The use of immunohistochemistry in the diagnosis of composite and collision tumors: exemplified by pleural mesothelioma and carcinoid tumor of the lung

Malignant mesothelioma cells with characteristic intracytoplasmic vacuolization and lipids

In this brief report, we described some uncommon cytomorphological features of malignant mesothelioma (MM) cells in pleural effusions. The tumor cells exhibited abundant cytoplasmic vacuolization, with presence of single or multiple eccentric nuclei in several cells. In the Giemsa-stained smear, we observed a glossy spherical material in some cells, which tested positive in Sudan III stain. In immunocytochemical analysis, tumor cells were positive for calretinin, podoplanin, epithelial membrane antigen, and methylthioadenosine phosphorylase; tumor cells were negative for BRCA1-associated protein 1, CD68, and desmin. The intracytoplasmic vacuoles were positive for adipophilin expression.

Cytoplasmic Lipid Accumulation Characteristic of the Cribriform Variant of Papillary Thyroid Carcinoma

OBJECTIVE

The purpose of this study was to clarify the diagnostic significance of cytoplasmic lipid accumulation (CLIA) in the cribriform variant of papillary thyroid carcinoma (CV-PTC).

METHODS

We performed a histological, immunohistochemical, and cytological examination of 35 CV-PTC cases at the Kuma Hospital. CLIA was defined as bubble-like multivacuolation in cytoplasm with distinct cell border. We also examined 100 conventional PTC (con-PTC) cases as controls.

RESULTS

Histological analysis showed the presence of carcinoma cells with CLIA in 60.0% of CV-PTC and 5.0% of con-PTC cases. The vacuoles tended to distribute in the subnuclear portion of carcinoma cells showing papillary growth. They were positive for oil red O staining and adipophilin. The carcinoma cells without the vacuoles showed a subnuclear dot-like expression for adipophilin in CV-PTC cases, but not in the con-PTC cases. Cytological analysis showed CLIA in 17 (54.8%) of the 31 CV-PTC cases, but not in the con-PTC cases.

CONCLUSION

This is the first study to report the presence of carcinoma cells with CLIA in CV-PTC. The subnuclear dot-like expression of adipophilin may be characteristic of CV-PTC. These findings might be related to degenerative changes occurring in CV-PTC.

Pulmonary collision tumor consisting of adenocarcinoma and typical carcinoid--a case report and review of literature

Collision tumors are rare in nature. We report a case of a 70-year-old woman who was found to have a new mass in the right lung. Right upper and middle lobectomies with a mediastinal lymph node sampling were performed. Pathological examination of the mass revealed a collision tumor composed of micropapillary adenocarcinoma and typical carcinoid. The neoplastic cells were not intimately admixed with one another. To the best of our knowledge, this case is the first report in the English medical literature of a primary pulmonary collision tumor consisting of micropapillary adenocarcinoma and typical carcinoid.

Case report: Papillary mesothelioma of the peritoneum with foamy cell lining

A 34-year-old female, with a history of continued asbestos exposure, presented with a papillary peritoneal mesothelioma with a diffuse, prominent clear foamy cell change, with microvacuolation in its papillary lining, that expressed cytokeratins 7, 5/6 and calretinin as well as nuclear WT-1 and apical membrane staining for thrombomodulin, podoplanin D2-40 and HBME-1. In contrast, lining cells were CD68 negative. Foamy cell change has been reported in isolated cases as solid cords but not as a diffuse change in the mesothelial papillary lining. This phenomenon prompts differential diagnoses with abdominal and renal papillary clear cell tumours, which were discarded after a characteristic mesothelial immunophenotype was demonstrated.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/4679576081031834.