Rare case of primary leiomyosarcoma of the breast treated with wide local excision and planned cosmetic breast reduction surgery

Abstract

Primary leiomyosarcoma of the breast is an extremely rare neoplasm accounting for less than 0.0006% of all breast malignancies, with fewer than 80 cases reported in the literature to date. Here, we present a case of leiomyosarcoma of the breast in a 61-year-old woman without traditional risk factors. This case was treated with lumpectomy requiring wide margins due to the high rate of local recurrence. A planned breast reduction surgery was deemed adequate postlumpectomy therapy to prevent cancer recurrence, negating the need for chemotherapy or radiation therapy. To our knowledge, this is the first case in which cosmetic breast reduction surgery will be used as postlumpectomy cancer recurrence risk mitigation for primary leiomyosarcoma of the breast. Patients with this malignancy have a relatively poor prognosis compared with other breast cancer types, with a 5-year disease-free survival of 33%–52%. As such, frequent follow-up and monitoring for postresection recurrence is essential.

Background

Sarcomas can occur anywhere in the body, but sarcomas of the breast are very rare. One study found that primary breast sarcomas account for less than 0.0006% of all breast malignancies.¹ Primary leiomyosarcoma of the breast, a malignant tumour of smooth muscle cells, accounts for approximately 5%–10% of all breast sarcomas, making it an extremely rare condition with fewer than 80 cases reported in the literature to date.² Here, we present a case of leiomyosarcoma of the breast that did not present with established risk criteria. The patient will not be treated with postlumpectomy chemotherapy or radiation therapy, but rather, with a planned cosmetic breast reduction surgery to achieve wider margins.

Case presentation

A 61-year-old woman with a history of morbid obesity, hypertension and osteoarthritis presented to the breast clinic for evaluation following a positive screening mammogram prior to planned breast reduction surgery for back and shoulder pain. Mammography revealed a suspicious 1.6 cm mass in the upper outer quadrant of the right breast. The patient had a history of a benign right breast mass discovered on screening mammogram 3 years prior but had not returned for additional imaging studies until her presurgical consultation for an elective breast reduction (figure 1). The patient appeared in a good state of health. She denied constitutional symptoms, fatigue, weight loss, palpable breast masses, nipple discharge, mastodynia, breast skin changes or arm swelling. She was a former 40 pack-year smoker, who had quit 5 years prior to presentation, without a family history of breast cancer, ovarian cancer or other neoplasms. Her obstetric history included gravity 5 parity 3, menarche at 14, first parity at 20 and menopause at 53. Due to the patient’s age and the suspicious mammographic findings, further investigation was warranted.

Figure 1.

Prereduction surgery breast photographs.

Investigations

Diagnostic mammogram revealed an isodense, ovoid mass with irregular margins in the right breast at the 11 o’clock position, without microcalcifications or right axillary lymphadenopathy. Confirmatory focused ultrasound showed an irregular hypoechoic nodule without internal vascularity that measured 1.5×1.1 x 1.6 cm (figure 2).

Figure 2.

Ultrasound image showing a well-circumscribed anechoic lesion (outlined by “+” symbols above) with scant internal echoes and mildly irregular borders measuring approximately 1.5×1.1x1.6 cm in the subcutaneous tissue of the right breast.

Pathological assessment of ultrasound-guided core needle biopsy of the mass was significant for spindle cells with mild to moderate atypia, staining diffusely positive for actin, focally positive for Cam 5.2 keratins and negative for caldesmon, Ae1 and Ae3 keratins (figure 3). Extensive hyalinisation and focal necrosis were also noted and significant.

Figure 3.

Pathology of biopsy samples shown: (A) H&E stain showing spindle cell architecture at ×100 magnification. (B) H&E stain showing mild to moderate atypia of the spindle cells at ×200 magnification. (C) Immunohistochemical stain showing diffuse positivity for actin (brown dye) at ×100 magnification. (D) Immunohistochemical stain showing focal positivity for Cam 5.2 keratins (brown dye).

Differential diagnosis

Following biopsy of the mass, the differential diagnosis was limited to leiomyosarcoma, a sarcomatoid carcinoma or periductal sarcoma (a variant of a phyllodes tumour) with pathology favouring leiomyosarcoma, withholding definitive diagnosis until excision of the mass.

Treatment

The patient underwent a wire-guided wide local excision with 2 cm margins revealing a 2.5 cm leiomyosarcoma on preliminary pathology. The final pathology report showed a 2.5×1.6x1.6 cm well-circumscribed mass containing the localisation wire with only the lateral and medial margins measuring over 2 cm in width—the rest were 1.5 cm. All margins were negative. Due to the rarity of the finding, the sample was sent to the Mayo Clinic for independent interpretation, confirming the diagnosis. Since the surgical margins were not wide enough to meet recommendations for this type of tumour, re-excision of the tumour bed was performed with additional anterior, posterior and inferior margins, revealing no residual leiomyosarcoma.

