Bilateral synchronous benign phyllodes tumors.

Phyllodes tumors (PTs) are rare breast neoplasms that comprise < 1% of all surgical breast tumors. They are a type of fibroepithelial lesion and exist along a clinical spectrum of disease alongside more common disease entities including fibroadenomas. PTs are similar to fibroadenomas from a clinical, radiographic, and histologic standpoint, making diagnosis challenging. The distinction has important implications, however, as PTs have a higher risk of recurrence and occasionally metastasis. Whereas bilateral and multifocal presentations are not infrequent with fibroadenomas, they are very uncommon with PTs, and most often are asynchronous and malignant.1–2 An unusual case of PT is discussed here. A 26-year-old female presented for evaluation of bilateral breast masses. She previously had masses excised from both breasts at age 18, however pathology reports were not available. Bilateral breast masses reappeared at age 19 per the patient, and she reported recent expansion in their size and number. The patient was otherwise healthy and nulliparous. She denied any family history of breast cancer. Physical examination revealed multiple mobile, well-circumscribed, non-tender palpable lumps in both breasts. Ultrasound demonstrated 10 right sided lesions and 5 left sided lesions, the largest measuring 5.3cm (Figure 1, a–b). One lesion from each breast (measuring 2.3cm on the right and 2.9cm on the left) was selected for surgical excisional biopsy. Microscopic examination revealed low grade/benign phyllodes tumors bilaterally, with 2 mitoses per high powered field on the right and <1 mitoses per high power field on the left; margins were positive. Figure 1 26-year-old female with multiple bilateral palpable masses at presentation in September 2005. Gray-scale ultrasound image demonstrates two adjacent oval, circumscribed hypoechoic solid masses in the right breast (A, short arrows) and a large lobulated ... Additional imaging was performed and breast MRI identified at least ten remaining breast masses measuring up to 5.6 cm (Figure 1, c–d). No metastatic disease was found. Bilateral mastectomy was recommended given lesion size and multiplicity, however the patient declined. She periodically returned for evaluation, and lesions increased in size on follow-up MRI performed three and five years later. Biopsy results of a new 1.9cm mass identified on five-year MRI was consistent with a fibroepithelial tumor with increased stromal cellularity and overgrowth. (Figure 2, a–d). She did become pregnant twice, at age 26 and at age 31, however her pregnancies were not associated with rapid or substantial change in her tumors. She continued to decline surgery until eight years later, when at age 34 she agreed to undergo bilateral mastectomies with immediate reconstruction; she has since had tissue expanders exchanged for permanent implants without difficulty. Mastectomy specimens revealed 13 fibroepithelial tumors in the right breast (0.6 to 5.2cm) and ten in the left breast (0.3 to 5.7cm); several were stromal predominant, and all were classified as fibroadenomas. Figure 2 Follow-up axial contrast enhanced breast MRI demonstrates significant interval increase in a right upper outer quadrant circumscribed mass (long arrows) in 2010 (A) when compared to 2007 (B). Additional masses in the left breast remained relatively stable ... Phyllodes tumors (PTs) are fibroepithelial lesions which most commonly present in 35–55 year-old women as painless unilateral masses ranging from <1 to 40 cm in size.1–3 Fibroepithelial tumors form a continuum classified broadly into four groups including fibroadenoma, low grade/benign PTs, intermediate grade/borderline PTs, and high grade/malignant PTs.3 PTs are rare, comprising fewer than 1% of breast tumors, and the majority (50 to 70%) are low grade/benign.1–3 Distinguishing PTs from fibroadenomas is challenging, however it is useful as PTs have a higher rate of recurrence. 1–2 Both typically form circumscribed masses and can have the same appearance on imaging. Furthermore, it may not be possible to distinguish cellular fibroadenomas from PTs on core needle biopsy. The only means to ensure our patient, who had many lesions with high stromal cellularity, did not have high grade/malignant PT s was with bilateral mastectomies. Multifocality and bilaterality are rare for PTs, and multifocal bilateral PTs are extremely uncommon. Most reported cases of bilaterality present as asynchronous tumors. 1–2;4 Synchronous presentations of bilateral multifocal lesions are almost non-existent; only two prior reports exist to our knowledge. 2–3 The largest number of bilateral phyllodes excised in the literature is 13, performed in a 16 year-old female.3 Our patient had multiple lesions removed, including at least 23 fibroadenomas and 2 PTs. The origin of PTs is an ongoing area of research, with some suggestion that PTs can arise from fibroadenomas and/or from inadequate fibroadenoma resection margins.1–3 Our patient’s lesions could have represented fibroadenomas progressing towards PT formation, especially those with high stromal cellularity. It is difficult to predict local recurrence and distant metastasis based on pathologic features. Positive margins increase recurrence risk, and although retrospective reviews recommend 1 cm margins, positive margins are more likely predictive of recurrence than actual margin length. Other factors important in predicting PT behavior include large tumor size at presentation, infiltrative borders, high stromal cellularity, high mitotic count and necrosis.1–3 Breast conservation with negative margins and mastectomy are both acceptable treatment options. Adjuvant therapies such as radiation and chemotherapy are not routinely used outside of clinical trials.1–2 Given that our patient had 23 fibroepithelial tumors involving bilateral breasts, she was not a candidate for breast conservation and required bilateral mastectomy. We have presented a case of multiple bilateral fibroepithelial tumors arising in a young female over a period of at least 16 years spanning two pregnancies, involving fibroadenomas with increased stromal cellularity and synchronous bilateral PTs. Although the patient declined surgery for eight years, she eventually had successful surgical treatment.