Janneke Buist

Cytogenetics of carcinoma in situ of the testis

Carcinoma in situ (CIS) of the testis is the precursor lesion of most testicular germ cell tumors (TGCTs). Karyotyping of CIS is important for a better understanding of the pathogenesis of TGCTs and the progression to invasive cancer. We karyotyped three cases of CIS. All three cases showed a numerical abnormal chromosomal pattern. In one case, two copies of the germ cell tumor marker i(12p) were found.

I(12P)-NEGATIVE TESTICULAR GERM-CELL TUMORS - A DIFFERENT GROUP

Cytogenetic analysis was performed of three seminomas, two primary nonseminomas, and two mature residual teratomas following chemotherapy, all lacking i(12p). Testicular germ cell tumors without an i(12p) may represent a subgroup of germ cell tumors, also in their clinical course, compared with those having i(12p).

Cytogenetics of thyroid follicular adenomas.

We present the results of a cytogenetic study of three cases of follicular adenoma of the thyroid. All three cases had a numerical strongly abnormal karyotype with most abnormalities (eg, +4 or +5, +7, +9, +12, +16) in common, possibly indicating that this cluster of abnormalities might be specific for follicular adenomas. For benign tumors, the three cases showed a remarkably abnormal karyotype. These cases are another example of benign tumors with chromosomal abnormalities that might be specific for follicular adenomas.

Karyotyping and DNA flow cytometry of an orchidoblastoma

The first karyotype of an orchidoblastoma is described. The most striking finding is the absence of the i(12p) marker chromosome, considered specific for testicular germ cell tumors of adults. Differences between infantile and adult testicular germ cell tumors are discussed, as are features that infantile testicular germ cell tumors have in common with extragonadal germ cell tumors.

CYTOGENETIC STUDY OF A COMBINED GERM-CELL TUMOR OF THE TESTIS

The cytogenetic findings in both components of a combined germ cell tumor of the testis are described. The only structural chromosomal abnormality in common was an i(12p).

KARYOTYPING AND DNA FLOW-CYTOMETRY OF METASTATIC OVARIAN YOLK-SAC TUMOR

We karyotyped a metastasis composed of pure yolk sac tumor derived from a primary ovarian germ cell tumor with two components: a dermoid cyst [DNA index (DI) 1.0] and a pure yolk sac tumor (DI 1.88). The metastatic yolk sac tumor had a hypertriploid karyotype and a DI of 1.78 and lacked the germ cell tumor marker i(12p). The absence of this marker in a metastasis from a tumor with a dermoid cyst component might be indicative for a pathogenesis of the yolk sac tumor similar to that of a dermoid cyst and different from that of dysgerminoma.

CYTOGENETIC STUDY OF A NODULAR HYPERPLASIA OF THE THYROID AFTER IRRADIATION FOR HODGKIN'S DISEASE

We describe cytogenetics of a case of nodular hyperplasia of the thyroid with papillary microcarcinoma following radiotherapy for Hodgkins disease. The chromosomal pattern found was very heterogeneous with a clonal abnormality of chromosome 10, among others. Together with some recent data from the literature, this finding may point to an important role of chromosome 10 abnormalities in the pathogenesis of benign and malignant thyroid neoplasms.

A RESIDUAL MATURE TERATOMA WITH A MORE BALANCED KARYOTYPE THAN THE PRIMARY TESTICULAR NONSEMINOMA

We have been able to study the karyotypes and measure the DNA content in both the primary nonseminomatous germ cell tumor of the testes and the residual mature teratoma after chemotherapy of the same patient. Based on these and other studies, the mechanism of therapy-related differentiation in germ cell tumors of the testes is discussed.