Follicular thyroid adenoma: signet ring cell variant.

An unusual case of a microfollicular adenoma of the thyroid gland with signet-ring cells in a 36-year-old euthyroid man is described. Mucin stains demonstrated the presence of mainly neutral glycoproteins with focal participation of acidic groups. Immunohistochemical staining for thyroglobulin was strongly positive. The apparent "mucin secretion" described in these rare neoplasms could be due to the histochemical staining of carbohydrate components or breakdown products of thyroglobulin and colloid. The published work on primary mucin secreting tumors of the thyroid gland is reviewed.

Echinococcosis of bone: clinico-laboratory findings and differential diagnostic problems.

Twenty cases of echinococcosis affecting the skeleton are reported. These cases were diagnosed at the Pathology Department of KAT General Hospital over a 12 year period (1976-1988). The parasitosis involved individual bones or skeletal parts (spine 6, pelvis 6, femur 4, tibia 1, scapula 2 and maxilla 1). The age of the patients ranged from 20-74 years (mean age: 52 years) with preponderance of men. The diagnostic and differential diagnostic problems as well as the therapy and prognosis of this infestation are discussed.

A combined immunohistochemical and histochemical approach on the differential diagnosis of giant cell epiphyseal neoplasms.

The histological similarities and the common localization are the main causes of difficulties concerning the differential diagnosis between giant cell tumor of bone and chondroblastoma. The purpose of the present study was to detect whether histochemistry and/or immunohistochemistry could help to make the distinction between these two entities easier. The study was based on cases of chondroblastoma and giant cell tumor of bone from patients in the 2nd and 3rd decades of life. Histochemical detection of special intracellular and extracellular components (glycogen, glycosaminoglycans) as well as immunohistochemical investigation using various tumor markers (S-100, NSE, a-1-ACT, lysozyme, fibronectin) were performed on parallel paraffin sections. The presence of abundant intracytoplasmic glycogen granules and the immunoreactivity of the cells of chondroblastoma with S-100 and NSE, together with the presence of acidic sulfated glycosaminoglycans in the stroma, could help the differential diagnosis of this tumor from giant cell tumor of bone.

The contribution of immunohistochemistry to the differential diagnosis of primary and metastatic neoplasma of the central nervous system (CNS).

A series of 146 primary and metastatic neoplasms of the CNS were studied with a panel of monoclonal and polyclonal antibodies. The purpose of the study was to evaluate whether immunohistochemistry can help in the differential diagnosis and facilitate a more precise classification of CNS tumors. Neoplastic cells in glial tumors (astrocytomas, ependymomas, oligodendrocytomas) reacted strongly with GFAP. Immunoreactivity with antibodies to neurofilaments helped to distinguish neuronal tumors. Keratin was always positive in metastatic carcinomas, while vimentin positivity characterized mesenchymal differentiation. Other markers such as LCA, S-100, alpha-1-antichymotrypsin, factor VIII, CEA and EMA were variably expressed by tumor cells providing information about cell differentiation and functional status.