[190] Lipophyllodes of the Breast. A Clinicopathologic Study of 10 Cases Integrated by Molecular Pathology Insights

Janez Lamovec, Pierpaolo Cusati, Stefano Pizzolitto, Giovanna De Maglio, Giovanni Falconieri. Institute of Oncology, Ljubljana, Slovenia; General University Hospital, Udine, Italy; General Hospital, Santiago do Cacem, Portugal

Background: Lipophyllodes tumor (LPT) is a rare, special type of mammary fibroepithelial tumor showing basically the features of phyllodes tumor with a distinctive fatty component featuring mature adipocytes and lipoblasts. Available evidence suggests that most of LPT pursues a benign course, however confirmatory evidence from clinicopathologic investigations of large series integrated by molecular assays are apparently underreported. The aim of this study is to update our knowledge of LPT integrating traditional clinicopathologic assessment with molecular assay for MDM2 gene expression.
Design: We retrieved the archival material of 10 patients with breast LPT and available clinical follow-up. A standard panel of antibodies against cytokeratins, vimentin, actins, S100 protein, desmin, epithelial membrane antigen, estrogen- and progesterone receptors was applied on paraffin sections. Evaluation for the amplification of the MDM2 gene expression was also performed by FISH on 7 cases.
Results: The patients were all women, 39 to 63 years old (median 52 years). Macroscopically the tumors were lobulated, from 4 to 4.5 cm. In one case however it measured 30 cm. Microscopically tissue sections showed an organoid, biphasic growth pattern featuring a pronounced lipomatous component either mature, lipoma-like type or with malignant appearing lipoblasts in a myxoid background simulating myxoid liposarcoma. In 2 cases there was evidence of diverging rhabdomyoblastic differentiation. Follow-up (from 4 to 11 years) is negative for tumor recurrence or metastases in 7 patients. The patient with a 30 cm LPT died of pulmonary metastasis 1 years after mastectomy. 2 patients developed local and isolated metastases and were successfully treated with mastectomy and metastasectomy, respectilvely. No case showed MDM2 gene amplification, including those with an unfavorable follow up.
Conclusions: LPT is clinically comparable with phyllodes tumor inasmuch as it occurs in adult-aged women and presents as a palpable, occasionally huge mass. In most cases, the stromal component features mature fat, however immature and pleomorphic adipocytes may be recognized. The clinical course is difficult to predict on a pathologic basis only: in contrast to common phyllodes tumor increased cellularity, cell pleomorphism and brisk mitotic activity were not associated with an adverse outcome. The absence of MDM2 gene amplification should be also viewed with caution about its prognostic value.
Category: Breast

Monday, March 19, 2012 1:00 PM

Poster Session II # 50, Monday Afternoon


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