ABSTRACT

INTRODUCTION:

Benign tumors are often seen in breast screening examinations. However, the differential diagnosis is not always simple because of radiological similarity between the different benign lesions.

CASE REPORT:

We present a rare case report of leiomyoma of the breast parenchyma in a 68-year-old asymptomatic patient. The mammographic and ultrasonographic findings were similar to those observed in benign lesions.

CONCLUSION:

The histopathological diagnosis requires careful differentiation from lesions that have smooth muscle proliferation, especially leiomyosarcoma. The most commonly performed treatment is resection of the lesion with free margins. Although breast leiomyoma is rare, it should be considered among the differential diagnoses for breast nodules of benign appearance. Resection with safety margins proved to be the only treatment needed.

KEYWORDS:
Breast; Ultrasonography; Leiomyoma; Breast neoplasms; Diagnosis

INTRODUCTION

Leiomyoma is considered to be the rarest non-epithelial tumor of the breast.¹1. Kaufman HL, Hirsch EF. Leiomyoma of the breast. J Surg Oncol. 1996;62(1):62-4. It occurs more frequently in the retroareolar region because of the greater amount of smooth muscle in this location.²2. Strader LA, Galan K,Tenofsky PL. Intraparenchymal leiomyoma of the male breast. Breast J. 2013;19(6):675-6.Its presence in the mammary parenchyma is extremely rare, with fewer than 30 cases reported so far in the literature.³3. Alawad AA. Multiple parenchymal leiomyomas of the breast in a Sudanese female. Breast Dis. 2014;34(4):165-7. The clinical, radiological and pathological characteristics do not differ markedly from those observed in the most frequent benign lesions. We report a case of leiomyoma in the breast parenchyma that was seen in our service and conducted a review of the literature, with special attention to radiological features that have been described so far.

CASE REPORT

A 68-year-old woman was seen at the Division of Mastology, Department of Gynecology of the Federal University of São Paulo (Universidade Federal de São Paulo, UNIFESP) with a non-palpable tumor that had been detected through screening mammography. The patient presented controlled hypertension and minor degenerative osteoarticular alterations. She reported having had three pregnancies and two deliveries, with thirty months of breastfeeding. She said that she did not have any other symptoms such as papillary flow or cutaneous lesions. She reported having had routine annual mammograms and that she had not had any previous surgery or biopsies. The mammogram performed two years earlier did not show any abnormalities. The physical examination was unremarkable, with no evidence of any palpable mass, skin changes or axillary lymphadenopathy

Imaging findings

Mammographic images showed an isodense circumscribed oval mass measuring 1.8 × 1.0 cm that was located at the junction of the upper quadrants of the left breast. Sonographic images of the left breast showed a hypoechoic homogenous oval mass measuring 1.4 × 0.7 cm that was horizontal and parallel to the skin. It had two lobulations and circumscribed margins, and was coincident with the location described through mammography (Figure 1). The lesion did not present any posterior acoustic shadow, hyperechoic halo or other associated abnormal features. The mass was classified as being in Breast Imaging-Reporting and Data System (BI-RADS) category 4.

Figure 1.
Sonographic findings in breast leiomyoma, demonstrating a hypoechoic oval mass that was predominantly circumscribed but sometimes showed microlobulated margins, and which was parallel to the breast skin. It was classified via ultrasonography in Breast Imaging-Reporting and Data System (BI-RADS) category 4.

Histopathological findings

An ultrasound-guided breast core biopsy with a 12-gauge needle was performed and five fragments were obtained. The pathological evaluation showed a mesenchymal neoplasm with muscle differentiation. The patient underwent surgical excision of the lesion. The histological findings revealed a circumscribed lesion with a pattern of fusiform proliferation and formation of interlaced bundles and fascicles (Figure 2). No cellular atypia, necrosis or mitotic figures was found. Immunohistochemical stains for CD34 and S100 were positive, and negative for desmin and smooth muscle actin. A diagnosis of smooth muscle tumor, and specifically mammary parenchyma leiomyoma, was established. There was no recurrence of the lesion after followup of 60 months.

