PMC5634337_01
Ultrasonographic and radiographic findings. (a) A relatively well-demarcated, lobulated, hypoechoic mass with mild heterogeneous echogenicity is noted, showing a focal, ill-defined border, suggesting the possibility of malignancy. (b) Positron emission tomography-computed tomography revealing focal fluorodeoxyglucose uptake in the same lesion
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F1
At the follow-up visit to our department, the size of the mass had increased compared to that of the last examination, and the shape of the mass was more irregular and lobulated, with focal, ill-defined borders, suggesting the possibility of malignant transformation [Figure 1a]. The lesion was diagnosed as low-grade DCIS, and preoperative positron emission tomography/computed tomography revealed focal fluorodeoxyglucose uptake at the same spot [Figure 1b].
Cytologic findings. (a) Conventional smear reveals many chunky clusters of hyperchromatic spindle cells with fascicular arrangement (Pap, x200). (b) The spindle cells have angulated nuclei (x400). (c) Some polygonal-to-epithelioid cells are irregularly aggregated (H and E, x400). (d) Liquid-based preparation reveals an apparent feathery appearance in the periphery with hyperchromatic atypical nuclei (Pap, x200). (e) Some epithelioid cells forming pseudoglandular structure, reminiscent of cribriform ductal carcinoma in situ are noted (Pap, x1K). (f) Immunohistochemical staining for CD56 using the liquid-based preparation shows strong positivity (x1K)
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F2
The conventional smear was highly cellular and consisted of many irregular, "chunky" clusters of cohesive epithelioid-to-spindle cells and a few singly dispersed cells [Figure 2a and b]. Predominantly, the cells showed variably enlarged hyperchromatic angulated nuclei with a high nuclear-to-cytoplasmic ratio [Figure 2b]. In some areas, the tumor cells showed polygonal or epithelioid shape and slightly angulated nuclei with one or two small nucleoli and occasional intranuclear pseudoinclusions [Figure 2c]. In the LBP slides, the tumor cells were tightly aggregated in three-dimensional clusters of metachromatically stained cells with more prominent hyperchromatic nuclei, suggesting a benign or malignant fibroepithelial tumor such as fibroadenoma or phyllodes tumor [Figure 2d]. In a few clusters, several tiny pseudoglandular structures of similar sizes, reminiscent of the cribriform pattern of DCIS, were observed [Figure 2e]. As a result, scattered tumor cells in most clusters showed a strong positivity for CD56, whereas they were negative for the other markers [Figure 2f].
Gross and microscopic findings. (a) A well-demarcated, multinodular, yellow-white solid mass surrounded by a thin fibrous capsule. (b) Microscopically, it is an intraductal hypercellular mass (H and E, x15). (c) Monotonous proliferation of ductal cells showing a striking spindle appearance (x100). (d) Mostly, the tumor cells show a conspicuous whorling, fascicular, and streaming arrangement (x400). (e) Focal area shows an apparent cribriform pattern (x400). (f) Immunohistochemical staining for CD56 is positive and that for p63 reveals partial loss of myoepithelial cells (x400)
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F3
Grossly, the mass was a relatively well-demarcated, multinodular, white-yellow solid mass [Figure 3a]. Microscopically, it was an intraductal mass consisting of proliferation of ductal epithelium with striking spindle features [Figure 3b-d]. In <5% of the total tumor area, a focal area of cribriform DCIS was also found [Figure 3e]. Immunohistochemical staining for p63 revealed diminished numbers of peripheral myoepithelial cells [Figure 3f].