The differentiation between a giant fibroadenoma and a phyllodes tumor can be a precarious diagnostic task. However, the distinction between the 2 lesions is important to make, especially since the latter can be malignant and consequently the prognoses differ.
We used various genetic approaches to study a breast tumor showing features of both entities in a 10-year-old girl with a congenital cerebral malformation and diabetes mellitus.
Cytogenetic analysis of cultured tumor cells from 3 different samples revealed a hyperdiploid karyotype: 50-54,XX,+5,+13,+17,+18,+19,+20,+21. High-resolution single nucleotide polymorphism array analysis not only confirmed the trisomies, but also revealed uniparental disomy (UPD) for chromosomes 10, 11, and 22. A consequence of UPD11 was a homozygous deletion in chromosome band 11p15 affecting the PARVA gene; this gene was hemizygously lost in constitutional DNA. Extended analysis of the family revealed that the deletion was inherited, but it did not segregate with breast tumors or congenital malformations.
Combined with the literature data, the findings in the present case strongly suggest that biphasic tumors with high hyperdiploid karyotypes constitute a distinct clinicomorphologic subgroup of benign breast tumors, being particularly common among young children.
Departments of *Clinical Genetics
‡Pediatric Surgery, University and Regional Laboratories, Skåne University Hospital, Lund University, Lund, Sweden
Supported by grants from the Swedish Cancer Society and the Swedish Childhood Cancer Foundation.
The authors declare no conflict of interest.
Reprints: Charles Walther, MD, Department of Clinical Genetics and Pathology, University and Regional Laboratories, Skåne University Hospital, Lund University, Lund 221 85, Sweden (e-mail: email@example.com).
Received September 11, 2011
Accepted September 19, 2012