Background and aims:Precise pathological diagnosis is essential for optimal treatment of thyroid tumors. Ancillary diagnostic markers may be helpful in some cases. The purpose of this study was to compare and evaluate the diagnostic value of CD56, cytokeratin 19 (CK19), and galectin-3 immunohistochemical stainings in distinguishing between papillary carcinoma (PC) and other thyroid malignancies and benign lesions. Methods: The expressions of the three markers were evaluated in PC (n = 67), follicular carcinoma (FC, n = 23), medullary carcinoma (MC, n = 18), anaplastic carcinoma (AC, n = 4), follicular adenoma (FA, n = 15), and nodular hyperplasia (NH, n = 21). Results: Statistical analysis showed significantly different expressions of CD56, galectin-3, and CK19 in PC versus other lesions of the thyroid gland, with the exception of AC. Especially, the sensitivity and specificity of CD56 for diagnosing PC were 92.5% and 86.4%, respectively. The diagnostic specificity of CD56 was higher than that of galectin-3 or CK19 in differentiating PC from other lesions of the thyroid gland. However, its sensitivity was lower than that of galectin-3 or CK19. Conclusion: CD56 turns out to be a good negative marker for diagnosing PC. We suggest that immunohistochemical panels directed at the diagnosis of PC should include CD56 together with galectin-3 and CK19.

MUC5AC and MUC5B were specific makers for non-TRU adenocarcinoma, including both central type adenocarcinoma and mucinous adenocarcinoma. We suggest that non-TRU type adenocarcinoma presents a poorer prognosis, so it should be regarded separately from TRU type adenocarcinoma.

An ectomesenchymal chondromyxoid tumor (ECMT) is a rare neoplasm that exclusively occurs in the anterior dorsum of the tongue. The tumor consists of small round to fusiform or spindle cells with myxoid or chondroid stroma. The tumor consistently shows a positive reaction with glial fibrillary acidic protein antibodies, especially polyclonal antibodies. We report 2 cases of reticulated myxoid tumors arising in the tongue. One tumor occurred in the posterior dorsum of the tongue and another in the anterior. Both tumors showed characteristic morphology of ECMT; however, both were negative for reactions with monoclonal and polyclonal glial fibrillary acidic protein antibodies. On the basis of morphology, they are thought to be belonging to ECMT. Hence, we suggest that ECMT can show broader spectrum of clinical and immunophenotypic feature.

Gastroblastoma is a rare gastric epitheliomesenchymal biphasic tumour composed of spindle and epithelial cells, reported by Miettinen et al in a series of three cases in 2009. All those cases arose in stomachs of young adults. Neither the epithelial nor the mesenchymal component displayed sufficient atypia to diagnose a carcinosarcoma or other malignancy. On immunohistochemistry, the epithelial component expressed cytokeratin, and the mesenchymal component was positive for vimentin and CD10. Miettinen et al designated these neoplasms as gastroblastomas based on their similarities with other childhood blastomas such as pleuropulmonary blastoma and nephroblastoma. This report describes a probable fourth case of this unique type of neoplasm. The present case arose in the gastric antrum of a 9-year-old boy. While similarities were evident with the other cases, there were some differences. The epithelial component was more predominant and showed more mature morphology. Immunohistochemically, the epithelial component showed immunolabelling for c-KIT and CD56. The mesenchymal component was only focally positive for CD10. Ultrastructually, desmosomes and microvilli were found supporting a truly epithelial lesion.

Pure squamous cell carcinoma (SCC) of the stomach is rare and resembles SCC arising elsewhere in the body. The pathogenesis of SCC remains unclear and controversial. At present, <100 cases of primary SCC of the stomach have been reported. The current study presents a case of SCC of the stomach in a 61-year-old male. Total gastrectomy was performed and a 7.0×6.7×4.5-cm tumor with a superiorly located ulcer was identified in the cardia. Upon histological examination, a moderately-differentiated SCC was observed. Tumor cells extended to the serosa, and the perigastric regional lymph node was also involved. No evidence of human papillomavirus (HPV) or Epstein-Barr virus (EBV) infection was identified using a DNA microarray and in situ hybridization, respectively. A post-operative computed tomography scan four months after the gastrectomy revealed tumor recurrence and dissemination of the tumor to the jejunum and pancreas. The patient succumbed to the disease six months later despite the administration of low-dose adjuvant 5-fluorouracil/cisplatin chemotherapy.