Renal medullary carcinoma in a young mixed-race man in Japan.

Renal medullary carcinoma (RMC) is a rare and aggressive cancer associated with the sickle cell trait. The diagnosis of RMC depends on recognition of its histologic features and immunohistochemical deficiency of INI1, but correct diagnosis is sometimes difficult, especially if a patient's information on race, past, and family medical history is unclear. At present, this is the first report on RMC in Japan.

Utility of PAX8 mouse monoclonal antibody in the diagnosis of thyroid, thymic, pleural and lung tumours: a comparison with polyclonal PAX8 antibody.

AIMS: The purpose of this study was to compare the immunohistochemical staining profiles of PAX8-polyclonal, PAX8-monoclonal, PAX5-monoclonal and PAX6-monoclonal antibodies in several histological types of primary thoracic and thyroid tumours. In addition, we analysed PAX8 mRNA expression by using in-situ hybridization. METHODS AND RESULTS: We compared polyclonal PAX8 and monoclonal PAX8, PAX5 and PAX6 antibodies in 962 samples (687 lung carcinomas, 40 malignant pleural mesotheliomas, 138 thymic tumours and 97 thyroid tumours) using the tissue microarray technique. Among thyroid tumours, the monoclonal and polyclonal PAX8 antibodies showed a high positive rate (98.0%). Of 167 polyclonal PAX8 antibody-positive tumours, except for thyroid tumours, 54 cases tested positive for PAX5 and/or PAX6 (31 lung carcinomas and 23 thymic tumours). No PAX8 mRNA expression was detected using RNAscope (in-situ hybridization technique) other than in thyroid tumours. A portion of polyclonal PAX8 antibody-positive tumours showed cross-reactivity for PAX5 or PAX6 protein. CONCLUSIONS: Monoclonal PAX8 antibody showed high specificity to thyroid tumours and was superior to the polyclonal antibody.

Mucoepidermoid carcinoma of the lacrimal gland in a patient with the CRTC1-MAML2 fusion gene.

Mucoepidermoid carcinoma (MEC) of the lacrimal gland (LG) is a rare entity. A 47-year-old woman was aware of periorbital swelling for 3 months. At presentation, the patient showed periorbital swelling in the right eye. CT scan showed an isodense mass in the anterior superolateral part of the orbit. MRI delineated the mass as enhancing, extra-conal tumor appearing isointense on T1-weighted sequences, and to be of mixed intensity on T2-weighted sequences. The tumor was totally resected. Microscopically, the tumor tissue was comprised of squamous, epithelioid cells, and cells with plump and clear cytoplasm. Necrosis, neural invasion, or mitotic figures were not observed. Immunohistochemical examination revealed intense staining for cytokeratin 7. A subset of the cells was positively stained with periodic acid-Schiff and mucicarmine stains. Genetic analysis revealed the presence of the CRTC1-MAML2 fusion. The CRTC1-MAML2 fusion may be a useful indicator for the prognosis and planning of adjuvant therapy.

Pyloric Gland Adenoma (PGA) of the Gallbladder: A Unique and Distinct Tumor from PGAs of the Stomach, Duodenum, and Pancreas.

Twenty-four surgically resected, gallbladder pyloric gland adenomas (GB-PGAs) were examined and their features were compared with the reported features of stomach, duodenum, and pancreatic PGAs to better understand GB-PGAs. Clinical information on background gallbladder lesions and histologic data, including tumor grade, existence of squamoid morules, intratumoral cholesterosis, and intracytoplasmic mucins were collected. Immunohistochemical staining for MUC2, MUC5AC, MUC6, CDX2, pepsinogen I, p53, and MIB-1/nuclear ß-catenin were evaluated. Targeted mutational analyses of KRAS exon2, GNAS exon 7, and CTNNB1 exon 3 were conducted. We found that 29.2% of the GB-PGAs were histologically high-grade dysplasias/carcinomas; 70.8% were low grade; and 20.8% and 33.3% contained squamoid morules and intratumoral cholesterosis, respectively. In addition, 45.8% and 54.2% of GB-PGAs were mucin-rich and mucin-poor types, respectively. Immunohistochemically, MUC6 was diffusely positive in all GB-PGAs; MUC2, MUC5AC, and CDX2 were only focally positive, and no pepsinogen-I positive cells were observed. Nuclear ß-catenin accumulation was observed in all cases; however, the ratio varied among cases. Mucin-poor types were significantly associated with high histologic grade dysplasias/carcinomas and high nuclear ß-catenin labeling indices. Mutational analyses identified CTNNB1 mutations in 100% of GB-PGAs (21/21), KRAS in 4.2% (1/23), and GNAS in 0% (0/22). The present study clarified the unique histologic features, phenotypic differentiation, and molecular statuses frequently associated with GB-PGAs. Altogether, our data suggest that tumorigenesis of GB-PGA is distinct from that of stomach, duodenum, and pancreatic PGAs.