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Cytogenetic analysis was performed of six monophasic synovial sarcomas (four primary, two recurrent tumors) and one recurrent poorly differentiated synovial sarcoma with complex tumor-specific t(X;18). In the complex translocations, besides chromosomes X and 18, the following chromosomes were involved: 1, 3, 5, 15, and 17. In all, taking these results together with findings of 20 previously published synovial sarcoma tumors with complex t(X;18), 13 different chromosomes were involved. Chromosomes 15 (22% of tumors) and 1, 5, and 12 (approximately 11% each) were the most frequently involved in complex translocation, but with different breakpoints. In our laboratories, complex tumor-specific t(X;18) ranged from 2.5% to 11.7% (average 6.5%) of synovial sarcoma karyotypes.

Cytogenetic analyses were performed on 64 nonmalignant thyroid goiters (11 common and 53 multinodular goiters) after short-term culture. The majority of goiters (67%) were characterized by a normal karyotype, but in 5 common (45%) and 16 nodular (30%) goiters, small clones with various numerical and/or structural aberrations were found, in addition to many normal cells. Trisomy or tetrasomy 7 was the most frequent numerical aberration, seen in five cases. Deletion of 18p11 was found in four cases, and in three of them as the sole change. Selection and clonal evolution of aneuploid cells present in nonmalignant goiters could underlie progression into adenoma formation.

Myxoid liposarcomas harbor a unique and specific t(12;16)(q13,p11) chromosomal translocation. The breakpoint has recently been identified, and involvement of the TLS/FUS gene on chromosome 16 and the CHOP gene on chromosome 12 was demonstrated. We report a case of a 45-year-old woman who developed multiple malignant lipomatous tumors of unknown origin and myxoid/round cell histology at different locations. To examine the diagnostic potential of this translocation and to develop a hypothesis on the origin of the tumors, we used cytogenetic and molecular cytogenetic methods (reverse transcription polymerase chain reaction, RT-PCR). We identified a chimeric RNA transcript in the second recurrence in the thigh/groin, as well as in another tumor in the mediastinum, which has an additional sequence of 33 bp, known as fusion transcript type III. Cytogenetic analysis of another tumor in retroperitoneal space revealed a rare type of unbalanced translocation der(16)t(12;16). We hypothesize that these tumors are metastases rather than multicentric tumors. The detection of the chimeric message in the present case is not only useful for differential diagnosis, but also for analyzing the origin of multiple neoplasms.

An undifferentiated embryonal sarcoma (malignant mesenchymoma) of the liver from a 5-year-old girl was found to have near-triploid and near-hexaploid clones with several chromosomal rearrangements. This is the first description of the chromosomal changes in this tumor type.