Combined thymoma-thymic seminoma. Report of 2 cases of a heretofore unreported association

Primary germ cell tumours of the mediastinum: A review with emphasis on diagnostic challenges

This article will review current aspects of the histopathological, immunohistochemical and molecular analysis of primary mediastinal germ cell tumours (PMGCTs) as well as their aetiological, epidemiological, clinical and therapeutic features. PMGCTs represent an important differential diagnosis in the spectrum of mediastinal tumours, and their diagnosis is usually made on small tissue samples from core needle biopsies in combination with diagnostic imaging and serum tumour markers. As in lymphomas, a small biopsy is often the only viable tumour sample available from these patients, as they receive chemotherapy prior to eventual surgical resection. Pathologists therefore need to apply an efficient combination of immunohistochemical markers to confirm the diagnosis of a PMGCT and to exclude morphological mimics.

Combined Thymic Epithelial Neoplasms - a Review

Thymic epithelial neoplasms are the most common tumors of thymic origin but are overall rare in the general population. Their morphologic diversity, ranging from low grade to overtly malignant lesions, along with various histologic growth patterns make them a diagnostically challenging group of tumors. Very occasionally, thymomas and thymic carcinomas may develop in combination with other benign or malignant lesions of thymic origin, further complicating the diagnostic process. The focus of this review lies on the spectrum of thymic epithelial tumors that present with other thymic lesions in the same tumor mass, such as multilocular thymic cysts, neuroendocrine neoplasms, lymphomas, and germ cell tumors among others. Awareness of the existence of such unusual tumors may not only aid in their diagnosis but may also have implications for prognostic and therapeutic purposes.

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.

Spindle cell thymoma (WHO type A) - Choriocarcinoma: An unusual association: A clinicopathological and immunohistochemical study of 3 cases

Three cases of an unusual association between spindle cell thymoma (WHO type A) and choriocarcinoma are presented. The patients are three men between the ages of 58 and 68 years. Clinically, all the patients presented with non-specific symptoms of cough, dyspnea, and chest pain. Clinical history and physical examination did not reveal the presence of any prior malignancy. Diagnostic imaging showed in the three patients the presence of a large anterior mediastinal mass. A core needle biopsy was obtained in the three patients. In two patients the biopsy showed the classic histology of a spindle cell thymoma while in one patient the biopsy showed the association of two tumors - spindle cell thymoma and choriocarcinoma. Surgical resection via thoracotomy was performed in the three patients. The mediastinal tumors measured between 9 and 17 cm in greatest diameter and were described as solid and lobulated with areas of hemorrhage. Histologically, all the tumors showed similar histological features of spindle cell thymoma (WHO type A) associated with a high-grade neoplasm composed of round and multinucleated giant cells compatible with choriocarcinoma. Immunohistochemical stains showed positive staining for keratin 5/6, and p40 in the spindle cell component, while the choriocarcinomatous component showed positive staining for human chorionic gonadotropin and human placental lactogen. The cases herein presented highlight not only the unusual association of spindle cell thymoma and choriocarcinoma but also raises some issues regarding the histogenesis of germ cell tumors, in this case choriocarcinoma.

Thymoma and Synchronous Primary Mediastinal Seminomas with Florid Follicular Lymphoid Hyperplasia in the Anterior Mediastinum: A Case Report and Review of the Literature

Thymoma is the most common neoplasm of the anterior mediastinum and has malignant potential. Germ cell tumors (GCTs) found in the anterior mediastinum are usually benign, and malignant GCTs, such as seminomas, are rare. Histologically, mediastinal seminoma is indistinguishable from testicular seminoma except for site-associated morphological features such as lymphoid follicular hyperplasia. Therefore, excluding metastasis is very important. Recently, we treated a young adult patient with multiple thymic masses that occurred simultaneously. The patient underwent a thymectomy for the removal of the mediastinal masses, one of which was diagnosed as type B2 invasive thymoma, and two of which were diagnosed as primary mediastinal seminomas with massive follicular hyperplasia. The patient received adjuvant chemotherapy after surgical resection. To our knowledge, this is the first description of a thymoma and a mediastinal seminoma occurring simultaneously in the thymus. We present this case along with a literature review.