PMC6389554_01
Ultrasound of left breast showing an avascular heterogeneous mass.
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On ultrasound, there was a corresponding heterogenous 3.48 cm mass (Fig. 1).
Malignant phyllodes tumor with ductal carcinoma in situ (DCIS) in surrounding tissue. (A) Low-power magnification image shows a well-circumscribed phyllodes tumor with moderately cellular stroma. (B) Some areas of the phyllodes tumor demonstrated increased periductal stromal cellularity (right) with numerous mitoses (arrows), including atypical forms, and malignant liposarcomatous transformation (left). The stromal cells demonstrate marked cytologic atypia. (C) The subsequent re-excision specimen shows expanded ducts involved by DCIS with solid and cribriform architectural growth and calcifications (arrowheads). (D) Higher magnification of DCIS shows a monotonous population of ductal epithelium with intermediate grade nuclei and focal necrosis (arrowhead). The final re-excision demonstrated similar DCIS with calcifications (not shown).
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Pathology demonstrated no further evidence of the malignant phyllodes tumor, however, incidentally noted a 1.5 cm area of DCIS at the lateral margin, ER+ (90%) and PR- (negative) with a positive margin (Fig. 2).
PMC6389554_02
Ultrasound of right breast showing a heterogeneous, hypoechoic nodule.
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On the diagnostic US, there was a 1.3 cm heterogeneous, hypoechoic nodule at the 3 o'clock position in the periareolar region with no suspicious microcalcifications or architectural distortion (Fig. 3).
Ductal carcinoma in situ (DCIS) within a benign phyllodes tumor. (A) Low-magnification image shows a phyllodes tumor with cellular and expanded stroma (upper right) and ducts expanded by proliferating epithelium (left = DCIS, right = usual ductal hyperplasia). (B) The phyllodes tumor demonstrates infiltrative edges, extending into adjacent adipose tissue (arrows). Only mild stromal atypia was identified. Mitoses were infrequent. (C) Higher magnification of the DCIS demonstrates a monotonous population of epithelial cells with intermediate grade nuclei and rigid cribriform architecture. Minute calcifications are associated with DCIS (arrowhead).
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PR+ (95%) (Fig. 4). DCIS was 2 mm from the anterior margin and >5 mm for all other margins. Phyllodes tumor was <1 mm from anterior and posterior margins, at 1 mm from the medial margin and >5 mm from remaining margins.