Immediate Breast Reconstruction in an 11-year-old Girl with a Large Malignant Phyllodes Tumor

Summary:

Phyllodes tumors are rare fibroepithelial breast tumors representing less than 1% of all breast malignancies, with an extremely uncommon presence in the pediatric population.¹ Although prognosis is favorable following excision given their indolent course, they often grow rapidly and frequently recur. As such, they can present unique oncologic and reconstructive challenges. Herein we present a case of a malignant phyllodes tumor in an 11-year-old girl treated with total skin-sparing mastectomy and adjustable saline implant, and explore the reconstructive challenges of this unique case.

An 11-year-old, otherwise healthy girl presented with a complaint of rapid and asymmetrical growth of her left breast over a 3-month period. The breast enlargement was associated only with tenderness, without overlying skin changes or axillary lymphadenopathy (Fig. 1). She reported menarche at age 10 with otherwise normal early breast development.

Fig. 1.

Preoperative photographs demonstrating marked breast asymmetry with excess diameter and projection of the left breast when compared with right, with firm, mobile intraparenchymal breast mass. Current natural right breast width is extremely narrow at 9 cm.

Physical examination revealed a large, firm, yet mobile mass larger than her developing contralateral breast. Imaging demonstrated an 8 cm, solid heterogeneous mass centered in the retroareolar region and encompassing the entirety of the breast margins. Core needle biopsy revealed biphasic fibroepithelial proliferation with increased stromal cellularity, significant stromal atypia, frequent multinucleated giant cells, and atypical mitotic figures. In conjunction with results of subsequent histology and staining, these findings collectively indicated possible malignant phyllodes.

With presumed malignant phyllodes encompassing the entirety of the breast margins, a wide excision via total skin-sparing mastectomy was recommended for the best opportunity of achieving clear margins. Nipple sparing mastectomy was recommended against, given the immediate retroareolar position of the mass and unacceptably high risk of positive margin and/or NAC necrosis if nipple sparing mastectomy was pursued.

EXCISION AND RECONSTRUCTION

Skin-sparing mastectomy was performed via an elliptical periareolar incision. A poorly defined areolar plane between the subcutaneous tissue and mass on the anterior portion of the breast made for a tedious dissection initially. As the dissection proceeded to the margins of the tumor closer to the chest wall, the mass became intraparenchymal and the dissection could be carried through the natural breast capsule (Fig. 2A).

Fig. 2.

Intraoperative and postoperative photographs. A, Intraoperative photograph of the en-block specimen. Visibly dense 8.5 cm mass is seen within the central and lateral breast with healthy breast tissue seen deep and peripheral to the mass. B, Intraoperative photograph of the immediate reconstruction, with FlexHD Pliable acellular dermal matrix (MTF Biologics, Edison, N.J.) construct sutured into the mastectomy pocket and underlying partially filled Mentor Spectrum adjustable saline implant (Mentor, North Irving, Tex.). C, Three-week postoperative photograph demonstrating the reconstructed breast appearance with 100 mL volume within the adjustable saline implant. Dressing is covering the drain removal site and remote access port.

An immediate reconstruction was performed. Two pieces of FlexHD Pliable Shaped Perforated Acellular Dermal Matrix 11 × 20 cm (manufactured by MTF Biologics, Edison, N.J.) were utilized to create a prepectoral pocket, with goals of redefining the natural breast boundaries, improving soft tissue thickness and support, and providing positional control of the implant (Fig. 2B). Considering her extremely narrow pubescent 9 cm breast width, with unknown potential growth, a Mentor Spectrum 275-330 mL adjustable saline implant with removable remote port, manufactured by Mentor, North Irving, Tex., was selected. The adjustable nature of this implant would allow for serial increases in volume throughout contralateral breast development. The soft, compliant nature was thought to be superior to a traditional breast tissue expander for patient comfort, as well as to avoid potential long-term sequelae such as left chest wall growth disturbance and indentation.²

The implant was inserted into the dermal matrix construct and partially filled with 75 mL of sterile saline, producing adequate contact between the ADM and mastectomy skin flaps to promote soft tissue ingrowth, yet avoiding undue tension on the mastectomy flaps. At 3 weeks postoperative, a 15-mL fill was performed for a total of 100 mL (Fig. 2C). No further fills have been performed to date, as the reconstructed breast has acceptable size and contour match to her natural right breast at this time.

