Oncocytic low-grade myoepithelial carcinoma ex pleomorphic adenoma - A rare case illustrating key learning points.

BACKGROUND: Oncocytic myoepithelial carcinoma ex pleomorphic adenoma neoplastic is a rare neoplastic event and may not display overt malignant radiological features. METHODS: Using routine histopathology and immunohistochemistry, we characterize a case of low-grade oncocytic carcinoma ex pleomorphic adenoma. RESULTS: The tumor arose in the left parotid gland in a 59 year old female. Computed tomography (CT) imaging demonstrated a well-defined, lobulated, enhancing lesion with relative central stellate hypoenhancement. Histologically, the tumor displayed a multi-nodular, non-destructive, invasive pattern, low mitotic activity (one mitotic figure per 10 high power fields) and a small remnant focus of pleomorphic adenoma. The neoplastic cells showed significant expression of cytokeratin 5/6, S-100 protein, smooth muscle actin and p63. CONCLUSION: Low-grade oncocytic carcinoma ex pleomorphic adenoma is a challenging histopathological diagnosis which can be established with use of immunohistochemistry, generous tumor sampling and recognition of the multi-nodular, non-destructive, pattern of invasion. In the absence of clear-cut tumor encroachment into external structures, its malignant nature may not be easily identified on pre-operative imaging.

Sclerosing microcystic adenocarcinoma of the parotid gland - The first recorded case with histo-cytopathologic correlation and a brief review of the literature.

We present a case of a 1.0 cm primary tumor of the left parotid gland that meets the histological criteria for the recently described entity sclerosing microcystic adenocarcinoma. The patient was a 73-year-old man with a concurrent tonsillar squamous cell carcinoma, and a history of nasopharyngeal carcinoma treated with radiotherapy 23 years prior. Fine needle aspiration cytology demonstrated low-grade biphasic basaloid neoplastic cells arranged in branching sheets and clusters with minimal nuclear pleomorphism. A biphasic appearance was apparent and some of the cell clusters were bordered by a layer of flattened cells with ovoid bland nuclei. On histology, the tumor comprised small bilayered infiltrative tubules, nests, cords, and microcysts. On immunohistochemistry, EMA, SOX-10, P63, and S-100 protein highlighted a dual cell population of luminal and abluminal cells. The cells were negative for CD117, and the Ki-67 proliferation index was low (<5%).

Locally Aggressive Rib Hemangioma With Glomeruloid and Papillary Features - Expanding the Clinicopathologic spectrum of Bone Hemangiomas.

Intra-osseous hemangiomas are uncommon tumors that can present diagnostic and treatment dilemmas. Bone hemangiomas with papillary and glomeruloid growth patterns are exceptionally rare. We present an example of an intra-osseous hemangioma of the rib displaying aggressive features on both radiology and histology. Morphologically, prominent papillary and glomeruloid architectural patterns were observed, in addition to features of cavernous and capillary hemangiomas. Extensive extra-osseous soft tissue involvement was seen. Awareness of the diverse histological features and locally aggressive behavior of bone hemangiomas is important in avoiding over-interpretation as a malignant lesion.

MicroRNA Landscape in Endometrial Carcinomas in an Asian population: Unraveling Subtype-Specific Signatures.

MicroRNAs (MiRNAs) are small, non-coding RNA molecules that function in RNA silencing and post-transcriptional regulation of gene expression. We analyzed the differential expression of miRNAs in 119 endometrial carcinomas, measuring their expression in histological subtypes, molecular subtypes, and tumors with CTNNB1 mutations. Tumors were subdivided into histological and molecular subtypes as defined by The Cancer Genome Atlas. The expression levels of 352 miRNAs were quantified using the PanoramiR panel. Mir-449a, mir-449b-5p, and mir-449c-5p were the top three miRNAs showing increased expression in both endometrioid and de-differentiated carcinomas but were not significantly increased in serous and clear cell carcinomas. The miRNAs with the most increased expression in serous and clear cell carcinomas were miR-9-3p and miR-375, respectively. We also identified 62 differentially expressed miRNAs among different molecular subtypes. Using sequential forward selection, we built subtype classification models for some molecular subtypes of endometrial carcinoma, comprising 5 miRNAs for MMR-deficient tumors, 10 miRNAs for p53-mutated tumors, and 3 miRNAs for CTNNB1-mutated tumors, with areas under curves of 0.75, 0.85, and 0.78, respectively. Our findings confirm the differential expression of miRNAs between various endometrial carcinoma subtypes and may have implications for the development of diagnostic and prognostic tools.