Cecal adenocarcinoma with prominent rhabdoid feature: report of a case with immunohistochemical, ultrastructural, and molecular analyses.

Colorectal adenocarcinoma with rhabdoid phenotype is extremely rare, and only 1 case of adenocarcinoma showing rhabdoid dedifferentiation has been reported. The authors present another case of cecal adenocarcinoma with prominent rhabdoid feature in a 66-year-old man. The 13-cm sized tumor consisted mainly of rhabdoid cells and partly of adenocarcinoma, and transition from adenocarcinoma to rhabdoid areas was noted. Ultrastructural analysis revealed intracytoplasmic aggregates of intermediate filaments in the rhabdoid cells. Adenocarcinoma cells were diffusely immunoreactive to cytokeratin 7 and AE1/3, but occasionally positive for vimentin. The rhabdoid cells were negative for cytokeratin 7, weakly/focally immunoreactive to AE1/3, and diffusely positive for vimentin. These results suggested that the rhabdoid cells were dedifferentiated adenocarcinoma. Analysis of the rhabdoid cells with molecular techniques is also presented.

Rat ileocecal immunocytoma. An ultrastructural study with special attention to the presence of viral particles.

Fifteen spontaneous immunocytomas originating in the ileocecal lymph nodes of Lou/C/Wsl rats were studied by means of electron microscopy. The histology was characteristic, the tumor being formed by an accumulation of large, rounded cells with slightly eccentric ovoid nuclei, large nucleoli, and finely condensed chromatin along the nuclear walls; the cytoplasma was rich in polyribosomes. The appearance of the rough endoplasmic reticulum was apparently the same whether or not the tumor was secretory. Its development varied from one cell to another, and in only a small proportion of cells did it attain any considerable volume. In all the tumors examined, we noted the presence of intracisternal A-particles. In its morphology, the rat immunocytoma resembled the plasmacytomas induced in mice, and it also resembled certain human tumors such as Burkitt's lymphoma.

Colonic angiomyolipoma with a monotypic expression and a predominant epithelioid component.

Angiomyolipomas are rare lesions, often arising in the kidney, and are part of a group of tumours with a diverse appearance and evidence of dual melanocytic and smooth muscle differentiation known as PEComas (tumours of perivascular epithelioid cell origin). This report describes an unusual case of a colonic PEComa in a 40 year old woman. Unlike most of the previous colonic angiomyolipomas/PEComas reported in the literature, this case formed a large, mainly extrinsic mass and was monotypic, and composed entirely of the myomatous component with no adipose tissue or typical vasculature.

Malignant carcinoid tumor complicating chronic ulcerative colitis.

A case of malignant carcinoid tumor (neuroendocrine carcinoma) of the cecum is described. The neoplasm arose in a patient who had chronic ulcerative colitis for 16 years. There is no previous documentation of this combination, which is surprising, in view of the known association of colonic adenocarcinomas and lymphomas with ulcerative colitis. The reasons for this discrepancy are discussed and it is postulated that ultrastructural examination of poorly differentiated colonic neoplasms may result in a more frequent identification of this association.

[Establishment of a cell line (HCe-8693) from human undifferentiated adenocarcinoma of the cecum and its characterization].

A human cecum undifferentiated adenocarcinoma cell line (HCe-8693) was established from a metastatic lymph node of the surgical specimen from a male adult patient. The cell doubling time was 30.4 hr and the mitotic index was 28.8%. All the cells were of epithelial type, round and oval in shape. Electron microscopic examination showed large nucleus, clear-cut nucleoli, abundant microvilli and some secretory granules. Chromosomal analysis revealed a mode of 48 per cell. The frequency of colony formation in soft agar was 8%. The cells agglutinated in 1 microgram/ml PHA or ConA. CEA was positive in the cells and in the culture supernatant. When hetero-transplanted to nude mice, HCe-8693 cells grew to form tumor with the same morphology as the original one from the patient with Alcian blue positive material in the cytoplasm. Repeated detection for mycoplasma was negative.

Granular-cell myoblastoma of the cercum: report of a case.

A 9-mm granular-cell myoblastoma of the cecum found incidentally during appendectomy in a 17-year-old-girl is reported. Electronmicroscopic findings favor origin of the granular cells from an undifferentiated mesenchymal (fibroblast-like) cell. Review of the small number of previously reported cases revealed three involving the cecum, one each in the ascending and transverse colon and two in the rectum. Four patients were asymptomatic and their lesions were found incidentally. Three lesions simulated maligancy clinically; these patients underwent right hemicolectomy.

Gastrointestinal stromal tumors of the equine cecum.

Ten cecal tumors were identified during the postmortem examination of seven horse carcasses at slaughter (one horse had three tumors). The multinodular and hemorrhagic tumors ranged from 1 to 10 cm in diameter and consisted of spindle cells arranged in thin, interconnected trabeculae that were often separated by sinuses filled with mucinous fluid, erythrocytes, and siderophages. Spindle cells of all tumors were immunopositive for vimentin, neuron-specific enolase, and c-kit protein but lacked reactivity with antibodies to glial fibrillary acidic protein, S100 protein, and desmin. In one tumor, spindle cells diffusely bound antibodies to synaptophysin. Most tumors contained focal reactivity to smooth muscle actin antibodies; one tumor reacted diffusely. Ultrastructurally, tumor cells were connected by desmosome-like structures and exhibited extended cell processes; some contained dense core neurosecretory granules. These equine stromal tumors appeared to share some characteristics with human gastrointestinal stromal tumors.

