Gross genetic alterations and genetic heterogeneity in a periductal stromal tumor of the breast

Abstract

Background Periductal stromal tumors of the breast are exceedingly rare biphasic breast tumors with close morphological relationship to phyllodes tumors. So far, results of genetic analyses on these tumors have not been reported. Case presentation A 50 year old female patient was admitted to the hospital because of a palpable lump in her right breast with a diameter of approximately 5–6 cm which was surgically removed by lumpectomy. Histologic examination revealed a biphasic breast tumor classified as periductal stromal tumor. Array analysis showed a pseudotetraploid tumor with a copy number of 4 for most of the chromosomes. In addition, further changes of chromosomes 1, 5, and 6 were noted but there were no mutations of MED12 as those frequently seen in fibroadenomas or phyllodes tumors. Conclusions The genetic alterations observed indicate karyotypic evolution leading to marked heterogeneity which fits with the tumor´s histologic and cytologic appearance as well as with its malignant behavior. Because of the absence of genetic similarities with phyllodes tumors, the case does not offer evidence for a common entity but rather suggests the existence of two independent entities.

Periductal Stromal Tumor of the Breast with a TERT Promoter Mutation: First Case Report with Comprehensive Molecular Analysis

“…9,10 To our knowledge, a single case report investigating molecular genetic alterations in a periductal stromal tumor exists, which revealed numerous copy number alterations across the genome; however, no MED12 mutations were observed. 14 Given the absence of MED12 mutations, the authors questioned the relation of periductal stromal tumors to phyllodes tumors. Of note, the aforementioned study only performed PCR-based targeted mutational analysis of MED12 and did not sequence additional genes with a multi-gene assay or exome sequencing.…”