochromaffin granules and mucin were not mixed with one another. Cell types transitional between mucinous and enterochromaffin were not found. Although study of plasmalemmae was hindered to a degree by artifacts due to tengential sectioning and, possibly, insufficiently rapid fixation, we favor the interpretation that the goblet cell type of adenocarcinoid is composed of two separate classes of cells.

Immunohistological study on the ACTH producing islet cell carcinoma of the pancreas

ACTH producing cells in islet cell carcinoma associated with Cushing's syndrome were studied by an improved immunoperoxidase as well as immunofluorescence technique. The cells which contained ACTH antigen were distributed throughout the tumor tissue of both primary and metastatic lesions in rather small numbers. In the small cancer nests they were present in an irregular or mosaic pattern and, on the contrary, they tend to line along the margin in the larger nests. The intracytoplasmic localization of the ACTH antigen was characteristically demonstrated in the infranuclear area of the tumor cells, closely simulating that of the argentaffin granules of the enterochromaffin cells. The electron microscopic observation identified membrane enclosed, cored granules, 200-300 nm in diameter, present in clusters in the infranuclear area of some tumor cells, which were considered corresponding well to the ACTH positive cells in immune staining.

Argyrophil cell carcinomas (apudomas) of the uterine cervix. Light and electron microscopic observations of 5 cases

Of a series of 97 invasive carcinomas of the cervix, 5 were found to have argyrophil tumor cells, and 3 of these 5 tumors were studied by electron microscopy. The ages of the 5 patients ranged from 36 to 49 years, with a mean age of 42.4 years. The morphologic features of these five tumors were well consistent with those described on a variety of endocrine polypeptide neoplasms such as thyroid medullary carcinomas, carcinoids, pancreatic islet-cell tumors, and oat cell carcinomas of the lung. Microscopically, the 5 tumors were characterized by the formation of solid-sheets, ribbons, streams, and rosettes. They were characterized electron microscopically by the presence of neurosecretory-type granules, the abundance of intracytoplasmic microfilaments, the absence of tonofibrils, and the paucity of desmosomal attachments. On the basis of the microscopic, electron microscopic and cytochemical characteristics, it is suggested that the tumors are a specific type of cervical carcinoma derived from the argyrophil cells, normally found among the linings of the endocervical glands and the cervical squamous epithelium. We believe these 5 tumors should be regarded as an endocrine tumor, another member of apudomas.