Adenosquamous carcinoma of the colon--an immunocytochemical and ultrastructural study. Report of two cases and review of the literature.

This paper presents two cases of adenosquamous carcinoma of the colon and brings to 39 the total number documented in medical literature. The concurrent glandular and squamous differentiation of the tumor cells was demonstrated by immunocytochemistry and electron microscopy. Evaluation of the biologic characteristics of all the reported cases suggests that malignant squamous elements in colonic carcinomas behave more aggressively than their glandular counterparts. In contradistinction from the pure squamous-cell carcinoma of the colon, adenosquamous carcinoma does not show the same predilection for the right colon.

Pleomorphic (giant cell) carcinoma of the intestine. An immunohistochemical and electron microscopic study.

Pleomorphic (giant cell) carcinomas have been described in the lungs, thyroid, pancreas, and gallbladder. Two pleomorphic carcinomas of the small bowel and two of the large bowel are presented. On light microscopic study, the carcinomas were solid, without squamous or glandular differentiation. The tumors were composed of the following three cell types: gemistocytic (giant) cells, smaller polygonal cells, and spindle cells, with identical immunohistochemical reactions. A panel of monoclonal and polyclonal antibodies was applied. All tumors were found to coexpress keratin and vimentin. A positive reaction for neuron-specific enolase (NSE) was found in three tumors and a positive reaction for chromogranin was found in one tumor. On electron microscopic study, intracytoplasmic whorls of intermediate filaments were seen in the perinuclear area. Dense core "neurosecretory" granules were rarely seen. Intestinal pleomorphic carcinomas are histologically identical to pulmonary giant cell carcinomas. The prognosis is poor due to early tumor spread, with only a few months of postoperative survival. The pleomorphic carcinomas have some of the differentiation characteristics of carcinoid tumors and are best regarded as poorly differentiated variants of neuroendocrine carcinomas.

Fibroma of the cecum: report of a case.

A woman suffering from recurrent attacks of abdominal pain was found at operation to have a fibroma of the cecum. The clinical, operative and pathologic findings are described. The medical literature was reviewed and the lesion was found to be uncommon. The importance of specific histologic stains to distinguish the true fibroma from other spindle-cell tumors is stressed.

Mixed adenosquamous carcinoma of the cecum: report of a case and review of the literature.

A case of mixed adenocarcinomatous and squamous carcinomatous tumor of the cecum is reported. The squamous elements present in the tumor had all the criteria of malignancy and not of simple squamous metaplasia (as in adenoacanthoma). The term mixed adenosquamous carcinoma should therefore connote such a tumor.

Malignant fibrous histiocytoma of the cecum: report of a case and review of the literature.

Malignant fibrous histiocytoma (MFH) of the gastrointestinal tract is extremely rare. Here we report a case of MFH of the cecum and review other cases of large bowel MFH in the literature. A 64-year-old man had a large tumor mass in the cecum associated with multiple small peritoneal implants. Histologically, most of the lesion showed inflammatory pseudotumor-like appearance; that is, a mixed proliferation of fibroblasts and myofibroblasts loosely arranged in sweeping fascicles or whorled structures and an admixture of chronic inflammatory cell infiltrate. The myofibroblastic nature of the spindle-shaped cells was confirmed by their immunohistochemical and ultrastructural findings. In addition, there was atypical histiocytic cells infiltrate in some areas and marked lymphatic involvement and lymph node metastasis by such histiocytic cells. These features were interpreted as MFH, although it had to be distinguished from inflammatory fibrosarcoma and leiomyosarcoma. The differential diagnosis is discussed here.

Mixed crypt cell carcinoma. A clinicopathological study of the so-called 'goblet cell carcinoid'.

The clinicopathological features of six appendix and five bowel tumours with features of the so-called 'goblet cell carcinoid' are described. By light microscopy, these tumours were composed predominantly of mucous cells, together with variable proportions of endocrine and Paneth cells. Immunohistochemical and ultrastructural study confirmed this impression and no amphicrine cells were seen. The clinical course of all cases arising in the bowel, and three out of six appendix tumours was characterised by an aggressive behaviour with the development of widespread lymphatic and often intraperitoneal metastasis, but liver metastasis occurred in only one instance. We conclude, both from this study and from a review of the literature, that the 'mixed crypt cell carcinoma' forms a distinct clinicopathological entity justifying separate classification from adenocarcinoma and carcinoid tumour.

Canine intestinal carcinoids.

Intestinal carcinoids were diagnosed in three aged dogs. Two of the neoplasms occurred in the rectum and one at the cecocolic junction. Judged by histologic criteria, all three carcinoids were considered to be malignant. Amyloid was present in both rectal tumors. In each tumor the diagnosis was confirmed by the finding of electron-dense intracytoplasmic secretory granules in the neoplastic cells.