Myoepithelial carcinoma with rhabdoid features in the maxillary sinus: Immunohistochemical and in situ hybridization analysis of a rare case

Top Ten Differentials to Mull Over for Head and Neck Myoepithelial Neoplasms

BACKGROUND

Myoepithelial neoplasms of the salivary gland are benign or malignant neoplasms composed exclusively of neoplastic myoepithelial cells. These tumors, including the benign myoepithelioma and the malignant counterpart myoepithelial carcinoma, exhibit a wide range of cytomorphologic features and architectural patterns.

METHODS

Review.

RESULTS

Myoepithelial cells can be epithelial, plasmacytoid, clear cell, spindle cell, and/or oncocytic cell, arranging as trabeculae, solid sheets, nests, cords, and/or single cells. A stromal component is commonly but not universally present, Therefore, their differential diagnoses are quite broad, including salivary gland neoplasms especially those with a myoepithelial component, plasmacytoma, melanoma, and various mesenchymal tumors.

CONCLUSION

In this review, we summarize the characteristic histologic features, useful immunohistochemical panel, and common molecular alterations of myoepithelial tumors and their top differential diagnoses. A logical stepwise algorithmic approach and an immunohistochemical panel to include multiple myoepithelial markers are essential to establish the correct diagnosis.

Malignant Myoepithelioma of the Head and Neck: Demographics, Clinicopathological Characteristics, Treatment, and Prognosis

Malignant myoepithelioma of the head and neck (HNMM) is a rare malignancy, and its characteristics and survival rates have not been well-defined. This study aimed to define the epidemiology of HNMM and identify the prognostic factors associated with the disease. Data on all patients diagnosed with HNMM between 1991 and 2016 were gathered from the Surveillance Epidemiology and End Results (SEER) database. The demographics, clinicopathological characteristics, treatment, and prognoses of the patients were described. Cox regression analysis was used to identify the prognostic factors, and the prognostic nomograms for overall survival (OS) and disease-specific survival (DSS) were constructed. A total of 333 cases of HNMM were identified. The average age at diagnosis was 60.6 years, and 50.1% of the patients were men. After diagnosis, 46.2% of patients underwent surgery alone, 43.5% of patients underwent surgery and radiotherapy, and 3.6% of patients received only radiotherapy. Survival analysis showed that the 5-year OS and DSS for all HNMM patients were 69.7 and 82.1%, respectively. In the multivariate analysis model, the undifferentiated pathological grade (P <0.05) and M1 in the M category (P <0.01) were independent prognostic factors for poor OS and DSS, whereas the use of surgical resection was an independent favorable prognostic factor for both OS and DSS (P <0.05). The prognostic nomograms for OS and DSS prediction were constructed; the C-index values for OS and DSS prediction were 0.78 (95% CI 0.70–0.86) and 0.79 (95% CI 0.67–0.90), respectively. In conclusion, this SEER data-based study demonstrated that HNMM patients often had a favorable prognosis, and distant metastasis, pathological grade, and the use of surgery contributed to their survival. Furthermore, we developed a prognostic nomogram to predict OS and DSS for HNMM patients to aid physicians in the clinical management of this rare disease.

High Grade Myoepithelial Carcinoma of Maxillary Sinus with Extensive Rhabdoid Differentiation and INI-1 Loss: Expanding the Histopathological Spectrum of Sinonasal Carcinoma

Myoepithelial carcinoma (MEC) of salivary gland is an uncommon tumor with no specific age or sex predilection. Most of the cases (~90%) arise in parotid and submandibular glands followed by palate. MEC of maxillary sinus is rare. We describe an extremely rare case of high grade MEC with rhabdoid differentiation and INI-1 loss involving maxillary sinus of an elderly male.