Figure 2.
Histological sections revealing circumscribed appearance of the lesion, with proliferation of fusiform pattern and lack of atypical forms. Staining with hematoxylin and eosin (10 × and 40 x).

DISCUSSION

Even though Strong's first paper on breast leiomyoma was published in 1913, knowledge of the etiology of this condition remains uncertain.⁴4. Strong LW. Leiomyoma of the breast. Am J Obstet. 1913;68:53-5. It has been taken to originate from smoothmuscle angiomatous cells, given the “angiocentric” proliferation of smooth muscle that is observed. This theory is reinforced through the observation that blood vessels are present at locations showing defects or artefacts of histological fixation.⁵5. Diaz-Arias AA, Hurt MA, Loy TS, Seeger RM, Bickel JT. Leiomyoma of the breast. Hum Pathol. 1989;20(4):396-9.Current immunohistochemical findings rule out teratogenic origins. Uncertainty remains regarding theories of embryological displacement of smooth muscle cells of the areola, and regarding an origin from multipotent mesenchymal cells. These were proposed in the first half of the twentieth century by Melnick⁶6. Melnick PJ. Fibromyoma of the breast. Arch Pathol. 1932;14:794-8.and Shauder.⁷7. Schauder H. Über Leiomyome der Brustdrüse. Deutsche Zeitschrift für Chirurgie. 1927;205(1 ):58-68. Available from: http://link.springer.com/article/10.1007/BF02794721. Accessed in 2017 (Apr 26).
http://link.springer.com/article/10.1007...

Breast leiomyoma occurs predominantly in women, with only one case reported in a man.²2. Strader LA, Galan K,Tenofsky PL. Intraparenchymal leiomyoma of the male breast. Breast J. 2013;19(6):675-6. The age of highest incidence is between 40 and 60 years. It presents as an isolated tumor of slow growth, with similar characteristics to the most common benign tumors.⁸8. Leibowich RJ, Lenz G. Primary fibromyoma of the breast: Report of a case and review of the literature. American Journal of Cancer. 1940;38(1):73-5. Available from: http://cancerres.aacrjournals.org/content/amjcancer/38/1/73.full.pdf Accessed in 2017 (Apr 26).
http://cancerres.aacrjournals.org/conten... ^,99. Stein RJ. Fibroleiomyoma of the breast. Arch Pathol. 1943;33:72-4.^,1010. Craig JM. Leiomyoma of the female breast. Arch Pathol (Chic). 1947;44(3):314-7.The presence of pain was observed in only three cases, being more frequent in tumors of areolar location due to the contraction of neoplastic muscle cells.¹¹11. Ku J, Campbell C, Bennett I. Leiomyoma of the nipple. Breast J. 2006;12(4):377-80.

