Marked infiltration of eosinophils in necrotizing granulomas in the resected hepatic bed after cholecystectomy resulting from gallbladder cancer and metastatic liver cancer is associated with peculiar peripheral eosinophilia.

It is known that after transurethral resection of the prostate (TUR-P) or a bladder tumor (TUR-BT), necrotizing granuloma formation associated with massive eosinophil accumulation can be detected at the site of the scar, revealing marked eosinophilia. This condition is called post-TUR prostatitis or cystitis. In the present study, we noticed a similar phenomenon in five patients who underwent cholecystectomy, of whom four had gallbladder adenocarcinoma and one had metastatic liver cancer originating from the rectum. We detected necrotizing granulomas with massive eosinophil accumulation, associated with marked eosinophilia. To induce these phenomena, the interval between the first operation (i.e., cholecystectomy) and the second operation (i.e., resection of the hepatic bed and extrahepatic bile duct) is very important. If the interval was 1 week, no granuloma formation was detected. On the other hand, if it was more than 2 weeks, the resected hepatic bed contained necrotizing granulomas with substantial eosinophil accumulation combined with an increase in peripheral eosinophilia (up to 34% in one case). Secondary resection was necessary to induce eosinophilia after cholecystectomy. In this sense, malignancies possessed a relationship with delayed eosinophilia. In the granulomas, some foreign body-type multinucleated giant cells were positive for both anti-interleukin (IL)-5 and CD68 antibodies. In sharp contrast, no eosinophilia was detected after cholecystectomy, with or without hepatic resection consequent to severe adhesion. Clinicians as well as pathologists should keep in mind that these peculiar phenomena of eosinophil accumulation surrounding the necrotizing granulomas and peripheral eosinophilia after cholecystectomy could occur.

Immunohistochemical and ultrastructural characterization of the signet-ring cell carcinoma component in a case of urothelial carcinoma of the urinary bladder.

Characterization of the signet-ring cell carcinoma (sig) component of a urothelial carcinoma (UC) in the urinary bladder of a 64-year-old man, obtained by transurethral resection of bladder tumor (TUR-BT), is reported. In the present case, a characteristic sig component was detected in approximately 20% of UC, G2 tissues. The sig cells were morphologically similar to those found in gastric cancers and were positively stained with periodic acid-Schiff reaction and Alcian blue and mucicarmine stains. Immunohistochemically, the sig cells were selectively positive for carcinoembryonic antigen (CEA), MUC2, and MUC5AC. These immunohistochemical characteristics were similar to those of sig cells in the stomach, except for the positivity with MUC2. It is interesting to note that CAM5.2-positive sig cells were surrounded by CAM5.2-positive UC cells in a solid nest with no apparent associated adenocarcinoma element. In addition, the ultrastructure of sig cells showed multivacuolar cytoplasmic mucin, which proved to be similar to the ultrastructure of gastric cancers. In the present case of UC, G2 was associated with a sig component. Regarding the origin of the sig component in the bladder, it has been suggested that MUC2-positive sig cells in the bladder might be derived directly from metaplasia of UC, without an associated adenocarcinoma component. From this perspective, it may be noteworthy that sig cells in the bladder were selectively positive for MUC2, exhibiting common antigenicity with mucous cells of the gastric intestinal metaplasia. Because UC associated with a sig component carries a worse prognosis than ordinary UC, the presence of the sig component in any UC should be evaluated even within TUR-BT tissues, as in the present case.

Immunohistochemical and electron microscopy studies of a case of hyalinizing trabecular tumor of the thyroid gland, with special consideration of the hyalinizing mass associated with it.

Hyalinizing trabecular tumor (HTT) of the thyroid gland is rare and benign, and it neither recurs nor metastasizes. In this lesion, tumor cells are arranged in trabeculae, in association with hyalinizing mass in the stroma. The origin and nature of the hyalinizing mass are still controversial. We report here a case of HTT with cytological, immunohistochemical, and ultrastructural findings, focused in particular on the hyalinizing mass. Cytologically, tumor cells exhibiting many intranuclear cytoplasmic inclusions and nuclear grooves were found in association with light green-positive, irregular, fluffy membranous structures on touch smear. Staining with antibody to collagen type IV was positive in these membranous structures. Histopathologically, tumor cells exhibited many intranuclear cytoplasmic inclusions, and were positive for staining with antibodies to S100 protein, neuron-specific enolase, thyroglobulin, and vimentin. The hyalinizing eosinophilic mass, which was positive for PAS reaction, and for staining by antibody to collagen type IV, gradually increased in the areas surrounding tumor cells. This mass then appeared to replace the tumor cells, and exhibited a peculiar filiform pattern. We demonstrated ultrastructurally that this pattern was composed of long, irregular, fine cytoplasmic processes of tumor cells and basal lamina-like substance in the hyalinizing mass. In fact, the homogeneous hyalinizing mass, similar to basal lamina-like substance, contained many degenerated cytoplasmic processes at the ultrastructural level. These results suggested that the key cytological finding in differentiating HTT from papillary carcinoma is the fluffy membranous structure, although nuclear pseudoinclusions are important as well. The filiform pattern noted at light microscopic level consisted of long cytoplasmic processes of tumor cells and hyalinized mass at the ultrastructural level.