Hematopoietic precursor cells within the yolk sac tumor component are the source of secondary hematopoietic malignancies in patients with mediastinal germ cell tumors

Acute Mast Cell Leukemia Preceded by Malignant Mediastinal Germ Cell Tumor: A Case Report and Literature Review

Background

Case Presentation

Conclusion

Radiation-Induced Sarcoma following Curative Radiotherapy for Testicular Seminoma: Case Report and Brief Review of the Literature

We report a case of radiation-induced retroperitoneal leiomyosarcoma which developed 37 years after the patient received radiation therapy for testicular seminoma. The sarcoma originated within the para-aortic field, extensively involving neighboring organs, soft tissue and muscle tissues, and could be only partially resected. The absolute number of these secondary sarcomas is low, but the risk of developing such neoplasms calls for awareness in the long-term follow-up of cured seminoma patients.

A common founding clone with TP53 and PTEN mutations gives rise to a concurrent germ cell tumor and acute megakaryoblastic leukemia

We report the findings from a patient who presented with a concurrent mediastinal germ cell tumor (GCT) and acute myeloid leukemia (AML). Bone marrow pathology was consistent with a diagnosis of acute megakaryoblastic leukemia (AML M7), and biopsy of an anterior mediastinal mass was consistent with a nonseminomatous GCT. Prior studies have described associations between hematological malignancies, including AML M7 and nonseminomatous GCTs, and it was recently suggested that a common founding clone initiated both cancers. We performed enhanced exome sequencing on the GCT and the AML M7 from our patient to define the clonal relationship between the two cancers. We found that both samples contained somatic mutations in PTEN (C136R missense) and TP53 (R213 frameshift). The mutations in PTEN and TP53 were present at ∼100% variant allele frequency (VAF) in both tumors. In addition, we detected and validated five other shared somatic mutations. The copy-number analysis of the AML exome data revealed an amplification of Chromosome 12p. We also identified a heterozygous germline variant in FANCA (S858R), which is known to be associated with Fanconi anemia but is of uncertain significance here. In summary, our data not only support a common founding clone for these cancers but also suggest that a specific set of distinct genomic alterations (in PTEN and TP53) underlies the rare association between GCT and AML. This association is likely linked to the treatment resistance and extremely poor outcome of these patients. We cannot resolve the clonal evolution of these tumors given limitations of our data.

Extragonadal germ cell tumors: a review with emphasis on pathologic features, clinical prognostic variables, and differential diagnostic considerations

Extragonadal germ cell tumors (GCTs) are relatively uncommon, but represent 1% to 5% of all GCTs. Their morphology varies widely and includes mature teratoma, immature teratoma, seminoma, yolk sac tumor, embryonal carcinoma, choriocarcinoma, and mixed GCTs. Noncentral nervous system extragonadal GCTs are found in a variety of anatomic locations, but most commonly affect the mediastinum and sacrococcygeal region. Predicting behavior in these tumors can be confusing because it is based on a combination of varying factors including patient age, histologic subtype, anatomic site, and clinical stage. This review attempts to dissect these issues by separating the discussion into 3 age groups: neonatal (congenital), children (prepubertal), and adult (postpubertal). Within each individual age group, we cover the significance of anatomic site, morphology, and staging parameters. In addition, we discuss the spectrum of associated secondary malignancies and their impact on patient outcome. Finally, we provide a detailed survey of differential diagnostic considerations grouped by anatomic site.

Germ cell lineage differentiation in non-seminomatous germ cell tumours

Human germ cell tumours (GCTs) have long fascinated investigators for a number of reasons. Being pluripotential tumours, they can differentiate into both extra-embryonic and embryonic (somatic) tissues. However, it has never been shown convincingly that, in humans, these tumours are truly totipotent and can also give rise to the germ lineage, the third major differentiation lineage occurring early during embryonic life. Using a number of newly available, distinct, immunohistochemical markers, such as OCT3/4, VASA and TSPY, the occurrence of germ cells was investigated in a number of germ cell tumours. Development of germ cells was identified in three independent non-seminomas, including two pure yolk sac tumours and one mixed tumour composed of yolk sac tumour and immature teratoma. Our finding indicates a previously unknown totipotent potential of human GCTs and raises the question of whether, under certain culture conditions, primordial germ cells could be derived from human GCT cell lines.