Pathologic evaluation was consistent with malignant phyllodes. H&E demonstrated cellular fibroepithelial neoplasm with leaf-like architecture and largely well-circumscribed, but focally invasive borders. There was marked hypercellularity, stromal expansion, and marked stromal atypia with both pleomorphic and anaplastic forms, showing areas of liposarcomatous-like differentiation. A mitotic rate of 12 mitosis per 10 high power field was observed. Margins were negative but very thin, with the closest being 0.1 cm on deep superior medial margin. The skin and nipple areolar complex were negative for tumor.

Although most literature recommends a 1-cm margin to proceed without additional therapy, this was not feasible in this case given early pubertal breast tissue, which was completely encompassed and displaced by the mass, which immediately abutted her thin breast skin. Radical mastectomy would have been required to achieve a 1-cm margin and was not recommended. Furthermore, in this pediatric patient, the risk of radiation therapy is higher than the risk of tumor recurrence, and hence the patient will be surveilled every 3 months with alternating chest CT and MRI. Serial implant fills will be offered as needed to maintain symmetry with the developing right breast. Exchange to a highly cohesive silicone implant and nipple areolar reconstruction will be offered after right breast development is complete.

DISCUSSION

Phyllodes tumors (PTs) of the breast are rare biphasic fibroepithelial neoplasms initially described in the literature in 1838 by Müller as cystosarcoma phyllodes, due to their leaf-like histologic architecture.³ These tumors have an incidence of only 0.1% of all breast neoplasms, most commonly occurring in women ages 40–50, with few cases reported among adolescents.^4,5

PTs often present as a mobile breast mass with rapid growth. Initial investigation requires multi-modal approaches with clinical and radiologic examination, tissue biopsy, and subsequent excision for definitive diagnosis. Classification by the World Health Organization defines PTs along a spectrum from benign, to borderline, to malignant based on histological features,⁶ with malignant PTs being defined by marked stromal hypercellularity, marked cellular pleomorphism, more than 10 per HPF mitotic figures, infiltrating margins, and marked stromal pattern.⁶

PTs are distinctive on histology; however, they are difficult to diagnose preoperatively,⁷ making treatment recommendations challenging. Although PTs tend to have a good prognosis, the broad range and relatively high rate of local recurrence results in a spectrum of clinical outcomes.⁸ Recurrence rates of benign phyllodes are 10%–17%, borderline 14%–25%, and malignant 23%–30%. As such, the current National Comprehensive Cancer Network Guidelines recommend wide surgical excision without axillary staging, and excision margins of more than 1 cm in cases of borderline and malignant PT.⁹ A positive margin in malignant PT requires immediate return to surgery for re-excision.^1,5 There is controversy regarding adjuvant radiotherapy and chemotherapy, as the benefits of these therapies are unclear.¹⁰

A review of the literature reveals only 20 published cases of PTs in adolescents.^1,11 Of those existing reports, only one describes the reconstructive approach following mastectomy.¹² That case differs from ours in that the patient had reached full skeletal maturity and complete breast development at the time of diagnosis. We herein provide the first report of an immediate, postmastectomy breast reconstruction in a developing child, utilizing a unique adjustable prepectoral construct.

CONCLUSIONS

Primary breast tumors are rare among the pediatric population, and among those, the phyllodes tumor is an uncommon and unique neoplasm producing its own set of diagnostic, oncologic, and reconstructive challenges. The evaluation and findings, surgical resection, and reconstructive approach described in this case report may provide useful insight and perspective for patients and clinicians facing similar challenges in the pediatric population.

ACKNOWLEDGMENT

The views expressed in this article are those of the author(s) and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government.