Endocrine GEP-cells in primary testicular teratoma

The use of immunohistochemistry in the differential diagnosis of tumors of the testis and paratestis

Although most testicular and paratesticular tumors can be recognized by their light microscopic features, some raise significant differential diagnostic questions. Immunohistochemical staining has proved of significant value in this situation. There is still a role for the traditional markers, including placental-like alkaline phosphatase and alpha-fetoprotein, but newer markers provide additional support and often have greater sensitivity and specificity for many diagnoses. OCT4 is virtually 100% sensitive and specific for seminoma, embryonal carcinoma, and intratubular germ cell neoplasia, unclassified type. Inhibin-alpha, among testicular tumors, is limited to those in the sex cord-stromal category or those having adrenocortical-type differentiation (testicular tumor of the adrenogenital syndrome) or of trophoblastic lineage. Calretinin is another positive marker for the sex cord-stromal tumors but has less specificity. Additional markers, including differential cytokeratins, c-kit, CD30, epithelial membrane antigen, S-100, melan-A, and others, are useful in specific situations. This article reviews the application of immunohistochemical markers for a number of differential diagnostic considerations in the testis and paratestis categorized according to their light microscopic patterns.

Gastrointestinal carcinoid tumours. Histogenetic, histochemical, immunohistochemical, clinical and therapeutic aspects

The increased knowledge of the pathobiology of gastrointestinal carcinoid (neuroendocrine) tumours and the improved therapeutic possibilities have brought a demand for more precise diagnosis. Although the carcinoid tumours can often be tentatively recognized in routinely processed microscopic slides, their more accurate identification requires additional diagnostic procedures. General neuroendocrine markers such as the argyrophil reaction of Grimelius and immunohistochemistry with application of antibodies against chromogranin A and of neuron-specific enolase are discriminatory staining methods which are used to reveal the neuroendocrine origin of almost all highly differentiated carcinoid tumours of the gastrointestinal tract. Mid-gut carcinoids, which predominate among these tumours almost unexceptionally contain serotonin. This biogenic amine can be demonstrated by the argentaffin reaction of Masson, serotonin immunoreactively or by formalin-induced fluorescence. The characteristic staining pattern of mid-gut carcinoids is almost invariably preserved in the metastatic deposits and consequently the staining methods for identifying serotonin can also be used on metastases to reveal a primary mid-gut carcinoid. The enterochromaffin-like (ECL) cell carcinoids of the body and fundic area of the stomach often seen in association with pernicious anaemia are argyrophil with the Sevier-Munger silver stain. Other neuroendocrine tumours, viz. antral, duodenal and rectal carcinoids should be studied by a battery of relevant peptide hormone antisera for adequate diagnosis. During the last decade new peptide hormones have been found in circulation in patients with carcinoid tumours, but serotonin and urinary 5-HIAA are still the most important markers for carcinoids of the mid-gut origin. Other clinically useful tumour markers are chromogranin A + B, pancreatic polypeptide, human chorionic gonadotropin alpha and beta subunits. For localizing procedures, angiography is the most reliable investigative method for primary tumours in the gut, whereas CT-scan and ultrasound investigations are good for detection of liver metastases. During the last five years, the therapy for malignant carcinoid tumours has been considerably improved. Chemotherapy has only revealed objective response rates in about 10-30% of the patients giving median survivals from start of therapy of about 10 months. Recently treatment with alpha interferons and the new somatostatin analogue octreotide have given objective responses in 50-75% of patients with malignant mid-gut carcinoid tumours. These patients have now a median survival from start of therapy of 70 months when treated with alpha interferons. In the future new therapies will come into use such as monoclonal antibodies and perhaps also agents blocking different growth factors.

Diagnostic pathology of gastrointestinal and pancreatic neuroendocrine tumours

The increased knowledge of the pathobiology of gastrointestinal and pancreatic neuroendocrine tumours and the improved therapeutic possibilities have brought a demand for more precise diagnosis. Although the neuroendocrine tumours can often be tentatively recognized in routinely processed microscopic slides, their more accurate identification requires additional diagnostic procedures. General neuroendocrine markers, such as the argyrophil reaction of Grimelius and immunohistochemistry with application of antibodies against chromogranin A and of neuron-specific enolase are discriminatory staining methods which are used to reveal the neuroendocrine origin of almost all highly differentiated neuroendocrine tumours of the gastrointestinal tract (carcinoids) and pancreas (insulomas). Midgut carcinoids, which predominate among these tumours almost unexceptionally contain serotonin. This biogenic amine can be demonstrated by the argentaffin reaction of Masson, serotonin immunoreactivity or by formalin-induced fluorescence. The characteristic staining pattern of midgut carcinoids is almost invariably preserved in the metastases and can thus be used to reveal a primary midgut carcinoid. The enterochromaffin-like (ECL) cell carcinoids of the body and fundic area of the stomach are argyrophil with Sevier-Munger silver stain. Other neuroendocrine tumours, viz, antral, duodenal and rectal carcinoids and insulomas, should be studied by a battery of relevant peptide hormone antisera for adequate diagnosis. About 50% of all insulin-producing insulomas are endowed with stromal amyloid deposits, which chemically are composed of a peptide designated islet amyloid polypeptide. This molecule has been observed by electron microscopical immunocytochemistry to occur exclusively in the beta-cells and is co-stored with insulin in the beta-cell granules.

