Peripheral carcinoid tumor of the lung with focal melanin production

Neuroendocrine carcinoma of the apocrine glands of the anal sac in a dog

A perianal subcutaneous tumor involving the anal sac developed in an 8-year-old male mixed Labrador Retriever dog. Histologically, this tumor showed typical features of the solid-type carcinoma of the apocrine glands of the anal sac. However, neoplastic cells were immunoreactive for cytokeratin 8, chromogranin A, vasoactive intestinal peptide, neuron-specific enolase, and synaptophysin, and negative for S-100 protein, α-smooth muscle actin, vimentin, glucagon, insulin, somatostatin, carcinoembryonic antigen, serotonin, and parathyroid hormone-related protein. Considering the distribution of chromogranin A-positive cells within the anal sac apocrine glands, this tumor was diagnosed as neuroendocrine carcinoma originating from the apocrine glands of the anal sac.

A neuroendocrine carcinoma of undetermined origin in a dog

In this report, we describe a case of neuroendocrine carcinoma of undetermined origin in a dog. Necropsy revealed scattered small neoplastic nodules in the bilateral lungs and a small nodule in the parapancreatic lymph node. Histopathologically, both pulmonary and lymph nodal nodules showed a similar histologic pattern, with neoplastic cells being arranged in diffusely proliferating sheet-like cellular nests separated by variable amounts of fibrous septa, sometimes forming rosettes and duct-like structures. Scattered small necrotic foci and invasion to fibrous septa were typically observed. Neoplastic cells showed round to oval-shaped nuclei with prominent nucleoli and abundant eosinophilic cytoplasm that were positive for Grimelius' silver impregnation staining and immunostaining with cytokeratin, synaptophysin, vasoactive intestinal peptide and chromogranin A, indicative of the development of a neuroendocrine carcinoma. However, judging from the distribution of tumors lacking the portion suggestive of the primary site in any organ examined, as well as no further indication of differentiation potential of neoplastic cells, this tumor has so far been diagnosed as neuroendocrine carcinoma of undetermined origin.

Carcinoid-like pattern in melanoma: report of 4 cases

Cutaneous melanoma can produce a wide variety of unusual morphological appearances, sometimes mimicking other tumors. We report on 4 cases of melanoma with carcinoid-like features, namely, arrangement of neoplastic cells in trabecules, ribbons, pseudorosettes, rosettes, and/or small round islands. A total of 10 biopsies from 4 patients were available for a histopathological study comprising congenital nevus, a nodule that had developed in this nevus and its persistence/recurrence, 3 primary cutaneous lesions, 3 metastases, and a recurrent/persistent lesion. In 7 of these 10 lesions, the most characteristic finding was a distinctive arrangement of the neoplastic cells as trabecules, ribbons, pseudorosettes, rosettes, or small round insular islands, thus closely resembling cell arrangement in carcinoids of various organs. All these tumors were positive for melanocytic markers. No neuroendocrine differentiation was demonstrated immunohistochemically. We conclude that the carcinoid-like pattern in melanoma, namely, the pattern in which neoplastic cells are arranged in trabecules, ribbons, cords, rosettes, pseudorosettes, and small round insular nests resembling those in carcinoids, is a distinctive pattern, which may rarely occur in primary cutaneous melanoma, its recurrence or metastasis, or in a melanoma associated with a large congenital nevus. This morphological type of melanoma may produce a serious diagnostic pitfall, but despite a confusing microscopic appearance, these tumors seem to demonstrate a conventional immunohistochemical profile.

Neuroendocrine carcinoma in the nasal cavity of ten dogs

Neuroendocrine (NE) carcinoma was diagnosed in 10 dogs. In six cases examined by cephalometric radiography and computerized tomography, a large mass was seen to fill the nasal cavity. Histopathologically, sheets, nests or ribbons of neoplastic cells were separated by delicate or thick fibrovascular stroma. The neoplastic cells were round, oval, or spindle-shaped; cytoplasmic granules and hyperchromatic nuclei with prominent nucleoli were present. Neoplastic cells were invariably immunohistochemically positive for cytokeratin (CK) AE1/AE3, neuron-specific enolase, chromogranin A and vasoactive intestinal polypeptide. Eight dogs were positive for S100 protein, seven for synaptophysin, five for protein gene product 9.5, two for somatostatin, and one for Leu-7. Immunolabelling gave negative results for CK 8, CK 19, calcitonin, calcitonin gene-related polypeptide, neurofilaments, serotonin, gastrin and glial fibrillary acidic protein. Ultrastructurally, the neoplastic cells contained a large number of round, membrane-bounded, densely-cored granules corresponding to neurosecretory granules. These observations were consistent with the neuroendocrine nature of the carcinomas.

