glycogen and Thymus-Neoplasms

Ten cases of an unusual growth pattern of thymomas are presented. The patients were 8 men and 2 women between the ages of 43 and 62 years. Clinically, 6 patients presented with symptoms of chest pain, cough, and shortness of breath, whereas 4 patients were asymptomatic. Surgical resection of the mediastinal mass was performed in all patients obtaining tumors that varied in size from 4 to 11 cm in greatest dimension. Grossly, the tumors were described as round and well defined, which, at cut surface, showed a firm consistency with a slight lobulated appearance. Areas of necrosis and/or hemorrhage were not present. Histologically, all the tumors showed similar growth pattern characterized by the presence of cells arranged in small cords dissecting fibroconnective tissue and, in some areas, resembling "signet ring" cells. Mitotic activity was not present. Using the Masaoka staging system, 6 cases were in stage I, and 4 cases were in stage II. Histochemical stains for periodic-acid Schiff stain with diastase and mucicarmine were negative for intracytoplasmic mucin. Immunohistochemical studies for CAM5.2 and cytokeratin 5/6 showed a strong positive reaction, whereas thyroid transcription factor 1, epithelial membrane antigen, calretinin, α-fetoprotein, and CD31 were all negative. Follow-up information obtained for 7 patients between 1 and 12 years showed that all these patients are alive and well. The current cases highlight an unusual histologic growth pattern of thymomas that likely can be confused with other tumors of the anterior mediastinum that may require different treatment approaches and carry a different prognosis.

Topics: Adult; Biomarkers, Tumor; Carcinoma, Signet Ring Cell; Desmosomes; Disease-Free Survival; Epithelial Cells; Female; Glycogen; Humans; Male; Middle Aged; Neoplasm Staging; Survival Rate; Texas; Thymoma; Thymus Neoplasms

This report concerns a 49 year old asymptomatic male who had a mediastinal mass demonstrated on routine radiography. A large encapsulated tumour composed of small regular cells arranged in clumps and acini with fine vascular stroma was removed. The differential diagnosis on routine H&E section included parathyroid tumor, medullary carcinoma arising in ectopic thyroid tissue, epithelial thymoma or carcinoid tumor of the thymus. The presence of compressed thymic tissue around the tumor, and of argentaffin granules together with the electron microscopic appearance characteristic of the "enterochromaffin" or "APUD" group of cells allowed the diagnosis of carcinoid tumor of the thymus to be made. Electron microscopy showed that the cell cytoplasm contained electron dense membrane bound granules, together with bundles of microfilaments. Vesicles of smooth surfaced reticulum were present but rough surfaced reticulum was inconspicuous. No desmosomes were demonstrated. Special stains for amyloid and glycogen were negative.

Topics: Amyloid; APUD Cells; Carcinoid Tumor; Cytoplasm; Desmosomes; Endoplasmic Reticulum; Glycogen; Humans; Male; Membranes; Microscopy, Electron; Middle Aged; Thymus Neoplasms

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."

Topics: Cell Nucleolus; Cytoplasmic Granules; Desmosomes; Glycogen; Humans; Lipids; Lymphocytes; Macrophages; Male; Microscopy, Electron; Middle Aged; Myasthenia Gravis; Thymoma; Thymus Neoplasms

Topics: Adult; Basement Membrane; Cell Nucleolus; Desmosomes; Dysgerminoma; Glycogen; Humans; Inclusion Bodies; Male; Microscopy, Electron; Organoids; Testicular Neoplasms; Thymoma; Thymus Gland; Thymus Neoplasms

Topics: Carcinoma, Squamous Cell; Glycogen; Glycolipids; Glycoproteins; Histocytochemistry; Humans; Methods; Muscular Diseases; Myasthenia Gravis; Organ Size; Oxidoreductases; Radiation Effects; RNA; Thymoma; Thymus Gland; Thymus Hyperplasia; Thymus Neoplasms