Phyllodes tumors of the breast: clinicopathological analysis of 106 cases from a single institution.

BACKGROUND: Phyllodes tumors (PT) are uncommon biphasic tumors, accounting for less than 1% of all breast primary neoplasms. They form a wide variety of tumors ranging from benign to malignant. Several histological features are used to grade PT into 3 categories: benign (grade I), borderline (grade II) and malignant (grade III) tumors. The aim of our study was to analyse histolopathological, radiological and clinical features of PT from an experience of a single center.

METHODS: It was a retrospective study including 106 patients diagnosed with phyllodes tumors on surgical specimens at the department of pathology, of Hassan II university hospital (Fez, Morocco), from 2009 to 2016.

RESULTS: The mean age was 33.81 years (range of 13-66 years), and the mean age increases with the tumor grade (mean ages of 32.32, 32.87 and 33.65 years respectively for grade I, II and III PT) (p = 0.023); 78 patients (73.58%) had benign PT, 20 (18.86%) had borderline PT and 8 (7.54%) patients were diagnosed with malignant PT. Mostly, the tumor size was <5 cm (63.2%), with BI-RADS 3 (51 patients, 48.11%). The tumor size and the radiological suspicion (ACR/BI-RADS) increased with the tumor grade (p < 0.001). Mitosis count, cellular atypia and stromal cellularity increased with the tumor grade (p < 0.001). Also, the presence of necrosis is associated with malignant PT (p < 0.001). Before surgery, patients had undergone core needle biopsies (CNB) for diagnostic purpose, and the overral sensitivity of this diagnostic procedure was 71.83%. The sentivity of the CNB decreased from grade I PT to grade III PT (from 56.81% to 37.5%), however its specificity increased from grade I to grade III PT (from 59.25% to 100%).

CONCLUSION: Phyllodes tumors of the breast are rare neoplasms with a wide range of clinicopathologic presentations. The core needle biopsy has a good diagnostic sensitivity compared to definitive diagnosis on surgical specimens. There was a statistically significant association between the histological grade of PT and tumor size, radiological suspicion, mitotic count, cellular atypia, stromal cellularity, and tumor necrosis.