A case of mesothelioma of the peritoneum with asbestosis of the lung was reported. Cytological examination of the peritoneal effusion was performed in this case, which was histologically diagnosed to have malignant mesothelioma.
Characteristic findings of malignant cells are as follows: Tumor cells appeared singly or as groups consisting of a few-many cells. Some of these cells were overlapping each other. The cytoplasm was abundant and its perinuclear area was staind lightly pale or sometimes appeared to be eosinophilic, with a gradual transition to a deep stain at the periphery. Cytoplasmic rims were distinct and sometimes blister-like protrusions appeared after application of the Giemsa' stain.
Nuclei were round or oval and mainly central in location. Their borders were smooth. The chromatin content was increased and chromatin was finely granular with occasional prominent clumps of chromatin.
There could be seen 1-4 small nucleoli and, sometimes, 1-2 large irregular-shaped nucleoli.
Single tumor cells were large and often multinucleated.
Mitoses occured in a small number of tumor cells.
Thick strand-like, dark clumping or finely granular PAS-positive substances were irregularly distributed in the cytoplasm, sometimes the whole of the cytoplasm was stained as a ring. Vacuolated cytoplasm gave a negative reaction to staining. Vacuolated cytoplasm and a part of the cytoplasmic border were stained positive by alcian blue staining.