Immunohistochemical evaluation of a malignant intestinal carcinoid in a dog

An intestinal carcinoid with multiple metastases was identified in a 5-year-old male Shih Tzu with a clinical history of anemia, fatigue, anorexia, vomiting, intermittent diarrhea, intestinal bleeding, and progressive emaciation. There was a yellowish-white mass 15 mm in diameter in the anterior jejunum and white nodules consistent with metastases in many organs. Histopathologically, the mass consisted of neoplastic cells arranged in lobules, trabeculae, or closely interdigitating islands of cells. Neoplastic cells were generally polygonal with round hyperchromatic nuclei, modest amounts of eosinophilic cytoplasm, and eosinophilic cytoplasmic granules. Mitoses were common. Rosette formations of tumor cells were apparent in metastatic tumors. Immunohistochemically, tumor cells stained positive for cytokeratin 13, synaptophysin, protein gene product 9.5, neuron-specific enolase, chromogranin A, calcitonin gene-related peptide, serotonin (5-HT), and Leu-7. Serum 5-HT concentrations for this dog were increased 10-fold compared with those of normal dogs. All findings were consistent with a diagnosis of a malignant intestinal carcinoid.

Pigmented neuroendocrine tumor of the lung, showing neuromelanin

A pigmented neuroendocrine tumor was discovered incidentally in a 62-year-old woman through examination by chest computed tomography. The tumor was located in the left lower lobe, S6, of the lung and was 8 mm in diameter. The preoperative percutaneous needle biopsy was interpreted as a tumor suggestive of small cell carcinoma. Histological examination of the operated lobectomy material revealed that the nodule was a neuroendocrine tumor consisting of mainly spindle-shaped cells and several pigmented cells. Electron microscopy showed several dense-core neurosecretory-type granules in tumor cells, as well as abundant, pleomorphic electron-dense granules in pigmented cells much larger in size and most consistent with lipofuscin or neuromelanin. No melanosomes or premelanosomes were identified. Considering the result of ultrastructural and histochemical studies, the pigment was considered most likely neuromelanin. Neuromelanin is found in neurons of substantia nigra and locus ceruleus, and sympathetic ganglion cells. It is rarely found in neuroendocrine tumors and we review the available reports regarding pigmented carcinoid tumor.

Carcinoid tumors of the lung: immuno- and ligandohistochemistry, analysis of integrated optical density, syntactic structure analysis, clinical data, and prognosis of patients treated surgically

BACKGROUND

Analysis of potentially prognostic relevant factors of carcinoid tumors of the lung.

METHODS

Clinical features, tumor size, and features derived from immuno- and ligandohistochemistry, cytometry and histometry, and survival have been analyzed in 82 potentially curatively resected carcinoid tumors of the lung.

RESULTS

Patients with typical carcinoid tumors had a longer history of symptoms (13 vs. 8 months), fewer smoked (30% vs. 80%), and developed less frequently lymph node metastases (20% vs. 65%) compared to patients with atypical carcinoids. Statistically significant differences between both cell types have been observed in cytometric and histometric features, and binding of Lewis A trisaccharide (Lea). Prognosis is associated with the cell type, presence of lymph node metastases and heparin-binding lectin (HBL), certain cytometric and structural features, and binding of macrophage migration inhibitory factor (MIF) and beta-N-acetyl-D-galactosamine (beta-GalNAc).

CONCLUSIONS

Complete lymph node dissection is necessary, data of cytometry, histometry, and ligandohistochemistry might eventually predict the course of the disease.

Melanotic paraganglioma of the posterior mediastinum

A melanotic paraganglioma occurred in a 57-year-old woman, located in the left paravertebral space of the upper mediastinum. It was totally resected. During a 5 year follow up period neither tumour recurrence nor metastasis were observed. Histological examination of the tumour revealed a paraganglioma with monomorphous chief cell like elements which were arranged in a "zellballen" pattern. Immunohistochemical results also were in accordance with the diagnosis since neuron-specific enolase, chromogranin and synaptophysin were found in tumour cells whereas keratin was not. Additionally, neurosecretory granules were found in tumour cells during electron microscopy. A peculiar feature of the tumour was its strong pigmentation due to melanin located within the tumour cells and tumour associated melanophages. The simultaneous expression of functional properties of two different neural crest derived cells in one tumour stresses the close relationship between all neural crest elements and is in accordance with the observation of other melanotic, non-melanomatous tumours.