Following a multidisciplinary tumour board discussion and subsequent patient consultation, the patient was recommended to consider radiation therapy. She declined radiation because of her plan to proceed with breast reduction. It was determined that the removal of additional breast tissue would further improve margin width and potentially reduce cancer recurrence risk. The patient was scheduled for surgery; however, due to the COVID-19 pandemic, the operation was delayed. The surgery was postponed a second time when the patient tested positive for SARS-CoV-2, and the surgery date is pending at the time of this writing.

Outcome and follow-up

Metastatic workup including positron emission and CT scans were unremarkable, and the breast lesion was identified as the primary tumour. The tumour was determined to be stage T1A with high-grade differentiation. After discussion with the patient and multidisciplinary tumour board, radiation was recommended, however the patient declined due to her plan for breast reduction surgery. The patient is currently disease free 6 months postlumpectomy (figure 4). She will continue visits at 6-month intervals for follow-up examination, mammogram, and CT scan of the chest. She plans to have breast reduction surgery within the next 2 months. This regimen will continue for 7 years, at which time she will transition to annual screenings indefinitely.

Figure 4.

A 6-month postoperative CT scan of the chest showing a right chest wall subcutaneous homogeneous mass demonstrating soft tissue density measuring approximately 8.3×5.2 cm with linear projections at the periphery suggestive of postoperative fibrosis.

Discussion

We present a rare case of primary leiomyosarcoma of the breast in a 61-year-old woman. Leiomyosarcomas of the breast occur most commonly in postmenopausal women. Risk factors for the development of sarcomas include previous radiation, chronic lymphoedema, vinyl chloride exposure and Epstein-Barr virus infection in the setting of severe immunosuppression—none of which were present in our patient.³ These tumours present as an incidental mass on physical examination or screening mammography, as in our patient’s case, and are often initially mistaken for other benign or malignant breast pathologies due to their lack of characteristic imaging features. Definitive diagnosis relies on core needle biopsy or excisional biopsy with histopathological analysis. Histologically, leiomyosarcomas are characterised by spindle cell bundles with pleomorphic, hyperchromatic elongated nuclei and eosinophilic cytoplasm with grading determined by the degree of atypia, mitotic activity, cellularity and nuclear pleomorphism. Immunohistochemical stains show positivity to smooth muscle actin, desmin and vimentin.^{1 2}

Leiomyosarcomas of the breast are thought to originate from smooth muscle cells of blood vessels, nipple or malignant transformation from a leiomyoma. The primary route of dissemination of leiomyosarcoma, like all sarcomas, is haematological and local lymph node involvement is rare. At present, there are insufficient treatment guidelines for breast leiomyosarcoma, likely due to the rarity of the disease in this location. Therefore, sentinel lymph node biopsy is occasionally performed, despite the risk of lymphoedema and the haematogenous route of dissemination of most sarcomas.² The prognosis for breast leiomyosarcoma is poor relative to other breast cancer types, with a 5-year overall survival rate of 50%–66% and 5-year disease-free survival of 33%–52%.³ Metastatic disease occurs in 25% of patients and most often presents in the lungs or bones and may occur years after the initial resection.^{1 2} According to the literature, metastatic disease has been discovered up to 20 years after primary resection. Therefore, it is essential for patients to have regular follow-up examinations. Physicians should have a high index of suspicion for disease recurrence in any patient with a history of breast leiomyosarcoma.⁴

Management of early-stage leiomyosarcoma is surgical, with mastectomy or local excision depending on the tumour size. Unfortunately, leiomyosarcomas tend to recur locally and therefore require larger tumour margins (2 cm for breast-conservative treatment, 3 cm preferred) than recommended for ductal carcinoma (2 mm).^{2 5 6} Some cases of more advanced disease have been treated adjunctly with chemotherapy or radiation therapy. Postlumpectomy radiation therapy has shown improvement in disease-free survival in a limited sample size. While it has been postulated that chemotherapy may be efficacious in metastatic disease, this benefit is unclear.^{2 3 5} A single case report found a positive response after dual treatment with salvage hyperthermia and pazopanib (an oral, multitargeted tyrosine kinase inhibitor), which indicates that this may be a therapeutic option in patients who have failed other treatments.⁷ Postoperative radiation therapy is a well-established treatment for local recurrence of leiomyosarcoma at different body sites when wide local excision is not possible. Therefore, this may be a reasonable approach to leiomyosarcoma of the breast as well.⁵ To our knowledge, this is the first reported case in which breast reduction surgery is included for wider margins as postlumpectomy cancer recurrence risk mitigation.

Learning points.

• Primary leiomyosarcoma of the breast is an extremely rare neoplasm with high rates of local recurrence.

• Localised leiomyosarcoma of the breast requires a minimum of 2 cm surgical margins for breast-conservation therapy, with 3 cm margins preferred. In this case, a planned breast reduction surgery was used to achieve margins wider than 3 cm.

• Close follow-up with a high index of suspicion for recurrence is recommended for any patient with a history of leiomyosarcoma of the breast.