Physical examination usually reveals a mobile nodule with welldefined limits and fibroelastic consistency, although sometimes it has been reported to have hardened consistency.¹²12. Tamir G, Yampolsky I, Sandbank J. Parenchymal leiomyoma of the breast. Report of a case and clinicopathological review. Eur J Surg Oncol. 1995;21(1):88-9.^,1313. Nazário AC,Tanaka CI, de Lima GR, Gebrim LH, Kemp C. Leiomyoma of the breast. A case report. Sao Paulo Med J. 1995;113(5):992-4.^,1414. Heyer H, Ohlinger R, Schimming A, Schwesinger G, Grunwald S. Parenchymal leiomyoma of the breast--clinical, sonographic, mammographic and histological features. Ultraschall Med. 2006;27(1):55-8. Mammographic images have been described as showing an isodense or hyperdense oval mass, with outlines that are most often circumscribed (Table 1).¹1. Kaufman HL, Hirsch EF. Leiomyoma of the breast. J Surg Oncol. 1996;62(1):62-4.^,1313. Nazário AC,Tanaka CI, de Lima GR, Gebrim LH, Kemp C. Leiomyoma of the breast. A case report. Sao Paulo Med J. 1995;113(5):992-4.^,1515. Pourbagher A, Pourbagher MA, Bal N, Oguzkurt L, Ezer A. Leiomyoma of the breast parenchyma. AJR Am J Roentgenol. 2005;185(6):1595-7.^,1616. Minami S, Matsuo S, Azuma T, et al. Parenchymal leiomyoma of the breast: a case report with special reference to magnetic resonance imaging findings and an update review of literature. Breast Cancer. 2011;18(3):231-6.^,1717. Sidoni A, Lüthy L, Bellezza G, Consiglio M, Bucciarelli E. Leiomyoma of the breast: case report and review of the literature. Breast. 1999;8(5):289-90.^,1818. Son EJ, Oh KK, Kim EK, et al. Leiomyoma of the breast in a 50-year-old woman receiving tamoxifen. AJR Am J Roentgenol. 1998;171 (6):1684-6.^,1919. Ende L, Mercado C, Axelrod D, et al. Intraparenchymal leiomyoma of the breast: a case report and review of the literature. Ann Clin Lab Sci. 2007;37(3):268-73.^,2020. Lauwers G, de Roux S,Terzakis J. Leiomyoma of the breast. Arch Anat Cytol Pathol. 1990;38(3):108-10.^,2121. Shah SD, Gupta A, Roy S, Mukhopadhyay S. Intraparenchymal leiomyoma of the breast: a case report. Indian J Surg. 2013;75(Suppl 1):88-9. Microcalcifications relating to leiomyoma have never been described.¹⁵15. Pourbagher A, Pourbagher MA, Bal N, Oguzkurt L, Ezer A. Leiomyoma of the breast parenchyma. AJR Am J Roentgenol. 2005;185(6):1595-7.^,1616. Minami S, Matsuo S, Azuma T, et al. Parenchymal leiomyoma of the breast: a case report with special reference to magnetic resonance imaging findings and an update review of literature. Breast Cancer. 2011;18(3):231-6.^,2222. Manna P, Giuseppetti GM, Latini L, Baldassarre S, Antognoli S. [A case of leiomyoma of the breast]. Radiol Med. 1993;86(1-2):155-8.^,2323. Kotsuma Y, Wakasa K, Yayoi E, et al. A case of leiomyoma of the breast. Breast Cancer. 2001;8(2):166-9.

The effectiveness of mammography is limited in relation to lesions measuring less than 1.0 cm and breasts with predominant glands. Sonography frequently shows a hypoechoic mass with well-defined limits and oval shape.¹⁷17. Sidoni A, Lüthy L, Bellezza G, Consiglio M, Bucciarelli E. Leiomyoma of the breast: case report and review of the literature. Breast. 1999;8(5):289-90. Presence of lobulations has frequently been observed. Growth parallel to the skin has been observed in 100% of the cases. No well-defined posterior acoustic shadowing has been described.¹⁸18. Son EJ, Oh KK, Kim EK, et al. Leiomyoma of the breast in a 50-year-old woman receiving tamoxifen. AJR Am J Roentgenol. 1998;171 (6):1684-6.

Magnetic resonance imaging findings were first reported by Minami et al. They described a circumscribed oval nodule, with hypersignal in T1 and T2, and homogeneous enhancement after gadolinium infusion. They pointed out that presence of degeneration can influence the signal pattern in different sequences, as noted in leiomyoma in other regions of the body.¹⁶16. Minami S, Matsuo S, Azuma T, et al. Parenchymal leiomyoma of the breast: a case report with special reference to magnetic resonance imaging findings and an update review of literature. Breast Cancer. 2011;18(3):231-6.

