Neoplasms result from the progressive and convergent selection of cell populations, but several factors should be considered. On one hand, selection will determine tumor progression and cellular heterogeneity. On the other hand, cellular selection must be related to cell kinetics process.

We reviewed partial trisomy of the long arm of chromosome 7 after a new case was brought to our attention. The clinical differences between the various types of trisomies 7q were evaluated by statistical analysis, and three groups were defined. These groups correspond to the segments q22 or q21 leads to q31, q31 leads to qter, and q32 leads to qter, and would seem to represent three different syndromes, of which one is more serious than the other two.

The relationship among histological features, cell kinetics, and clonality has not been studied in adrenal medullary hyperplasias (AMHs) and phaeochromocytomas (PCCs). Thirty-four PCCs (23 sporadic and 11 MEN-2A (multiple endocrine neoplasia type 2A)-related tumours, the latter associated with AMH) from females were included in this study. Representative samples were histologically evaluated and microdissected to extract DNA and evaluate the methylation pattern of the androgen receptor alleles. At least two tissue samples (from the peripheral and internal zones in each tumour) were analysed with appropriate tissue controls run in every case. The same areas were selected for MIB-1 staining and in situ end labelling (ISEL). Malignant PCCs were defined by histologically confirmed distant metastases. All monoclonal AMH nodules from the same patient showed the same X-chromosome inactivated. Six sporadic PCCs revealed liver metastases (malignant PCC) and eight additional sporadic PCCs showed periadrenal infiltration (locally invasive PCC). All informative PCCs were monoclonal, except for five locally invasive PCCs and one benign PCC that revealed polyclonal patterns. Those cases also showed a fibroblastic stromal reaction with prominent blood vessels, focal smooth muscle differentiation, and significantly higher MIB-1 (126.8+/-29.9) and ISEL (50.9+/-12.8) indices. Concordant X-chromosome inactivation in nodules from a given patient suggests that MEN-2A AMH is a multifocal monoclonal condition. A subgroup of PCCs characterized by balanced methylation of androgen receptor alleles, high cellular turnover, and stromal proliferation also shows locally invasive features.

Hürthle cells are large eosinophilic thyroid cells that contain a large number of mitochondria with a high content of oxidative enzymes. In the last 10 years several reports have emphasized the disagreement over the morphologic features, biologic behavior and treatment of Hürthle cell tumors. The authors reviewed the clinical and pathologic features of 28 patients with Hürthle cell and mitochondrion-rich cell tumors (16 adenomas, 10 follicular carcinomas, and 2 papillary carcinomas) and present electron microscopic, immunohistochemical, and morphometric data. The results suggest that there is a correlation between biologic behavior and pathologic findings, that tumor size should not be considered a special conditioning factor in order to assign a biologic behavior, that nuclear size and anisokaryosis are not an absolute criteria for diagnosing malignancy, and finally, that electron microscopic examination is not useful in separating benign from malignant Hürthle cell tumors.

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