Immunocytochemical and ultrastructural findings in a mature retroperitoneal teratoma

Report is made of a mature retroperitoneal teratoma in a 32-year-old man. Investigation of the tumor revealed cells immunoreactive for ACTH, Met-enkephalin, beta-LPH, serotonin, FSH, BPP, S100, Neuron-specific-enolase. These cells were mainly present in the glandular epithelium, lining the cysts of the tumor. Ultrastructurally, neuro-secretory granules were demonstrated in the cytoplasm of the tumoral endocrine cells. At no time did the patient display endocrine symptoms.

Ectopic G-29 and G-37 glucagon secretion by hypercalcemic infantile renal tumors

Four hypercalcemic infantile renal tumors were shown to secrete glucagon-like peptides. These unusual tumors were histologically classified as rhabdoid tumors of the kidney (3 cases) and a cellular mesoblastic nephroma (1 case). Elevated G-29 and G-37 glucagon levels were detected in the plasma and tumor extracts as well as in the supernatants of cultured tumor explants. Three of these tumors were heterotransplanted into the nude mice and serially passaged from a mouse to another. The glucagon level decreased in the transplanted tumor extracts with the number of passage.

Primary neuroectodermal tumour of the testis

A 51-year-old male presented with metastasis of a small cell carcinoma of unknown origin in a right inguinal lymph node. Clinical and laboratory studies failed to locate the primary tumour. After three years, a swelling appeared in the right testis, which was removed. Histological examination revealed a proliferation of small tumour cells forming irregular masses or nests that occupied most of the testicular parenchyma. At the periphery of the testicular parenchyma a few seminiferous tubules could be observed, showing a low and incomplete seminiferous epithelium and numerous tumour cells in the lumen. Most of the tumour cells showed a euchromatic nucleus with small nucleoli and scanty cytoplasm. Among these cells, larger binucleate or trinucleate cells as well as small cells with pyknotic nuclei were also observed. Mitoses were numerous. Electron microscopy revealed some tumour cells with 80 to 100 nm vesicles containing electron-dense granules. Some cells displayed dendrite-like prolongations with numerous intermediate filaments and electron-dense vesicles. This tumour is compatible with a primary neuroectodermal tumour of the testis.

Immunohistochemical localization of HCG and its subunits in testicular germ cell tumours

Native hCG and its alpha and beta subunits have been localized by immunocytochemistry in 45 testicular germ cell tumours of the testis. Positivity was found for the three molecules in areas with trophoblastic differentiation or in syncytial-like giant cells present in some seminomas. Isolated positivity of hCG alpha was demonstrated in isolated cells usually found in areas of entodermal differentiation of immature malignant teratomas, and probably of neuro-endocrine function. This finding points to genomic derepression in tumour cells and probably also indicates a variability in subunit synthesis and a defect in subunit recombination.

Post-chemotherapy surgery in advanced non-seminomatous germ-cell testicular tumours: the significance of histology with particular reference to differentiated (mature) teratoma

Of a total of 307 patients treated with chemotherapy for advanced non-seminomatous germ-cell testicular tumours between 1976 and 1983, 73 (23.8%) had masses excised after treatment. Resected tissue showed residual malignancy in 16 (22%), fibrosis and necrosis in 25 (34%) and differentiated (mature teratoma) in 32 (44%). Of the 16 patients with tumour only 7 (44%) are alive and disease-free compared with 21/25 (84%) and 27/32 (84%) for fibrosis/necrosis and differentiated teratoma respectively. In addition to histological evidence of residual tumour, elevated serum markers at the time of surgery and/or incomplete excision of residual masses were adverse prognostic features. Of 12 patients with differentiated teratoma or fibrosis who had incomplete resections or densely adherent masses excised with difficulty, 7 subsequently relapsed. The majority of differentiated teratoma patients (75%) had evidence of differentiation in their primary tumours; 88% showed cystic change in metastases and almost one-third showed an increase in the size of metastases during chemotherapy. The data suggest that post-chemotherapy surgery may have a therapeutic as well as a diagnostic role and that complete excision of residual disease should be attempted even if resection at one site has shown either fibrosis or differentiated teratoma. The significance of these findings in relation to treatment induced differentiation is discussed.