The differential diagnosis should be done in relation to lesions that have smooth muscle proliferation in the absence of epithelial or ductal structures. In this context, the lesions that comprise the differential diagnosis are angioleiomyoma, fibroadenoma and malignant phyllodes tumor.²⁴24. Libcke JH. Leiomyoma of the breast. J Pathol. 1969;98(1):89-90.^,2525. Roncaroli F, Rossi R, Severi B, Martinelli GN, Eusebi V. Epithelioid leiomyoma of the breast with granular cell change: a case report. Hum Pathol. 1993;24(11):1260-3.^,2626. Magro G, Michal M, Bisceglia M. Benign spindle cell tumors of the mammary stroma: diagnostic criteria, classification, and histogenesis. Pathol Res Pract. 2001;197(7):453-66. Because mature adipose tissue is needed to identify cases of hamartoma, this lesion does not provide difficulties in the differential diagnosis.⁵5. Diaz-Arias AA, Hurt MA, Loy TS, Seeger RM, Bickel JT. Leiomyoma of the breast. Hum Pathol. 1989;20(4):396-9. In cases of lesions suggestive of leiomyoma, leiomyosarcoma is the main situation that needs to be ruled out.¹⁹19. Ende L, Mercado C, Axelrod D, et al. Intraparenchymal leiomyoma of the breast: a case report and review of the literature. Ann Clin Lab Sci. 2007;37(3):268-73.^,2727. Stafyla VK, Gauvin JM, Farley DR. A 53-year-old woman with a leiomyosarcoma of the breast. Curr Surg. 2004;61(6):572-5.

Presence of 2-16 mitotic figures per 10 high-power figures is the main feature for diagnosing leiomyosarcoma. According to Pourbagher, presence of 1-3 mitotic figures might be considered to represent an intermediate category because of the higher risk of local recurrence and, therefore, treatment that is more radical.¹⁵ Boscaino et al. reported local recurrence in two cases initially diagnosed as leiomyoma. Histological reevaluation of the lesions found presence of increased mitotic activity, and the lesions were reclassified as smooth-muscle neoplasms of undetermined prognosis.²⁸ In patients with a confirmed diagnosis of breast leiomyoma, no cases of local recurrence have been reported to date.¹¹11. Ku J, Campbell C, Bennett I. Leiomyoma of the nipple. Breast J. 2006;12(4):377-80.^,1212. Tamir G, Yampolsky I, Sandbank J. Parenchymal leiomyoma of the breast. Report of a case and clinicopathological review. Eur J Surg Oncol. 1995;21(1):88-9.^,1313. Nazário AC,Tanaka CI, de Lima GR, Gebrim LH, Kemp C. Leiomyoma of the breast. A case report. Sao Paulo Med J. 1995;113(5):992-4.^,1414. Heyer H, Ohlinger R, Schimming A, Schwesinger G, Grunwald S. Parenchymal leiomyoma of the breast--clinical, sonographic, mammographic and histological features. Ultraschall Med. 2006;27(1):55-8.^,1515. Pourbagher A, Pourbagher MA, Bal N, Oguzkurt L, Ezer A. Leiomyoma of the breast parenchyma. AJR Am J Roentgenol. 2005;185(6):1595-7.^,1616. Minami S, Matsuo S, Azuma T, et al. Parenchymal leiomyoma of the breast: a case report with special reference to magnetic resonance imaging findings and an update review of literature. Breast Cancer. 2011;18(3):231-6.^,1717. Sidoni A, Lüthy L, Bellezza G, Consiglio M, Bucciarelli E. Leiomyoma of the breast: case report and review of the literature. Breast. 1999;8(5):289-90.^,1818. Son EJ, Oh KK, Kim EK, et al. Leiomyoma of the breast in a 50-year-old woman receiving tamoxifen. AJR Am J Roentgenol. 1998;171 (6):1684-6.^,1919. Ende L, Mercado C, Axelrod D, et al. Intraparenchymal leiomyoma of the breast: a case report and review of the literature. Ann Clin Lab Sci. 2007;37(3):268-73.^,2222. Manna P, Giuseppetti GM, Latini L, Baldassarre S, Antognoli S. [A case of leiomyoma of the breast]. Radiol Med. 1993;86(1-2):155-8.^,2323. Kotsuma Y, Wakasa K, Yayoi E, et al. A case of leiomyoma of the breast. Breast Cancer. 2001;8(2):166-9.^,2424. Libcke JH. Leiomyoma of the breast. J Pathol. 1969;98(1):89-90.^,2525. Roncaroli F, Rossi R, Severi B, Martinelli GN, Eusebi V. Epithelioid leiomyoma of the breast with granular cell change: a case report. Hum Pathol. 1993;24(11):1260-3.^,2626. Magro G, Michal M, Bisceglia M. Benign spindle cell tumors of the mammary stroma: diagnostic criteria, classification, and histogenesis. Pathol Res Pract. 2001;197(7):453-66.^,2727. Stafyla VK, Gauvin JM, Farley DR. A 53-year-old woman with a leiomyosarcoma of the breast. Curr Surg. 2004;61(6):572-5.

