Cytogenetic data represent a first line diagnostic aid in gonadal dysgenesis. Generally, the results of a peripheral blood examination reflect the genotypic alteration of the patient. Nevertheless, on occasion one may encounter cases in which clinical and hormonal evidence suggestive of dysgenesis is not accompanied by an anomalous chromosomal finding, upon cytogenetic analysis of the peripheral blood. In these cases, a cytogenetic alteration may be present in cellular components of the ovary and the cutis. In the light of the above, two patients presenting with primary hypergonadotropic amenorrhea, streak gonads and normal peripheral karyotype are described. In one patient presenting with phenotype alterations, ovarian wedge biopsy via laparotomy followed by cytogenetic analysis of ovarian tissue and tissue from the cutis revealed a 45,X/46,XX-type mosaicism. In the other patient, the ovarian cytogenetic findings were unremarkable. Extending chromosomal analysis to several tissues, beyond the peripheral level, in selected cases, is discussed