Neuroendocrine carcinoma of skin with simultaneous cytokeratin expression

An unusual tumor of the skin was removed from the thigh of a 52-year-old white male. By light microscopy, the tumor was composed of intermediate and small cells in sheets and clusters. Ultrastructural study of the tumor cells showed numerous dense core granules and dendritic cell processes as well as intermediate filaments and cell junctions frequently within the same cells. Most of the tumor cells were stained intensely by antibodies to neurone-specific enolase (NSE), a marker of cells of the central and peripheral nervous system. The neuropeptides met-enkephalin and vasoactive intestinal peptide (VIP) were also found in tumor cells. Immunohistochemistry furthermore demonstrated cytokeratin. Both the ultrastructural appearance and keratin content of this tumor set it apart from conventional Merkel cell (or trabecular) carcinoma of the skin in a manner analogous to bipartite (i.e., epidermoid and small cell) carcinoma of lung. The production of neuropeptides simultaneously with the production of keratin establishes this as a bipartite skin tumor (i.e., ectodermal and neuroectodermal phenotype). We suggest that at least some primary neuroendocrine tumors of the skin arise from multipotential ectodermal cells not of neural crest origin, as has been proposed for small cell carcinoma of lung.

Exocrine and endocrine cell differentiation in small intestinal adenocarcinomas

Sixteen adenocarcinomas of the small intestine were examined with respect to the ability of the the tumour cells to differentiate in exocrine and endocrine directions. Both intra- and extracellular mucous material was found in 14 tumors and lysozyme immunoreactivity, a characteristic of normal Paneth cells, was seen in scattered tumor cells in two cases. Three tumors contained a few argyrophil cells, indicating the presence of tumor cell population with endocrine production. In two of these tumors some tumor cells displaying an argentaffin reaction, a staining property characteristic of enterochromaffin cells storing serotonin, were also found. In one tumor examined electron microscopically, tumor cells with cytoplasmic zymogen granules were seen and also two different types of endocrine tumor cells containing neurosecretory hormone granules. The results show that the tumor cells of small-intestinal adenocarcinomas possess the ability to differentiate in both the exocrine and the endocrine direction.

Neuroendocrine cells in cystic mucinous tumours of the ovary

This histogenesis of cystic mucinous ovarian tumours is still controversial. It has been proposed that these neoplasms may arise from metaplastic ovarian surface epithelium. Others have suggested that these tumours represent monophyletic (intestinal) types of teratoma. Against this background we have studied the presence of different types of neuroendocrine cells in a series of cystic mucinous ovarian tumours. Argyrophil neuroendocrine cells were found almost exclusively in tumours which were histologically classified as borderline or low-grade mucinous carcinomas, whereas these cells were very rare in mucinous cystadenomas and in grade III and IV carcinomas. Several gut peptide hormones could be demonstrated in these cells, but only in borderline tumours and low-grade mucinous carcinomas. Mucin histochemistry did not reveal characteristic patterns in these neoplasms. The results confirm that with regard to the presence of endocrine cells the epithelium of borderline mucinous cystadenomas and mucinous cystadenocarcinomas bears strong resemblance to intestinal epithelium. These findings do not rule out the possibility that these tumours arise by metaplasia from ovarian germinal epithelium but are equally compatible with a teratomatous origin. The epithelium of most benign mucinous cystadenomas resembles that of ovarian inclusion cysts.

Duodenal somatostatinoma. Immunohistopathology and review of literature

A case of duodenal somatostatinoma is reported. The patient, a 54-year-old male, had complained of an epigastric pain due to gastric ulcer and a duodenal polyp was unexpectedly found at a gastrectomy. The polyp showed basically tubular adenocarcinoma, with negative argyrophil and argentaffin reactions. By an indirect immunofluorescent examination almost all of the tumor cells were revealed as somatostatin-immunoreactive. Big somatostatin was also positive. Radioimmunoassay of the tumor indicated 6400 pg of somatostatin-like immunoreactivity per milligram of wet tissue. This seems to be the second case of duodenal somatostatinoma, following the case reported by us previously.

Argyrophilic cell hyperplasia and an atypical carcinoid tumor in chronic ulcerative colitis

An unusual case of chronic ulcerative colitis, is presented in which an atypical carcinoid tumor was seen. Many areas of the mucosa showed glandular changes of chronic injury and dysplasia, and in these areas, argyrophilic cell hyperplasia was identified. Data is presented describing the evolution of argyrophilic cell hyperplasia as a reaction to injury, the evolution of carcinoid tumors in argyrophilic cell hyperplasia, and the relationship of the proliferating argyrophilic cells to the proliferating glandular cells in ulcerative colitis.