Synchronous malignant phyllodes tumour and invasive lobular carcinoma-case report and review

Malignant phyllodes tumor and invasive lobular breast carcinoma: Morpho-molecular characterization of an uncommon collision tumor and review of the literature

Phyllodes tumor (PT) of the breast is a biphasic neoplasia composed of mesenchymal and epithelial cells. PTs are graded as benign, borderline or malignant according to histological criteria. Invasive lobular carcinoma (ILC) is a special breast cancer subtype defined by non-cohesive growth and loss of E-cadherin. PT is treated by resection. ILC is treated by resection and adjuvant endocrine therapy with or without chemotherapy. Collision tumors composed of PT and concurrent ILC are rare. Due to their dissociated growth, ILC cells may escape histologic detection when admixed with PTs. Here we report the case of a 71-years-old female diagnosed with a PT/ILC collision tumor. The patient presented with a tumor in the right breast. A core needle biopsy showed mesenchymal spindle cell proliferates suspicious for a PT. The resection specimen confirmed a malignant PT with stromal overgrowth. Unexpectedly, the resection specimen also revealed sparse infiltrates of ILC admixed with the PT. Immunohistochemistry of mesenchymal PT cells and ILC cells was consistent with the histomorphological diagnosis. Molecular analyses demonstrated a IDH1 variant of unknown significance and GNAS gene mutation in microdissected PT tissue. ILC tissue showed wild-type IDH1 and GNAS, but harbored CDH1/E-cadherin and TP53 gene mutations, arguing against clonal relatedness of the two lesions. Review of the literature identified six reported PT/ILC collision tumors, involving three benign, two borderline and one malignant PT. In summary, this is the second report on a malignant PT/ILC collision tumor. Correct histologic diagnosis of PT/ILC collision tumors is clinically relevant, because adjuvant endocrine therapy is mandatory for ILC.

Synchronous Luminal A Ductal Carcinoma In Situ in a Recurrent Benign Phyllodes Tumor Diagnosed Preoperatively: An Unusual Presentation of a Rare Neoplasm

Phyllodes tumor (PT) is a rare benign tumor of the breast with a propensity to recur and metastasize. Ductal carcinoma in situ (DCIS) within PT is an extremely rare finding and is usually diagnosed postoperatively. We present a case of a 36-year-old female with a recurrent lump in her left breast diagnosed as a benign PT. Preoperatively, aspiration cytology revealed DCIS within the known case of recurrent PT. Emergency left modified radical mastectomy was performed due to an uncontrolled sudden hemorrhage from the tumor. Postoperatively, hormonal therapy was started based on immuno-histopathological findings.

DCIS in PT is not encountered frequently and hence no standard management protocol exists for such cases, but when detected by histopathology, the clinical management and prognosis have to undergo a complete change. Preoperative diagnosis and proper individualized management by a multidisciplinary team that ensures clear surgical margins and planned adjuvant therapy play a crucial role in preventing the recurrence of DCIS within PT.

Invasive lobular carcinoma enclosed by a benign phyllodes tumor: A case report

INTRODUCTION AND IMPORTANCE

Phyllodes tumors (PT) account for approximately 1% of all breast tumors. The coexistence of phyllodes tumor and invasive lobular carcinoma in the ipsilateral breast is extremely rare with fewer than six cases reported worldwide in the last 20 years. We hereby present the first in Taiwan.

CASE PRESENTATION

A 43-year-old female was presented with a protruding tumor with bleeding tendency over left breast in 2016. Breast sonography revealed highly suspected malignancy (ACR BI-RADS category 5). Computed tomography scan disclosed a protruding mass occupying the left breast. Core needle biopsy showed a fibroepithelial lesion favoring fibroadenoma. Considering clinicopathological discrepancy, a nipple-sparing mastectomy was conducted. Pathology report revealed a benign PT with an incidental finding of invasive lobular carcinoma (pT1cN0) within the tumor. Due to tumor recurrence, the patient received re-operation of total mastectomy in 2017, and is under regular adjuvant hormonal therapy without cancer recurrence to date.

CLINICAL DISCUSSION

Physicians could easily overlook carcinomas enclosed by PTs due to its occult property. However, when carcinomatous changes arise from within or along with the PT, the proposed therapeutical course may be altered. Moreover, invasive carcinoma components in PTs possess potential for lymph node metastasis. Multidisciplinary cooperation is key in detecting and managing PT with synchronous carcinomatosis.

CONCLUSION

Thorough examination of the excised tumor specimen and ensuring an adequate surgical margin is necessary. Sentinel lymph node biopsy (SLNB) should be considered whenever suspicious clinical features occur in PT patients. This may aid in the detection of microscopic invasive carcinomatous change.