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Desmoid tumours of the breast are rare. Although benign, they can mimic breast cancer on physical examination, mammography and breast ultrasound and can also be locally invasive. Even though they occur sporadically, they can also be seen as a part of Gardner's syndrome. We describe a case of desmoid tumour in a woman with Gardner's syndrome where the lesion was mammographically occult.
A 63-year old woman presented with four months history of a painful left breast lump. She had a screening mammogram seven months ago which was normal. She is known to have Gardner's syndrome and had a total colectomy, she has also had multiple abdominal desmoids excised in the past. On examination there was a 4 cm × 5 cm firm, mobile lump in the left breast. Her mammograms in the clinic were also normal. Ultrasound suggested a benign lesion of the breast and a core biopsy showed it to be a benign spindle cell lesion. She underwent wide local excision of the lump, the intraoperative mammograms of the excised specimen also failed to detect the lesion. Histopathology of the excised specimen confirmed the tumour to be a benign desmoid tumour. She has now been offered radiotherapy and nonsteriodal anti-inflammatory drugs (NSAIDs) to reduce her chances of a local recurrence.
A high index of suspicion and a thorough triple examination protocol is necessary to detect rare lesions like a desmoid tumour which can masquerade as breast carcinoma.
Desmoid tumours (mammary fibromatosis) arise most frequently from the aponeurosis of the rectus abdominal muscle of multipara women.1 The extra-abdominal form is rare and desmoids of the breast may arise in the mammary gland or may occur as an extension of a lesion arising from the muscles of the chest wall.1,2 By definition, fibromatosis is non-encapsulated well-differentiated fibroblastic lesion composed of relatively uniform fibroblasts and collagen and forming a firm, solitary, or multinodular mass with an infiltrative growth pattern. The incidence of mammary desmoid tumours is less than 0.2% of primary breast neoplasms.2,3 In Gardner's syndrome the incidence ranges from 4% to 17%.4 Gardner's syndrome which was first described in 1953 consists of adenomatous polyps of the gastrointestinal tract, desmoid tumours, osteomas, epidermoid cysts, lipomas, dental abnormalities and periampullary carcinomas.5 The incidence of the syndrome is 1:14,025 with an equal sex distribution. It is determined by the autosomal dominant familial polyposis coli gene on chromosome 5.6 Mammography typically shows these tumours as spiculated masses which can resemble malignancy.1,2,7 We report a case of a desmoid tumour in a woman with Gardner's syndrome wherein the tumour was mammographically occult.
A 63-year old Caucasian woman presented to the breast clinic with a four-month history of breast pain and a lump which she noticed on standing up. She had breast pains in the past and was also known to have breast cysts which were managed with aspiration. Her last screening mammogram was seven months ago which was normal. She is known to have Gardner's syndrome. In 1966 at the age of 20, she underwent subtotal colectomy and ileorectal anastomosis for colonic polyposis and diagnosed to be belonging to a family of familial polyposis. A year later she underwent a laparotomy, where a 10 cm desmoid involving the small bowel mesentery was excised. She had a recurrence of the intra-abdominal desmoid in 1978 which measured 15 cm × 7 cm and has been managed expectantly since its diagnosis. She developed a desmoid tumour in her laparotomy scar and this was excised when she had a total abdominal hysterectomy in 1990 for menorrhagia. She again developed a desmoid tumour on her abdominal wall which was excised in 1992. The desmoid has since recurred and is now being managed expectantly. She is on the familial polyposis registry and undergoes regular surveillance gastroscopy and flexible sigmoidoscopy. Recent gastroscopy showed multiple duodenal and periampullary polyps, which are being treated with argon ablation. Her mother had died of breast cancer at the age of 53.
Examination of the left breast showed a well defined lump in the lower outer quadrant measuring about 4 cm × 5 cm. It was firm in consistency, mobile and not clinically attached to the skin or underlying muscle. The right breast, both axillae and both supraclavicular fossae were normal. Abdominal examination revealed a large 15 cm × 8 cm central abdominal mass and 3 cm × 4 cm firm nodular mass in her left paramedian abdominal operative scar. Bilateral mammograms showed a dense background with an area of benign appearing microcalcification in the upper outer quadrant of her left breast (Fig. 1). This was away from the region of the palpable lump. Ultrasound showed a patchy, hypoechoic area measuring 30 mm × 45 mm in the lower outer quadrant of the left breast (Fig. 2). A core biopsy was then performed which showed the lesion to be benign spindle cell lesion in keeping with a fibromatosis of the breast. Immunohistochemistry was performed on the core biopsy specimen which was negative for AE1/3, MNF, S100, CD34. It was positive for SMA (smooth muscle actin), desmin and β-catenin. The specimen was negative for oestrogen, progesterone and androgen receptors. A skull X-ray was obtained which was normal.
