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

Abstract

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.

Thymic Seminoma with Regressive Changes Obscured by Granulomatous Reaction

“…The secondary changes can be classified as regressive changes such as fibrosis, ossification, calcification, cystic degeneration, and reactive changes like florid follicular hyperplasia and epitheloid granulomas. 1,2,4,9 This case demonstrated all of the secondary changes mentioned above, and the difficulty in the diagnosis stemmed from the predominance of the granulomatous reaction and the low number of scattered neoplastic cells within these granulomas. It was impossible to identify the neoplastic component on low-power examination because of the focal distribution of small number of tumour cells, which were masked by the inflammatory reaction.…”

Primary mediastinal seminoma with florid follicular lymphoid hyperplasia: a case report and review of the literature

“…At the time of writing of this paper, there were only three further publications that had reported similar cases. In the 2016, paper by Lee et al had described a single case with the same immuohistological features, except for the presence of a synchronous thymoma [ 14 ]. And finally back in 1986, a paper by Burns et al described three cases all with the same histological features as our case and the case series by Weissferdt et al [ 13 , 15 ] Therefore, to date, including our current case, a total of 11 cases of mediastinal seminoma with florid lymphoid hyperplasia have been reported [ 13 – 15 ].…”

Combined Thymic Epithelial Neoplasms – a Review

“…Thymic epithelial tumors combined with germ cell tumors in the same tumor mass are exceedingly rare. Only four such tumors have been reported in the literature [35][36][37] (Table 4).…”

“…The tumors were large (range: 6 cm to 10 cm) anterior mediastinal masses that on gross examination were circumscribed solid or solid-cystic neoplasms with a gray-red or tan cut surface and areas of hemorrhage and necrosis. [35][36][37] On a microscopic level, the two tumor components may be closely apposed or separate nodules within the same specimen (Figure 6a to f). In addition to the typical features of thymoma, the seminomatous component presented as sheets of epithelioid cells with abundant pale cytoplasm and prominent nucleoli.…”