Primary myoepithelial carcinoma of the lung: a rare entity treated with parenchymal sparing resection

Primary high-grade myoepithelial carcinoma of the lung: A study of three cases illustrating frequent SMARCB1-deficiency and review of the literature

Primary myoepithelial carcinoma of the lung is exceptionally rare and, hence, remained poorly characterized. We present 3 tumors affecting 2 males and 1 female aged 60 to 84 years. Tumor size ranged from 4 to 10 cm. All presented as well circumscribed non-encapsulated peripheral solitary masses. One patient died postoperatively. The other two were lost to follow-up. Histologically, all tumors were high-grade with predominance of myxoid/chordoid (2) and rhabdoid (1) pattern. Immunohistochemistry (IHC) showed reactivity with vimentin, pankeratin, EMA and smooth muscle actin. Two tumors were SMARCB1-deficient (one with additional loss of SMARCA2 and PBRM1). RNA sequencing revealed no gene fusions. Review of reported cases (total: 16) showed that pulmonary myoepithelial carcinoma affects both sexes equally at a median age of 60 years (24-84), presents predominantly as peripheral masses (69%) in the lower lobes (66%) of smokers (70%) with a median size of 6 cm (1.5-13), and originates as high-grade de novo carcinoma. Forty percent of patients died of disease at a median of 12.5 months (0 to 62). Only 40% of patients were disease free at last follow-up (median, 9.5 months). Prominent lobulation and myxoid stroma were frequent histological features. Most tumors displayed variable combinations of epithelioid, spindle, plasmacytoid, clear, ovoid or round cells. Three of 6 tumors subjected to different RNA panels showed EWSR1 rearrangements (fused to PBX1, ZNF444 or to unknown partner). Two of 3 tumors lacking gene fusions were SMARCB1-deficient (both showed secondary EWSR1 FISH abnormalities due to 22q deletion). Primary pulmonary myoepithelial carcinoma is a rare aggressive malignancy that recapitulates its soft tissue and salivary counterpart. Exclusion of metastasis from other primaries is mandatory and can only be achieved by detailed clinical history and imaging.

Myoepithelial Carcinoma Occurring on the Ascending Aorta

Myoepithelial carcinomas are rare malignant tumors that primarily develop in exocrine glands. We present a case of myoepithelial carcinoma located on the aorta of a 39-year-old Japanese woman. Complete resection of the tumor and aorta was performed using cardiopulmonary bypass. Histologic and immunohistochemical analyses confirmed the diagnosis. The patient was symptom-free after the operation, and no tumor recurrence was observed during 7 years of follow-up. We report a rare myoepithelial carcinoma occurring on the aorta.

Primary pulmonary myoepithelial carcinoma in a young woman: A case report and review of literature

RATIONALE

Myoepithelial carcinoma mainly occurs in the salivary glands, but myoepithelial carcinoma of the lung is extremely rare neoplasm whose biological behavior and clinical course still remain to be fully elucidated. Although considered as low-grade carcinoma, these tumors have a high rate of recurrence or distant metastasis.

PATIENT CONCERNS

To date there are only 11 cases of pulmonary myoepithelial carcinoma reported in the English literature. We report a case of a 24-year-old woman diagnosed with primary pulmonary myoepithelial carcinoma. Informed consent was obtained from the patient.

DIAGNOSES

The tumor derived from superior lobe of left lung and exhibited only myoepithelial differentiation without any ductal formation by histopathological and immunohistochemical analysis.

INTERVENTIONS

The patient underwent the left superior lobe resection. In addition, we first introduce second-generation sequencing technology as a novel strategy for primary pulmonary myoepithelial carcinoma, and these tumors should be included in the differential diagnosis of thoracic neoplasms.

OUTCOMES

The patient was alive with no evidence of disease for up to 12 months.

LESSONS

Individualized treatment is the promising clinical strategy for thoracic neoplasms, and the underlying molecular events should be investigated to find the potential therapeutic targets.

The 2015 World Health Organization Classification of Lung Tumors: Impact of Genetic, Clinical and Radiologic Advances Since the 2004 Classification

