Cases reported "Thymoma"

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1/10. Epithelio-reticular cell thymoma with lymphocytic "emperipolesis." An ultrastructural study.

    The ultrastructure of an epithelio-reticular cell thymoma associated with myasthenia gravis is described. The neoplastic cells of an epithelio-reticular nature were dominant in the neoplasm, being closely associated with lymphocytes and scattered non-neoplastic macrophages. The thymic epithelio-reticular cell showed abundant glycogen and some lipid droplets inside the cytoplasm, which was vacuolated and had many elongated processes attached to desmosomes and a very prominent nucleolus. The appearance was similar to that of the immature embryonic epithelial cell of the thymus seen in mammals. Very close contacts existed between the thymic lymphocytes and the epithelio-reticular cells, the appearance being suggestive of the phenomenon of "emperipolesis." cell death occurred secondarily through nuclear pyknosis and chromatolysis. Lymphocytic debris appeared inside the epithelio-reticular cells and, to some extent, in the cytoplasm of the mesenchymal marcrophages not directly involved in the phenomenon of "emperipolesis."
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2/10. Ectopic hamartomatous thymoma: a case report with immunohistochemical and ultrastructural studies.

    A case of ectopic hamartomatous thymoma (EHT) arising in the supraclavicular region of a 52-year-old male is presented. The well-defined tumor measuring 1.7x1.5x0.7 cm consisted of three components: spindle cell (70%), epithelial (25%), and adipose (5%). The spindle cell component was characterized by sheet-like, haphazard and short fascicular arrangements of bland spindle cells. Neither mitotic figures nor cellular pleomorphism were found. Admixed with, and adjacent to, the spindle cell areas was an obviously epithelial component of variable appearance, ranging from glandular spaces lined by mainly cuboidal clear cells, irregularly anastomosing cords, and strands of epithelial cells to irregular solid nests of squamous epithelium with dark and clear cytoplasm. Myoepithelial cells were also observed. Immunohistochemically, the spindle cells were strongly and diffusely positive for cytokeratins and some of them were positive for BRST2, alpha-smooth muscle actin, and CD10. The tumor was negative for S-100 protein, glial fibrillary acidic protein, and CD34. Ultrastructurally, tonofilaments and desmosomes were observed in the spindle cells. The findings indicate an epithelial origin. The patient was well without recurrence or metastasis 8 months after excision. Pathologists and clinicians should be aware of the existence of ectopic hamartomatous thymoma in the supraclavicular or suprasternal region and should differentiate it from a high-grade sarcoma, such as biphasic synovial sarcoma or glandular malignant peripheral nerve sheath tumor.
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3/10. Spindle-cell epithelial thymoma. Fine-structural and tumor lymphocyte observations.

    A fine-structural study of a spindle-cell epithelial thymoma in a patient with pemphigus and autoimmune hemolytic anemia is presented and compared with the few previously described. Because light-microscopic features suggested hemangiopericytoma, critical fine-structural comparisons between spindle-cell epithelial thymoma and hemangiopericytoma are detailed. Based upon groups of tonofilaments with desmosomal insertions, abundant well-formed desmosomes, negligible numbers of pinocytotic vesicles, and an absence of myofilaments and dense bodies, an epithelial origin for this tumor is proposed. Langerhans' cell granules, a new observation in thymoma, were found in cells of probably histiocytic origin. Tumor lymphocyte studies revealed that more than 95% of cells formed E rosettes, 36% formed EAC rosettes, yet none contained surface immunoglobulin. The significance of these observations is discussed.
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4/10. Paraneoplastic pemphigus. An autoimmune mucocutaneous disease associated with neoplasia.

