Desmoid-type fibromatosis of the breast: A case report

Abstract

Desmoid-type fibromatosis of the breast (also referred to as desmoid tumor or aggressive fibromatosis) is exceedingly rare. Although it does not metastasize, desmoid-type fibromatosisis is frequently locally aggressive. Recurrence is common (up to 35%), even after presumed total excision of the primary tumor [1]. The breast is an unusual location for the development of this tumor, with relatively few cases reported in the literature. We report a case of desmoid-type fibromatosis in the breast in a 31-year-old female who presented with a four-month history of a palpable left breast mass. Her imaging was discordant, so she underwent surgical excision of the mass. Multiple positive margins were present. She underwent re-excision to the level of the sternum medially. Final pathology showed a focally positive posterior margin, without muscle or fascial involvement. The patient’s case was discussed at the multidisciplinary tumor board conference and no further intervention was recommended. To our knowledge, this is the first case report in the literature in which negative margins were unable to be achieved for desmoid tumors of the breast operatively.

Background

Desmoid-type fibromatosis of the breast (also referred to as desmoid tumor or aggressive fibromatosis) is exceedingly rare. It arises from fibroblasts or myofibroblasts and is similar to desmoid-type fibromatosis of the abdominal wall [1]. The incidence ranges from approximately two to four per million people per year comprising 0.03 percent of all neoplasms [2,3]. Although it does not metastasize, desmoid-type fibromatosisis is frequently locally aggressive. The β -catenin pathway is implicated in sporadic lesions, with dysfunction of the CTNNB1 gene [3]. Recurrence is common, even after presumed total excision of the primary tumor. Sporadic cases are most common, although five to fifteen percent are associated with Familial Adenomatous Polyposis (FAP) [4]. Desmoid-type fibromatosis associated with FAP is more likely to be intra-abdominal, while sporadic tumors more commonly involve the shoulder, hip/buttock area, and the extremities [5]. The breast is an unusual location for the development of this tumor, with relatively few cases reported in the literature. A high index of suspicion is often necessary for diagnosis prior to excisional biopsy. We report a case of desmoid-type fibromatosis in the breast.

Case presentation

A healthy 31-year-old woman presented with a four-month history of a palpable mass in the very medial aspect of her left breast. Her family history was significant for breast cancer in her sister at age thirty-six and in her maternal grandmother in her seventies. The patient’s sister underwent genetic testing and was negative for any deleterious mutations. She reported that she had a negative mammogram two years previously. On physical exam, she had no supraclavicular or axillary lymphadenopathy bilaterally. The breasts were equal and symmetric; nipples were everted with no discharge. Examination of the left breast demonstrated a firm 2 cm mass at the eight o’clock position, in the medial breast, near the sternum. Mammography showed regional spherical calcifications in the left breast that were most likely benign with Breast Imaging-Reporting and Data System (BI-RADS) 3 classification (Fig. 1). However, the mass was so far medial that it was inadequately visualized on mammography. Targeted ultrasound demonstrated a 2.3 cm irregular mass at 9 o’clock, located 13 cm from the nipple, which was highly suggestive of malignancy and classified as BI-RADS 5 (Fig. 2). Evaluation of her axilla was negative.

Ultrasound-guided needle biopsy of the left breast mass was performed, with pathology was reported as benign fibrosis with periductal chronic inflammation. In hindsight, the findings were consistent with desmoid-type fibromatosis. The results were considered discordant which lead to an excisional biopsy. Grossly, a white firm irregular mass with infiltrative margins was seen (Fig. 3). Histologically a paucicellular mass with irregular infiltration into adjacent adipose tissue was present (Fig. 4). High power evaluation showed the mass to be composed of bland spindle cells with wavy nuclei in a collagenous stroma (Fig. 5). An immunohistochemical stain for β -catenin showed nuclear positivity. Multiple positive margins were present. She underwent re-excision lumpectomy to the level of the sternum medially. Final pathology showed a focally positive posterior margin, without muscle or fascial involvement.

The patient’s case was discussed at the multidisciplinary tumor board conference and no further intervention was recommended. This was in accordance with current National Comprehensive Cancer Network guidelines, which state that observation is appropriate in these cases [6]. She was referred for genetic counseling for consideration of APC gene mutation testing, which was subsequently negative. She was advised to undergo regular clinical breast examinations with ultrasound at six-month intervals for at least two years.

Discussion

Desmoid tumors of the breast comprise 0.2 percent of all breast tumors [7]. Histologically, these tumors are characterized by well-differentiated, firm overgrowths of fibrous tissue. In addition to the association with familial adenomatous polyposis, these tumors are associated with trauma to the chest wall, surgery (including liposuction, reduction, and breast implants) and exogenous hormones [8,9]. As a point of interest, our patient had no prior history of breast cancer or breast trauma.

Frequently, patients present with a painless palpable firm mass that may or may not be fixed to the pectoralis muscle. On imaging, desmoid-type fibromatosis typically present as irregular and/or spiculated masses on both mammography and ultrasound.

Desmoid-type fibromatosis displays aggressive local behavior and it is important that re-excision lumpectomy be performed. In a retrospective study done by Neuman et al., it was reported that positive margins are associated with higher rates of recurrence [9]. Although having negative margins reduces the chance that this type of tumor will reoccur, the likelihood of recurrence is unfortunately extremely high. A study by Ballo et al. found that recurrence rates in patients with negative margins to be as high as twenty-seven percent [10]. With this in mind, tumor recurrence surveillance is of high importance, and patients are advised to have regular follow-up breast examinations and imaging for a minimum of two years.

In discussing our patient’s case at the multidisciplinary conference, radiation therapy was considered. However, as the tumor was benign and her first occurrence, this was not recommended.

Adjuvant radiation therapy may be a consideration in patients that develop a recurrence. Data on indications for postoperative radiation in patients with desmoid-type fibromatosis of the breast is scarce. Extrapolations can be made from data on extramammary tumors, which demonstrates a benefit from surgery plus radiation therapy, versus surgery alone. This was especially significant in patients who had positive margins after undergoing surgical excision. The rate of relapse decreased from 59% to 25% with the addition of postoperative radiation [11]. Radiation was showed to be beneficial in both primary and recurrent desmoid-type fibromatosis, so this should be a consideration for patients that have a recurrence. Given our patient’s young age and the morbidity associated with radiation therapy, it was decided that serial observation would be more appropriate.

Tamoxifen therapy is another consideration if a patient has a recurrence. There is a growing body of evidence that Tamoxifen has a demonstrable benefit in patients with desmoid tumors, regardless of receptor status [12]. Brooks et al. showed that in 20 patients taking tamoxifen for mammary desmoid-type fibromatosis, 65% of patients experienced some sort of benefit ranging from stabilization of tumor size to complete regression [13]. There have also been case reports where tamoxifen therapy resulted in complete regression of recurrent desmoid-type fibromatosis, saving the patient the morbidity of any further surgery or radiation therapy [14]. However, there are no large randomized trials demonstrating the efficacy of tamoxifen use after surgical resection. Treating our patient with tamoxifen after surgical excision, given the associated risks and the paucity of data showing clear benefit, was deemed unnecessary, at least at this time.

In summary, desmoid-type fibromatosis of the breast is highly unusual and multiple treatment modalities have been described in the literature. A high index of suspicion may be helpful in correlating needle biopsy and imaging findings. Wide excision with negative margins gives patients the best chances of disease free survival; adjuvant radiation and anti-estrogen therapy are considerations for patients with disease recurrence.