The 2015 World Health Organization (WHO) Classification of Tumors of the Lung, Pleura, Thymus and Heart has just been published with numerous important changes from the 2004 WHO classification. The most significant changes in this edition involve (1) use of immunohistochemistry throughout the classification, (2) a new emphasis on genetic studies, in particular, integration of molecular testing to help personalize treatment strategies for advanced lung cancer patients, (3) a new classification for small biopsies and cytology similar to that proposed in the 2011 Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification, (4) a completely different approach to lung adenocarcinoma as proposed by the 2011 Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification, (5) restricting the diagnosis of large cell carcinoma only to resected tumors that lack any clear morphologic or immunohistochemical differentiation with reclassification of the remaining former large cell carcinoma subtypes into different categories, (6) reclassifying squamous cell carcinomas into keratinizing, nonkeratinizing, and basaloid subtypes with the nonkeratinizing tumors requiring immunohistochemistry proof of squamous differentiation, (7) grouping of neuroendocrine tumors together in one category, (8) adding NUT carcinoma, (9) changing the term sclerosing hemangioma to sclerosing pneumocytoma, (10) changing the name hamartoma to "pulmonary hamartoma," (11) creating a group of PEComatous tumors that include (a) lymphangioleiomyomatosis, (b) PEComa, benign (with clear cell tumor as a variant) and

Thoracic Myoepithelial Tumors: A Pathologic and Molecular Study of 8 Cases With Review of the Literature

Thoracic myoepithelial tumors (MTs) are a rare group of tumors showing predominant or exclusive myoepithelial differentiation. They are poorly characterized from both a morphologic and genetic standpoint, in particular features that separate benign from malignant behavior. We examined the histologic and immunohistochemical features of 8 primary thoracic MTs and performed fluorescence in situ hybridization for EWSR1, FUS, PLAG1, and HMGA2, as well as several partner genes. Half (4/8) of the MTs occurred in large airways, and 3 had infiltrative borders. All cases showed immunoreactivity for epithelial markers, in conjunction with S100 protein or myogenic markers. MTs showed morphologic characteristics analogous to MTs at other sites, with no tumors having ductal differentiation. Necrosis and/or lymphovascular invasion was present in 5 cases, with mitotic activity ranging from 0 to 6 mitoses/2 mm² (mean 1). Metastases occurred in 2 cases, and no patients died of disease. Gene rearrangements were identified in half of the cases, with EWSR1-PBX1, EWSR1-ZNF444, and FUS-KLF17 fusions identified in 1 case each and 1 case having EWSR1 rearrangement with no partner identified. No cases were found to have HMGA2 or PLAG1 abnormalities. Compared with fusion-negative tumors, fusion-positive tumors tended to occur in patients who were younger (50 vs. 58 y), female (1:3 vs. 3:1 male:female ratio), and demonstrated predominantly spindle and clear cell morphology. Using a combined data set of our case series with 16 cases from the literature, poor prognosis was significantly correlated with metastases (P=0.003), necrosis (P=0.027), and ≥5 mitoses/2 mm²/10 high-power field (P=0.005). In summary, we identify a subset of thoracic MTs harboring rearrangements in EWSR1 or FUS, and our data suggest that necrosis and increased mitotic activity correlate with aggressive clinical behavior.

Primary myoepithelial carcinoma of the lung: a case report and review of literature

Primary myoepithelial carcinoma of the lung is a very rare tumor arising from the salivary glands of the respiratory epithelium. Since it was first described by Higashiyama et al. in 1998, to the best of our knowledge, only eight actual cases reported in the English-language literature so far. The diagnosis is based entirely on histological and immunohistochemical evaluations. We report a primary myoepithelial carcinoma in a smoker 47-year-old Chinese man, who was referred to our institution for hemoptysis. Computed tomography revealed a 65 mm × 78 mm solid mass in the left lower lobe of lung. The patient underwent the left lower lobe resection. The final histopathological diagnosis was primary myoepithelial carcinoma of the lung. Given the rare occurrences of this tumor, appropriate recommendations for treatment are difficult to formulate. Although classified as low-grade tumor, it has a significant rate of distant metastasis. Herein we report a case of a primary myoepithelial carcinoma of the lung and present a brief review of the literature.

Myoepithelial carcinoma: first case reported in the trachea

Myoepithelial carcinoma displaying exclusively myoepithelial differentiation mainly occurs in the salivary glands and breasts, and is considered extremely rare in the trachea. We present the first documented case of a primary myoepithelial carcinoma in the trachea. The patient was a 23-year-old man who presented with shortness of breath and cough for four months. Bronchoscopy and computed tomographic (CT) scan revealed an intraluminal mass in the trachea. A standard sleeve of trachea resection with end-to-end reconstruction was performed. The tumor was mainly composed of spindle cells and epithelioid cells which exhibited relatively uniform nuclei with finely distributed chromatin and inconspicuous nucleoli, suggesting that it may arise from benign myoepithelioma. Moreover, the tumor displayed marked cytologic atypia and an infiltrative tumor border in some areas, suggesting that it was a malignant tumor. Immunohistochemically, the tumor cells were diffusely positive for AE1/AE3, Vimentin and myoepithelial makers (Calponin, P63 and GFAP). The patient's postoperative course was uneventful with no evidence of recurrence at six months after surgery.