Phylloid Breast Tumor With Osteocondroid Component: A Clinical Case

Introduction

Phyllodes tumors (PT) are neoplasms composed of a dual epithelial and stromal cell population ^[1] and account for less than 1% of breast tumors. The World Health Organization has divided PTs into three categories: benign, borderline, or malignant, based on five histological parameters: stromal cellularity, stromal atypia, tumor margins, mitotic activity, and stromal hyperplasia ^{[2, 3]} . The category of malignant phyllodes tumors (MPTs) accounts for 8-20% of all PTs ^[4] . MPTs are characterized by marked stromal cellularity, nuclear atypia, increased mitotic activity (≥10 x 10HPF), and infiltrative tumor margins^[5] . In addition, heterologous sarcomatous elements such as osteosarcoma, chondrosarcoma, or liposarcoma have often beenobservedwithinthetumor^[6] andshowarareincidence^[7] . Finally, all types of phyllodes tumors can recur locally^[8] .

OUR CLINICAL CASE A middle-aged woman with no significant medical history showed a nodular area on the upper outer quadrant of her right breast on screening radiology. The biopsy performed on this nodule revealed a phyllodes tumor with histological features of atypia (B4) and indicated complete excision of the lesion for a precise diagnostic classification. Subsequently, our Pathological Anatomy Unit received the entire lesion, described as a fragment of breast parenchyma measuring 4 x 4 x 2 cm with reference threads on the upper, lower, and retroareolar margins. Macroscopic On the cut, a seemingly well-circumscribed neoplasm was found, measuring 3.8 cm in maximum diameter, with increased consistency and a whitish color.

Microscopic Microscopic observation revealed fibroepithelial proliferation, characterized by marked and diffuse hypercellularity of the stromal elements with nuclear atypia (figs. 1, 2) and frequent mitotic figures (fig. 3) equal to 10x10 HPF, areas of necrosis, and poor representation of the ductal component. This proliferation also included an abundant atypical heterologous osteochondroid component (fig. 4). Figure 1. Figure 2. Figure 3. Figure 4. Immunohistochemistry Immunohistochemical investigations showed positivity for CD68 (fig. 5), SATB2 (fig. 6), Vimentin (Fig. 7), Smooth muscle actin (Fig. 8), focal weak positivity for Actin (clone HHF35) (Fig. 9) and P63, negativity for Desmin, Pancytokeratin, Cytokeratin 5/6, estrogen and progestin receptors. The proliferation index, assessed with Ki67, showed moderate expression in neoplastic cells (fig.

10). The morphological findings were consistent with a phylloid tumor with cytological features of malignancy, with clear surgical resection margins. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10.

Discussion

Malignant phyllodes tumors with heterologous differentiation of osteosarcoma and chondrosarcoma are rare and account for 1.3% of all phyllodes tumors. Breast tumors that show bone and cartilage differentiation and are included in the differential diagnosis are: intraductal papilloma with stromal metaplasia, phyllodes cystosarcoma, and stromal sarcoma.^[9] Further differential diagnoses include primary osteosarcoma of the breast, metaplastic carcinoma, and myositis ossificans^{[1] [10][11]} .

Conclusions

Overall, breast sarcomas are biologically aggressive tumors that are rare and require careful study and evaluation of the differential diagnosis, as they are rarely encountered clinically. Pathologists must also consider this rare tumor in their differential diagnosis. They are characterized by the possibility of local recurrence and hematogenous metastasis; therefore, they require careful follow-up over time. Availability Of Data Data supporting the findings of this study are available from the corresponding author upon request. Conflict Of Interest The authors declare that there is no conflict of interest with respect to the publication of this study.

References

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