Tubular complexes of endoplasmic reticulum in lymphoblastic lymphoma: case report

Lennert's lymphoma with giant multivesicular lysosomal bodies optically visible

A case of a 43-year-old male patient with lymphoepithelioid lymphoma is discussed. During the 10-year follow-up of this patient, different biopsy specimens were obtained. Immunohistochemical studies with a complete paraffin panel determined a T-cell nature of the specimens. Electron microscopy showed a peculiar finding in the cytoplasms of the tumoral cells that correlated with optical inclusions observed in optical imprints; these imprints corresponded to lysosomic multivesicular bodies, whose significance is discussed.

Phenotypic and ultrastructural characterization of a medullary thymocyte acute lymphoblastic leukemia with cellular procoagulant activity

The phenotypic and ultrastructural characterization of the blast cells from a T-cell acute lymphoblastic leukemia (T-ALL) that was associated with disseminated intravascular coagulation (DIC) is described. The bone marrow blasts were considered to represent neoplastic medullary thymocytes and were acid phosphatase (+), terminal deoxynucleotidyl transferase (-), acid alpha-naphthyl acetate esterase (-), E-rosette (+) at 4 degrees C and 37 degrees C, Fc- and C3-receptor (-), and cALLA-, Ia-, 9.6+, OKT3+, OKT4+, OKT6+/-, OKT8+, OKT10+. On transmission electron microscopic study, the predominant cell was 6 micron in diameter and possessed an irregular nucleus, moderate-sized nucleolus, marginated heterochromatin, abundant Golgi elements and granules, and prominent intermediate filaments. The cells were analyzed with normal and factor-deficient human plasmas and contained significant amounts of tissue factor-like procoagulant activity. This is the first report of a well-characterized medullary thymocyte T-ALL in which DIC was an accompanying feature, and the first demonstration of tissue factor-like procoagulant activity in acute lymphoblastic leukemia. In view of thrombohemorrhagic phenomena observed in association with other medullary thymocyte leukemias, these findings suggest that tissue factor-like procoagulant activity may be a characteristic of medullary thymocyte-derived lymphoid leukemias.

Kaposi's sarcoma in renal transplant recipients. Ultrastructural and immunoperoxidase study of four cases

Tissues from four cases of Kaposi's sarcoma developing in renal transplant recipients were studied by light and electron microscopic examination and by immunoperoxidase staining for Factor-VIII-related antigen. Ultrastructurally, the tumors in all four cases contained a variable mixture of cells, including endothelial cells, pericytes, fibroblasts, and myofibroblasts. These findings support the origin of Kaposi's sarcoma from primitive vasoformative mesenchyme. Immunoperoxidase staining for Factor-VIII-related antigen was limited to endothelial cells. In one case intracytoplasmic virus-like tubular complexes were seen. The significance of this finding is briefly discussed.

An unusual form of endoplasmic reticulum in mononuclear cells of a giant cell tumor of bone

A peculiar configuration of endoplasmic reticulum (ER) was observed by electron microscopy in some mononuclear cells from a malignant giant cell tumor of bone that had been removed from a cervical vertebral body in a 54-year-old female. The unusual ER consisted of looped, smooth tubules, which originated from poorly developed rough ER present in the tumor cells. The tubular structures were approximately 23 nm in diameter and contained paracrystalline material. The curvilinear tubular ER closely resembles the vermiform tubular structures that have been observed mainly in histiocytes from different clinical forms of histiocytosis X.