Abstract
A case of primary malignant mesothelioma arising in the pericardium of a 48-year-old female is reported.
Two types of cells, epithelial and nonepithelial form, were detected in the imprinted smears of the tumor tissue. They were arranged in cell clusters and in sheetlike formation. Epithelial cells were composed of roundshaped cytoplasms and centrally located nuclei. Each nucleus had somewhat thickened nuclear rim, evenly scattered fine granular chromatins and 1 or 2 small nucleoli. Nonepithelial cells possessed long elliptical or spindle-shaped cytoplasms and nuclei with fine and coarse chromatins, but the nucleolus was not prominent. The cytoplasms of both cellular types were stained light-green with Papanicolaou stain and showed lace-like fassion. A great majority of these cells had well-defined cellular boundary.
Histologically, the tumor which was composed of cuboidal or polygonal cells in most areas revealed tubulopapillary pattern. Some areas comprising not only round or polygonal cells but also spindle cells assumed solid pavement-like arrangement. These cells were vacuolated and had intercellular spaces with formation of cleft-like or even glandular structures. No fibrosarcomatous pattern was seen.
The tumor cells showed positive staining reaction for colloidal iron and alcian blue, but the reaction was reduced or disappeared by digestion with hyaluronidase. The staining with PAS was weakly positive in the minority of cells, but negative following diastase digestion. The staining with mucicarmine was negative. In cytology, keratin staining exhibited more strongly positive reaction in epithelial cells than nonepithelial cells. In paraffin sections, keratin staining in epithelial cells varied from strongly to weakly positive reaction. Nonepithelial cells, however, displayed negative reaction for keratin in most parts.
Ultrastructurally, the tumor cells were characterized by numerous microvilli, abundant tonofibrils and tonofilaments associated with desmosome, and the presence of basal lamina.
