[Mediastinal germ cell tumors]

The Utility of Fine Needle Aspiration (FNA) Biopsy in the Diagnosis of Mediastinal Lesions

Fine needle aspiration is a minimally invasive, low-morbidity, and cost-efficient technique for the sampling of mediastinal lesions. Additionally, ancillary testing on FNA samples can be used for the refinement of diagnoses and for treatment-related purposes (flow cytometry, cytogenetics, immunohistochemistry, and molecular diagnostics). Mediastinal lesions, however, can show a variety of lineages and morphologic features, giving rise to diagnostic dilemmas. As a result, the differential diagnosis can vary widely and becomes especially challenging due to the smaller sample size on FNA and the variability in component sampling. For appropriate patient management and to determine the correct treatment strategies, accurate pathologic diagnoses are paramount. In this review, we present the cytomorphologic features together with the immunophenotypic findings of mediastinal lesions, with emphasis on the diagnostic challenges and pitfalls in FNA cytology samples, including smears and cell block sections.

[Mediastinal pseudotumor-necrotizing and sclerosing mediastinitis with pseudomembranes]

Mediastinal tumors present a rather rare phenomenon with a variety of underlying causes. Important differential diagnoses include benign and malignant tumors as well as idiopathic sclerosing mediastinitis and parasitic infection.Here, we present the case of a mediastinal pseudotumor with compression of the superior vena cava in a young adult male who spent several years abroad in Brazil. Clinicians suspected either a mediastinal lymphoma, malignant mesenchymal tumor, teratoma, sarcoidosis, or tuberculosis. Biopsy tissue failed to provide a definite diagnosis. The subsequently resected mediastinal mass showed a necrotizing, granulomatous inflammation with prominent eosinophilia and sclerosis. Membranous structures were detected in the necrotic areas, which presented as collagen bundles ultrastructurally. Therefore, these membranes were proven to be constituents of lipid pseudomembranes. Consequently the lesion shows characteristics of sclerosing mediastinitis next to characteristics of adipose tissue necrosis with lipid pseudomembranes. Parasitic infection could not be proven.

[Mediastinal Tumors]

If mediastinal tumours cause symptoms these are related to their anatomical localization or a paraneoplastic syndrome. The differential diagnosis is based on the clinical situation with finding the lesion, and, furthermore, taking into account the age and sex of the patient, and the mediastinal compartment where the lesion is located. Cross-sectional radiographic diagnostic is essential for defining the therapeutic strategy. The anterior mediastinum is dominated by thymic tumours, mediastinal lymphomas, germ cell tumours and ectopic mediastinal poiters. The middle mediastinal compartment is the most frequent place of mediastinal cystic tumours, whereas the posterior mediastinum is the domain of neurogenic tumours. For selected cases a tissue biopsy is required. Surgery is the mainstay for most mediastinal tumours. Median sternotomy is the most frequent conventional surgical technique while minimally invasive surgery with thoracoscopic and above all robot assisted operation techniques are increasingly frequent. Combined chemotherapy and modern radiotherapy are essential components of the comprehensive treatment for mediastinal tumours.

Primary mediastinal germ cell tumours: an immunohistochemical and molecular diagnostic approach

AIMS

Primary mediastinal germ cell tumours (PMGCTs) are rare mediastinal neoplasms and their diagnosis can be challenging due to small biopsy samples. The aim of this study was to elaborate a diagnostic algorithm using immunohistochemical stainings with focus on novel markers and molecular analysis of isochromosome 12p [i(12p)].