    BACKGROUND and methods. We describe five patients with underlying neoplasms in whom painful mucosal ulcerations and polymorphous skin lesions developed, usually with progression to blistering eruptions on the trunk and extremities. Histologic examination showed vacuolization of epidermal basal cells, keratinocyte necrosis, and acantholysis. Immunofluorescence testing revealed atypical pemphigus-like autoantibodies in perilesional epithelium and serum from all five patients. We studied the antigenic specificities of the autoantibodies by indirect immunofluorescence and immunoprecipitation, using extracts of 14C-labeled human keratinocytes. IgG purified from the serum of one patient was passively transferred to four neonatal mice to test for pathogenicity. RESULTS. Immunofluorescence testing showed that the autoantibodies bound to the surface of tissues containing desmosomes, including complex and simple epithelia, and myocardium. An identical and unique complex of four polypeptides with molecular weights of 250, 230, 210, and 190 was immunoprecipitated by all serum samples. The 250-kd polypeptide comigrated with desmoplakin I (a protein found in the desmosomes of all epithelia), and the 230-kd antigen comigrated with the antigen of bullous pemphigoid. Cutaneous blisters, a positive Nikolsky's sign, and epidermal and esophageal acantholysis developed in all mice into which the autoantibody was injected. Electron microscopy showed epidermal acantholysis similar to lesions of experimentally induced pemphigus vulgaris. CONCLUSION. These five patients with cancer had a novel acantholytic mucocutaneous disease characterized by autoantibodies that were pathogenic after passive transfer. The autoantibodies from these patients reacted with an antigen complex composed of desmoplakin I and the 230-kd antigen of bullous pemphigoid and two as yet unidentified epithelial antigens. We suggest the term "paraneoplastic pemphigus" for this disease.
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5/10. Primary thyroid thymoma: a distinct clinicopathologic entity.

    A 51-year-old man presented with a paratracheal tumor. He had undergone resection of a thyroid tumor 15 years previously; at that time, the histologic diagnosis had been anaplastic carcinoma. When the tumor recurred, the presumptive clinical diagnosis was medullary thyroid carcinoma. Histologic examination revealed a poorly differentiated epithelial tumor with immunoreactivity for keratins, carcinoembryonic antigen, and, focally, S-100 protein. The tumor was negative for calcitonin and thyroglobulin. There were scattered lymphocytes and plasma cells. Ultrastructural examination showed elongated epithelial cells with prominent desmosomes and bundles of cytoplasmic tonofilaments but no secretory granules; amyloid was not present ultrastructurally or histochemically. The characteristic ultrastructural and immunocytochemical features and the clinical behavior of this tumor verify the existence of primary thyroid thymoma. This new primary thyroid neoplasm is of clinical importance, considering the more benign behavior of primary thyroid thymoma than of other tumors in the differential diagnosis of this lesion.
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6/10. Mediastinal tumors: ultrastructural and immunohistochemical evaluation of intermediate filaments as diagnostic aids.

    The histogenesis of six mediastinal tumors was investigated ultrastructurally and immunohistochemically using monospecific antibodies against intermediate filament proteins. Four of the tumors, showing different appearances by light microscopy, displayed desmosomes and cytoplasmic tonofilaments, by electron microscopy, compatible with an epithelial thymoma. These cases also showed keratin positivity by immunofluorescence microscopy. One spindle cell tumor showed zonula adherens-type junctions, prominent collections of intermediate filaments, and abundant cytoplasmic neurosecretory granules consistent with a neuroendocrine tumor. In this tumor, neurofilaments could be demonstrated by immunofluorescence microscopy, a feature also consistent with a neuroendocrine tumor. One malignant tumor, lacking tonofilaments and desmosomes but showing a few primitive junctions, did not contain keratin but showed vimentin positivity. This suggests a mesenchymal origin and a diagnosis of primitive sarcoma. These cases illustrate the diagnostic usefulness of electron microscopy and immunohistochemical evaluation of intermediate filaments.
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7/10. Thyroid spindle epithelial tumor with thymus-like differentiation (the "SETTLE" tumor). An immunohistochemical and electron microscopic study.

