Atypical lymphocytosis resembling non-Hodgkin's lymphoma in peritoneal effusion of infectious mononucleosis: a case report.

Peritoneal effusion appears to be an unusual complication of infectious mononucleosis (IM). The cytological features of peritoneal effusion from a patient affected by IM are presented. The patient was a 21-year-old Japanese woman, with typical and physical findings of IM. Ascites disappeared with resolution of acute IM. The cytospin smears of the ascitic fluid were highly cellular, consisting exclusively of lymphoid cells. Lymphoid cells were composed of large cells with broad basophilic cytoplasm, as well as of small to medium-sized cells having scant cytoplasm and irregularly shaped nuclei. The overall cytomorphological pictures posed serious difficulties in differentiating this condition from those of peripheral T-cell lymphomas manifesting ascites. The majority of atypical lymphocytes, including large cells, expressed CD3 and CD8. The present case indicates that IM should be added to the list of lesions considered for the differential diagnosis of non-Hodgkin's lymphoma of the peritoneal fluid, particularly regarding young adults.

Characterization of eosinophilic hyaline droplets in schwannoma.

In schwannoma, degenerative structures, such as bizarre hyperchromatic nuclei, lipofuscin deposition, hemorrhage, edema, etc., are frequently encountered and are regarded as hallmarks of the benign nature of the neoplasm. Hyaline globules or eosinophilic hyaline droplets (EHDs) have been observed in a large variety of tumors, but they are rare histological manifestations of schwannoma, and the details have not been described as yet. We reviewed 171 cases of schwannoma of conventional histology. We classified them based on the sites where they occurred as follows: 43 acoustic nerves, 9 other cranial nerves, 30 spinal nerve roots, and 89 soft parts. We found EHDs in 8/43, 1/9, 1/30, 2/89 cases, respectively. The droplets were located in both the perikarya and processes. Ultrastructurally, they were electron-dense, round to ovoid organelles, and indistinguishable from secondary lysosomes. MIB-1 immunolabeling of the droplet-bearing cells was almost negative; however, they maintained a viable nuclear appearance without karyorrhexis, pyknosis or apoptotic changes. We therefore conclude that EHD is a new member of degenerative structures in schwannoma, and a hallmark of low growth potential. Furthermore, their higher frequency in acoustic schwannoma may suggest their distinct nature from those originated in the other sites. Possible relevance of EHDs and cellular senescence is also discussed.

Differential labeling of the pinealocytes and pineal interstitial cells by a series of monoclonal antibodies to human pineal body.

Ten hybridomas producing monoclonal antibodies against pineal antigens were established by hybridizing mouse myeloma cells with spleen cells from BALB/c mice immunized with human pineal body homogenate. Seven antibodies immunohistochemically reacted with the pinealocytes and three reacted with the pineal interstitial cells. According to the antibodies applied, the pinealocytes were immunostained in a variable manner; granularly with PP1, PP4 and PP6 antibodies, diffusely with PP2 and PP5, membraneously with PP3, and apically with PP7. The PI1 and P12 antibodies immunolabeled most of the interstitial cells, but PX1 immunolabeled only a small population of these cells. An immunoblotting study indicated that single or multiple polypeptides of the pineal homogenate constituted the antigen epitopes for these antibodies. Most antibodies also immunoreacted with several cell types of the extra-pineal tissues, thus these antibodies are not specific to the human pineal body. This series of monoclonal antibodies should be available for immunohistochemical studies involving the normal and pathological human pineal body.