METHODS AND RESULTS

Paraffin-embedded tissues of 32 mediastinal tumours were analysed using immunohistochemical stainings for SALL4, LIN28, OCT3/4, D2-40, CD117, SOX17, SOX2, CD30, ß-hCG, GATA3, FOXA2, GPC3, AFP, TdT, NUT and pan-cytokeratin. Quantitative real-time polymerase chain reaction (qPCR) was performed to investigate i(12p) status. Fifteen seminomas, seven teratomas, one yolk sac tumour, one choriocarcinoma and seven mixed PMGCT were diagnosed. Each entity had different immunohistochemical staining patterns which helped to distinguish them: seminoma (OCT3/4, D2-40, CD117, TdT), embryonal carcinoma (OCT3/4, SOX2), yolk sac tumour (FOXA2, GPC3, AFP) and choriocarcinoma (ß-hCG, GATA3). Mature teratomas stained positive for pan-cytokeratin in epithelial components and focally for SALL4, SOX2, GATA3, D2-40 and FOXA2. Furthermore, a NUT carcinoma mimicking a PMGCT was diagnosed showing a strong nuclear SOX2 and speckled nuclear NUT staining. i(12p) was detected in 24 out of 27 PMGCTs [89%].

CONCLUSION

A diagnostic algorithm is of great importance for a reliable diagnosis of PMGCTs in the usually small tissue biopsy samples. Therefore, a combination of three to four antibodies to identify the correct histological subtype is usually necessary in addition to morphological features. The i(12p) status serves as an additional option to underline germ cell origin in selected cases.

Multidisciplinary team for the diagnosis and treatment of 2 cases of primary intestinal yolk sac tumor

Extragonadal primary yolk sac tumor of the intestinal tract origin is exceedingly rare. Through a multiple disciplinary team, the diagnosis and treatment of primary intestinal yolk sac tumor were further defined. We report 2 such cases with detailed histologic and immunohistochemical analysis. The two patients were a 7-year-old girl and a 29-year-old woman. Both of them preoperatively had an elevated serum alpha fetoprotein (AFP) level (≥ 1,210 ng/mL). The tumors are located in the intestine and imaging examination indicated the rectum as the primary site. Grossly the mass was grey-white and crisp texture. Microscopic examination featured reticular, microcystic, macrocystic, papillary, solid, and some glandular patterns. Immunohistochemically, tumor cells of both cases were positive for SALL4, AFP, pan-cytokeratin (AE1/AE3), and glypican-3. Simultaneously, a stain for EMA, OCT4, CD30, HCG, vimentin and CK20 were negative in all 2 neoplasms. The features of morphology, immunohistochemistry, laboratory examinations and imaging studies consist of the diagnosis of primary yolk sac tumor of the intestine.

Primary mediastinal yolk sac tumor treated with platinum-based chemotherapy and extended resection: Report of seven cases

BACKGROUND

Primary mediastinal yolk sac tumor, which is also known as endodermal sinus tumor, is a rare but lethal neoplasm, and it is a kind of mediastinal non-seminomatous germ cell tumor. The current standard treatment in mediastinal non-seminomatous germ cell tumors is chemotherapy combined with postchemotherapy residual mass resection. We report on seven cases of primary mediastinal yolk sac tumor treated with platinum-based chemotherapy and extended resection.

METHODS

We experienced seven cases of primary mediastinal yolk sac tumor between August 2014 and August 2017. All cases had markedly raised α-fetoprotein and normal β-human chorion gonadotropin. Computed tomography scan revealed an anterior mediastinal tumor in all cases. Five patients underwent needle core biopsy, which showed a mediastinal yolk sac tumor. They received preoperative platinum-based chemotherapy and then underwent extended resection, and four of them received postoperative platinum-based chemotherapy. Two other patients did not receive preoperative biopsy, and they underwent surgical extended resection and then received postoperative platinum-based chemotherapy.

RESULTS

Two patients (29%) experienced a postoperative complication, including one pneumonia and one atelectasis. There were no operative deaths. R0 resection was achieved in six patients (86%), and R2 resection was achieved in the other patient. Three patients experienced pulmonary metastases within one year, and two of them soon died. Four other patients were alive without recurrence at the time of writing.

CONCLUSION

Primary mediastinal yolk sac tumor is rare, and the prognosis is poor. A multimodality aggressive approach including adjuvant chemotherapy followed by surgical resection is the optimal treatment and may lead to long-term survival.