Salivary Duct Carcinoma With Rhabdoid Features-No or Aberrant Expression of E-cadherin and Genetic Changes in CDH1: Immunohistochemical and Genetic Analyses of 17 Cases

Salivary duct carcinoma is a relatively uncommon malignancy of the salivary glands; however, it frequently occurs as a carcinomatous component of carcinoma ex pleomorphic adenoma. We previously reported salivary duct carcinoma with rhabdoid features (SDCRF) as an extremely rare subtype of salivary duct carcinoma, and that it occurred as a salivary counterpart of pleomorphic lobular carcinoma of the breast (PLCB). We collected new cases of SDCRF for this study, in which we examined a total of 17 cases immunohistochemically and genetically. As it is known that PLCB exhibits loss of or aberrant E-cadherin expression and carries nonsense/missense mutations in or deletion of the CDH1 gene, we examined the CDH1 gene status of our SDCRF cases. All of the examined SDCRF cases involved the diffuse proliferation of large ovoid cells with eosinophilic cytoplasm and eccentric nuclei, which displayed reduced cell-cell adhesion. Most cases were positive for pan-cytokeratin, androgen receptor, gross cystic disease fluid protein-15, SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1, and WI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A member 4, whereas they were negative for vimentin. No and decreased/cytoplasmic E-cadherin expression was observed in 11 and 4 of 17 cases, respectively, whereas no and decreased/cytoplasmic β-catenin expression were observed in 10 and 5 of 17 cases, respectively. Among the 11 cases that could be genetically analyzed, a nonsense mutation (1 case), missense mutations (6 cases), and insertions (1 case) were detected in the CDH1 gene. In conclusion, we propose that SDCRF is the salivary counterpart of PLCB due to its morphology and immunophenotype, and the genetic status of CDH1.

Myoepithelial Carcinoma Ex Pleomorphic Adenoma of the Maxillary Sinus: A Case Report and Review of Literature

Myoepithelial carcinoma ex pleomorphic adenoma is defined as a malignant epithelial neoplasm arising from a primary or recurrent benign pleomorphic adenoma. This type of tumor comprises 3.6% of all salivary gland tumors and 12% of malignant ones. Clinically, it most commonly presents as a firm mass in the parotid gland. The development of this neoplasm in the sinonasal and nasopharyngeal regions is extremely rare and only few cases are reported in the literature. The prognosis of myoepithelial carcinoma is variable. Marked cellular pleomorphism, high mitotic rate, and high proliferative activity correspond to a poor prognosis. In this article, the authors report the histopathological features of a clinical case of a 64-years-old patient with a large median maxillary neoplasm diagnosed as myoepithelial carcinoma/ex-pleomorphic adenoma. The tumor was resected and subjected to secondary reconstruction using a revascularized free fibula flap. The myoepithelial derivation of neoplastic cells was demonstrated by immunohistochemical positivity for S-100 protein (strong and diffuse), cytokeratin 14 (strong and diffuse), and GFAP (focal).

Epithelial-Myoepithelial Carcinoma of the Breast with Rhabdoid Features

Epithelial-myoepithelial carcinoma of the breast is a rare biphasic tumor composed of intermixed malignant epithelial and myoepithelial components. Myoepithelial cells are known to adopt varied morphologies, including spindle, chondroid, clear cell, and rhabdoid morphologies, and can represent a diagnostic challenge when isolated on biopsy. Rhabdomyosarcoma, phyllodes tumor, metaplastic carcinoma, and myoepithelial carcinoma are primary breast tumors that all have been shown to exhibit rhabdoid features, whether representing true differentiation or morphological mimic. We here report an epithelial-myoepithelial carcinoma of the breast with rhabdoid features in a 76-year-old woman. The rhabdoid-appearing myoepithelial cells are negative for myogenin, consistent with a rhabdoid-like morphology rather than a true rhabdoid differentiation, comparably to previously described myoepithelial carcinoma with rhabdoid features. To our knowledge, this is the first reported case of epithelial-myoepithelial carcinoma of the breast with rhabdoid features and thus adds another entity to the differential diagnosis of breast lesions with rhabdoid features.