Composite follicular variant of papillary carcinoma and mucoepidermoid carcinoma of thyroid gland: a case report

Primary Thyroid Mucoepidermoid Carcinoma (MEC) Is Clinically, Prognostically, and Molecularly Different from Sclerosing MEC with Eosinophilia: A Multicenter and Integrated Study

Mucoepidermoid carcinoma (MEC) and sclerosing MEC with eosinophilia (SMECE) are rare primary thyroid carcinomas. In this study, we aimed to present our multicenter series of MEC and SMECE and integrated our data with published literature to further investigate the clinicopathological characteristics and prognoses of these tumors. We found 2 MECs and 4 SMECEs in our multicenter archives. We performed fluorescence in situ hybridization (FISH) to determine the MAML2 gene rearrangement. We screened for mutations in BRAF, TERT promoter, and RAS mutations using Sanger sequencing and digital polymerase chain reaction. Histopathologically, MECs and SMECEs were composed of two main cell types including epidermoid and mucin-secreting cells, arranged in cords, nests, and tubules. SMECEs were characterized by a densely sclerotic stroma with abundant eosinophils. We did not detect any MAML2 fusion in any of our cases. Two MEC cases harbored concomitant BRAF p.V600E and TERT C228T mutations. RAS mutations were absent in all cases. Concurrent foci of another thyroid malignancy were more commonly seen in MECs (p < 0.001), whereas SMECEs were associated with chronic lymphocytic thyroiditis (p < 0.001). MECs and SMECEs had equivalent recurrence-free survival (RFS) but MECs conferred significantly dismal disease-specific survival (DSS) as compared to SMECEs (p = 0.007). In conclusion, MECs and SMECEs not only shared some similarities but also demonstrated differences in clinicopathological characteristics, prognoses, and molecular profiles. SMECEs had a superior DSS in comparison to MECs, suggesting that they are low-grade cancers. This could help clinicians better evaluate patient outcomes and decide appropriate treatment plans.

Synchronous mucoepidermoid carcinoma and papillary microcarcinomas of the thyroid gland

Thyroid mucoepidermoid carcinoma (MEC) is a rare thyroid malignancy first documented in 1977. The majority of thyroid MECs are indolent, low-grade tumours with excellent prognosis. A woman in her 60s presented with an ongoing sensation of a lump in the left neck. There were no swallowing, voice or airway concerns. Ultrasound of the neck showed an enlarged thyroid with U5 and U3 features on the right and left lobes, respectively. Right fine needle aspiration cytology (FNAC) demonstrated certain features of Hurthle cell or anaplastic carcinoma (Thy5). Left FNAC showed Hurthle cell changes with atypical cells and prominent nucleoli (Thy3a). Following total thyroidectomy, histopathology revealed synchronous right low-grade MEC and left papillary thyroid microcarcinomas (pT2(m) N0 M0) on a background of Hashimoto's thyroiditis. This case adds to the literature and details the key histopathological features for a rare but important differential in patients with thyroid carcinoma due to synchronous histological types.

Salivary-Like Tumors of the Thyroid: A Comprehensive Review of Three Rare Carcinomas

Thyroid carcinomas represent 3.2% of all new cases of cancer in the United States. Whereas most thyroid tumors arise from follicular cells or, less commonly, parafollicular cells, the derivation of some rare primary thyroid carcinoma subtypes is less clear and represents an area of evolving knowledge. Primary thyroid carcinomas that resemble neoplasms characteristic of the salivary glands ("salivary-like" primary thyroid carcinomas) arguably represent some of the most unusual primary thyroid tumors. Herein, we have undertaken a review of the literature in order to present a comprehensive overview of salivary-like primary thyroid carcinomas including: mucoepidermoid carcinoma, sclerosing mucoepidermoid carcinoma with eosinophilia, and secretory carcinoma. Awareness of these unusual, distinct primary tumors is important for timely diagnosis and optimal patient management. This review highlights these three salivary-like carcinomas, with special emphasis on developments since publication of the World Health Organization (WHO) 2017 Classification of Tumours of Endocrine Organs.

Composite poorly differentiated mucoepidermoid carcinoma of the thyroid and follicular variant of papillary thyroid carcinoma. Report of a case and review of the literature

Mucoepidermoid variant of thyroid carcinoma is a rare and complex disease. Securing a diagnosis and formulating an evidence-based treatment plan is challenging. A case report of a patient with the dual pathology of a composite mucoepidermoid carcinoma of the thyroid and a follicular variant of papillary thyroid carcinoma with malignant metastasis is presented in this article. We discuss the challenges in diagnosis, prognostic factors and management of this rare presentation by reviewing current literature.

MAML2 Rearrangements in Variant Forms of Mucoepidermoid Carcinoma: Ancillary Diagnostic Testing for the Ciliated and Warthin-like Variants

Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy. Recent studies have shown that most MECs harbor gene fusions involving MAML2-an alteration that appears to be specific for MEC, a finding that could be diagnostically useful. While most cases of MEC are histologically straightforward, uncommon variants can cause considerable diagnostic difficulty. We present 2 variants of MEC for which MAML2 studies were crucial in establishing a diagnosis: a previously undescribed ciliated variant, and the recently described Warthin-like variant. All cases of ciliated and Warthin-like MEC were retrieved from the archives of The Johns Hopkins Hospital. Break-apart fluorescence in situ hybridization for MAML2 was performed on all cases. One ciliated MEC and 6 Warthin-like MECs were identified. The ciliated MEC presented as a 4.6 cm cystic lymph node metastasis originating from the tongue base in a 47-year-old woman. The Warthin-like MECs presented as parotid masses ranging in size from 1.2 to 3.3 (mean, 2.7 cm) in 4 women and 2 men. The ciliated MEC consisted of macrocystic spaces punctuated by tubulopapillary proliferations of squamoid cells and ciliated columnar cells. The Warthin-like MECs were comprised of cystic spaces lined by multilayered oncocytic to squamoid cells surrounded by a circumscribed cuff of lymphoid tissue with germinal centers. In these cases, the Warthin-like areas dominated the histologic picture. Conventional MEC, when present, represented a minor tumor component. MAML2 rearrangements were identified in all cases. Warthin-like MEC, and now a ciliated form of MEC, are newly described variants of a common salivary gland carcinoma. Unfamiliarity with these novel forms, unanticipated cellular features (eg, cilia), and morphologic overlap with mundane benign processes (eg, developmental ciliated cysts, Warthin tumor) or other carcinomas (eg, ciliated human papillomavirus-related carcinoma) may render these variants susceptible to misdiagnosis. These unusual variants appear to consistently harbor MAML2 fusions-a finding that establishes a clear link to conventional MEC and provides a valuable adjunct in establishing the diagnosis.

Composite Mucoepidermoid Carcinoma and Columnar Cell Variant of Papillary Carcinoma of the Thyroid: A Case Report and Review of the Literature

Primary mucoepidermoid carcinoma (MEC) of the thyroid and columnar cell variant of papillary carcinoma of the thyroid (PCT) are uncommon neoplasms. We report the first case of composite MEC and columnar cell variant of PCT. An 86-year-old man consulted for a 47-mm thyroid nodule, cytologically compatible with PCT. Total thyroidectomy was performed. Histological diagnosis, with support of histochemistry and immunohistochemistry, was mixed primary carcinoma of the thyroid, associating an MEC component with predominantly columnar cell variant of PCT. Sixteen months after surgery and external beam radiation therapy, the patient was free of recurrence or distant metastasis. This case report offers an opportunity to highlight the potential pitfalls concerning the interpretation of mucin histochemistry in thyroid tumors.

Combined papillary and mucoepidermoid carcinoma of the thyroid gland: a possible collision tumor diagnosed on fine-needle cytology. Report of a case with immunocytochemical and molecular correlations

Fine-needle cytology (FNC) is frequently used to diagnose thyroid nodules discovered by palpation or imaging studies. Molecular tests on FNC material may increase its diagnostic accuracy. We report a case of a classic papillary thyroid carcinoma combined with a mucoepidermoid carcinoma correctly identified on FNC. The papillary component had a classic immunophenotype (CK19+, TTF1+), while the mucoepidermoid one was only focally CK19+. Point mutations (BRAF and RAS) and rearrangements (RET/PTC) of the papillary component have been also investigated on FNC samples, with resulting concurrent rearrangements of RET/PTC1 and RET/PTC3, but no point mutations. The histogenesis of combined papillary and mucoepidermoid carcinoma of the thyroid still remains partly unsettled, and further genomic studies are needed to shed some more light on this peculiar neoplasm.

Primary mucoepidermoid carcinoma of the thyroid gland: a report of three cases and review of the literature

Mucoepidermoid carcinoma is the most common salivary gland malignancy and it may arise anywhere that salivary tissue is present. Mucoepidermoid carcinoma has been reported to arise de novo within the thyroid gland, and here, we describe three cases of primary mucoepidermoid carcinoma of the thyroid, including clinical presentation, diagnostic evaluation, and clinical follow-up, along with a discussion of tumor origin and a review of the literature.

The alveolar epithelial differentiation of glandular inner lining cells in a mucoepidermoid carcinoma of the lung: a case report

Mucoepidermoid carcinoma is a common malignant epithelial tumor of salivary glands, but relatively rare in lung. The histological features of mucoepidermoid carcinoma of the lung are similar to its counterpart arising from the salivary glands. Here, we reported a special tumor that occurred in the medial segment of the right lower lobe in a 22-year-old man. This tumor exhibited typical features of mucoepidermoid carcinoma with 3 cell types: squamoid cells, mucin-secreting cells and cells of intermediate type. These 3 types of cells organized into cysts, nests, glands and solid patterns. Specially, the inner lining cells of some glandular structures were uniform cuboidal and hobnail-like, similar to the alveolar epithelial cells. Immunohistochemistry staining revealed that the inner lining cells of glandular structures were positive for thyroid transcription factor-1 and surfactant protein-B, used as markers of alveolar epithelial cells, and were negative for p63. These findings for the first time demonstrated a rare alveolar epithelial differentiation of glandular inner lining cells in a mucoepidermoid carcinoma of the lung.

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A poor prognostic case of mucoepidermoid carcinoma of the thyroid: a case report

Mucoepidermoid carcinoma (MEC) of the thyroid is very rare and low-grade indolent neoplasm. In past reports of the thyroid MEC, only seven cases were described as poor prognosis. A 91-year-old woman presented with a rapidly growing mass of the left upper neck. She was followed thyroid papillary carcinoma (PC) without operation for two years. Fine needle aspiration cytology (FNAC) showed undifferentiated cells. Total thyroidectomy and bilateral neck dissection were performed. In pathological findings, the tumor had two areas of MEC and PC. The boundary of them was mixed. She died of multiple lung metastases only after four months from the operation. We report a rare case of thyroid MEC which had an aggressive behavior and poor prognosis. This case is a precious in that thyroid MEC occurred during observation of PC and suggests a possibility of the transformation from PC to MEC.