    An intrathyroid primary epithelial spindle-cell tumor with mucous cysts is described in a 9-year-old child. Histologically, this well-circumscribed tumor exhibited a nodular pattern, a prominent spindle cell component with minimal pleomorphism, and well-differentiated mucinous glands within fibrous bands. The spindle cells demonstrated diffuse immunopositivity for cytokeratin and vimentin. Electron microscopy of tissue sections demonstrated that cells contained bundles of cytoplasmic tonofilaments and numerous desmosomes. The light and electron microscopic features and immunohistochemical profile of this tumor were similar to those of recently described thyroid tumors that have been called "SETTLE" tumors (i.e., spindle epithelial tumor with thymus-like differentiation). These uncommon tumors can be considered intrathyroid thymoblastomas and must be regarded as potentially malignant lesions.
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8/10. Carcinoma arising in ectopic hamartomatous thymoma. An ultrastructural study.

    We present the ultrastructural features of a case of adenocarcinoma arising in ectopic hamartomatous thymoma in a 31 year old man, in the supraclavicular location. The tumor had a cribriform adenomatous component with a granular cell quality and mimicked a metastatic carcinoma. Ultrastructurally, the spindle cell component revealed clusters of tonofilaments and the tumor cells were attached by well developed desmosomes. The cytoplasm of adenocarcinoma cells contained peculiar cup-shaped bodies derived from the endoplasmic reticulum wrapped around the mitochondria.
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9/10. Spindle epithelial tumor with thymus-like differentiation: a case report with cytologic, histologic, immunohistologic, and ultrastructural findings.

    Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a rare and distinctive low-grade neoplasm of thymic or related branchial pouch differentiation. The tumor usually presents in the thyroid or lateral neck of children and adolescents and could mimic spindle-cell carcinoma, synovial sarcoma, or malignant teratoma. We report the clinical, cytologic, histologic, immunohistochemical, and ultrastructural features of a SETTLE present for 10 years in a 15-year-old boy. The fine-needle aspirate, initially interpreted as synovial sarcoma, contained numerous clusters of bland spindle cells, with a few detached sheets of columnar mucous cells in a homogeneous background of dissociated spindle cells. Mitoses, necrosis, and atypia were not present. The excised tumor was a well-circumscribed, white-tan mass, with occasional microcysts. Microscopically, the mass consisted of a lobulated, highly cellular, spindle-cell neoplasm arranged in intersecting, whorled, and storiform fascicles separated by fibrous bands. Entrapped within the fibrous bands were squamous-lined cysts and benign-appearing glands lined by columnar epithelium with goblet cells or ciliated pseudostratified epithelium. Immunohistochemically, the spindle cells showed diffuse reactivity for cytokeratins, smooth muscle actin, muscle-specific actin, and MIC-2, and they were negative for epithelial membrane antigen, calcitonin, and thyroglobulin. Ultrastructurally, numerous perinuclear tonofilaments, some aligned with mature desmosomes, were identified in the spindle cells. Occasional cells showed thin filaments with fusiform dense bodies occupying the peripheral cytoplasm. These findings distinguish SETTLE from ectopic thymoma, synovial sarcoma, medullary carcinoma, and teratoma, and they support a thymic epithelial origin for SETTLE, possibly with myoepithelial differentiation.
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10/10. A spindle cell varient of thymic carcinoid tumor. A clinical, histologic, and fine structural study with emphasis on its distinction from spindle cell thymoma.

    We describe the clinical, histologic, and fine structural features of two thymic carcinoid tumors that had a major spindle cell component, and present the reason for classifying our two cases as variants of thymic carcinoid tumors. These tumors pursued an aggressive clinical course, demonstrated histologic features such as vascular invasion and mitotic activity, ultrastructurally contained numerous dense-core granules, and lacked prominent tonofilaments and well-formed desmosomes. radiotherapy, even for apparently encapsulated cases, may be indicated for this aggressive mediastinal neoplasm, which can be clearly separated from the thymoma by clinical, histologic, and fine structural criteria.
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