Due to her breast pain and discomfort, she wished to have the left breast lump excised. Intraoperatively, it was found to be infiltrating the pectoralis major muscle and was excised in toto along with the infiltrated portion of the pectoralis muscle (Fig. 3). An intraoperative mammogram of the specimen was performed which did not demonstrate the lesion (Fig. 4). Her post operative period was uneventful. Histopathology of the specimen confirmed the findings of the core biopsy (Fig. 5). The lesion was shown to be a fibromatosis with no cellular atypia, all margins except the posterior margin were clear. The posterior margin showed infiltration of the tumour into the muscle fibres, following a discussion in our multi disciplinary team (MDT) meeting she has now been offered radiotherapy and NSAIDs to reduce her likelihood of a recurrence.
The emergence of our understanding of the systemic nature of Gardner's syndrome is well demonstrated in the protracted clinical history of this patient. She initially presented at the age of twenty with polyposis of the colon and had a subtotal colectomy, this was followed by recurrent intra-abdominal and abdominal wall desmoid tumours. More recently, apart from her breast lump she has developed polyps in the duodenum. This type of progressive multi-system involvement is classical of Gardner's syndrome.5
Desmoid tumours associated with Gardner's syndrome have been shown to have an alteration of the β-catenin pathway and over express β-catenin, as was seen in our patient.8 Fibromatoses associated with polyposis are usually noted in the colectomy scar, lesions may also be encountered in the small bowel mesentery, as dense intraabdominal adhesions, and very rarely in extra-abdominal sites.4,5
Our patient presented with mastalgia and a painful lump. Most reports in literature suggest otherwise, with the tumour being a painless, lump that mimics a carcinoma on clinical examination.1–3,10 Mammography typically show a high density, spiculated, stellate tumour without microcalcifications often indistinguishable from carcinoma.1,2,7 This was in contrast to the mammographic findings we noted in our patient, this lesion was not picked up by screening, preoperative and postoperative specimen mammograms.
On ultrasound scan, desmoid tumours are frequently poorly marginated, hypoechoic masses with a thick echogenic rim and posterior attenuation.3,7 Fine needle aspiration cytology or preferably core biopsy, although not entirely specific, may lead to a diagnosis of breast fibromatosis and is useful in planning a surgical approach to the lesion. The degree of cellularity can vary with fingerlike extensions extending at the periphery of the lesion into adjacent breast parenchyma.1,2,9 The histopathologic differential diagnosis can vary from benign reactive lesions such as a hyperproliferative scar, to a more sinister fibrosarcoma.9
Due to the unapparent extensions of these lesions into adjoining tissues, wide local excision is the recommended treatment. A recurrence rate ranging from 21 to 57% has been noted with surgical treatment alone.1–3,12 Margin status, large tumour size and young age have been associated with a higher incidence of recurrence.2,12 As breast fibromatosis do not demonstrate metastatic capabilities, axillary dissection is not performed. A routine quarterly clinical examination is advised for a minimum of three years as the majority of local recurrences manifest within this time frame.2,12,13
The high recurrence rate associated with surgical resection of extra-abdominal desmoid tumours has resulted in a number of adjuvant therapies being explored.2,12–15 Even though there is conflicting evidence in literature, radiation therapy is often employed to improve local control rates and has been shown in one systematic review to improve local control when used alone or in combination with surgery, when compared with surgery alone.12 Postoperative radiation therapy can improve the 10-year recurrence-free survival rate.14 The current options for pharmacological treatment of desmoid tumours range from NSAIDs to hormonal agents to cytotoxic therapy, but the mechanisms by which most of these agents affect desmoid tumours are not entirely clear. NSAIDs, most commonly Indomethacin and Sulindac, have been associated with partial responses or even complete resolution of desmoid tumours.2,13,15 Extramammary desmoid tumours are usually positive for oestrogen and progesterone receptors, and therefore a role for hormonal therapy has been proposed.11 Hormonal agents (Tamoxifen and Toremifene) have shown response rates of 30–50% over one year.16 Mammary desmoids especially those associated with polyposis syndromes are characteristically negative for hormone receptors as was observed in this case and hence our patient was not offered any hormonal therapy.11 An interesting study by Ishizuka et al. has shown Tamoxifen to be effective even in oestrogen receptor (ER) negative breast desmoid tumours, this may partly be explained by the fact that Tamoxifen induces the synthesis of transforming growth factor beta 1 (TGFβ1) by ER-negative fibroblasts, which can cause apoptosis and regression of the tumour.11 A variety of cytotoxic therapies have been used with no clear superiority of any one regimen.2
Desmoid tumour of the breast may present a difficulty in the diagnosis especially where imaging studies are not conclusive and suggest a more ominous diagnosis. A biopsy is always indicated as the definitive method to determine nature of the tumour. Management of these lesions is complex, the main problem being the high rates of recurrence. Wide surgical resection with clear margins is the most widely practiced technique with radiation, chemotherapy, or hormonal therapy being used to reduce recurrence rates.
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.
Mr. Ashwin Rammohan contributed to data collection, writing and Mr. Jeremy J. Wood contributed to writing, analysis and editing.