We reviewed the literature in MEDLINE and Lilacs using the English keywords “leiomyoma”, “fibroid tumors”, “benign tumor”, “benign neoplasms”, “breast tumor”, “breast neoplasms” and “ultrasonography”. We found 30 case reports that described patients with leiomyoma in the breast parenchyma (Table 2).

In reviewing treatments that have been implemented, a wide range of interventions can be identified, from lumpectomy to radical mastectomy (Table 3).¹1. Kaufman HL, Hirsch EF. Leiomyoma of the breast. J Surg Oncol. 1996;62(1):62-4.^,22. Strader LA, Galan K,Tenofsky PL. Intraparenchymal leiomyoma of the male breast. Breast J. 2013;19(6):675-6.^,44. Strong LW. Leiomyoma of the breast. Am J Obstet. 1913;68:53-5.^,55. Diaz-Arias AA, Hurt MA, Loy TS, Seeger RM, Bickel JT. Leiomyoma of the breast. Hum Pathol. 1989;20(4):396-9.^,66. Melnick PJ. Fibromyoma of the breast. Arch Pathol. 1932;14:794-8.^,77. Schauder H. Über Leiomyome der Brustdrüse. Deutsche Zeitschrift für Chirurgie. 1927;205(1 ):58-68. Available from: http://link.springer.com/article/10.1007/BF02794721. Accessed in 2017 (Apr 26).
http://link.springer.com/article/10.1007... ^,88. Leibowich RJ, Lenz G. Primary fibromyoma of the breast: Report of a case and review of the literature. American Journal of Cancer. 1940;38(1):73-5. Available from: http://cancerres.aacrjournals.org/content/amjcancer/38/1/73.full.pdf Accessed in 2017 (Apr 26).
http://cancerres.aacrjournals.org/conten... ^,99. Stein RJ. Fibroleiomyoma of the breast. Arch Pathol. 1943;33:72-4.^,1010. Craig JM. Leiomyoma of the female breast. Arch Pathol (Chic). 1947;44(3):314-7.^,1313. Nazário AC,Tanaka CI, de Lima GR, Gebrim LH, Kemp C. Leiomyoma of the breast. A case report. Sao Paulo Med J. 1995;113(5):992-4.^,1515. Pourbagher A, Pourbagher MA, Bal N, Oguzkurt L, Ezer A. Leiomyoma of the breast parenchyma. AJR Am J Roentgenol. 2005;185(6):1595-7.^,1616. Minami S, Matsuo S, Azuma T, et al. Parenchymal leiomyoma of the breast: a case report with special reference to magnetic resonance imaging findings and an update review of literature. Breast Cancer. 2011;18(3):231-6.^,1717. Sidoni A, Lüthy L, Bellezza G, Consiglio M, Bucciarelli E. Leiomyoma of the breast: case report and review of the literature. Breast. 1999;8(5):289-90.^,1818. Son EJ, Oh KK, Kim EK, et al. Leiomyoma of the breast in a 50-year-old woman receiving tamoxifen. AJR Am J Roentgenol. 1998;171 (6):1684-6.^,1919. Ende L, Mercado C, Axelrod D, et al. Intraparenchymal leiomyoma of the breast: a case report and review of the literature. Ann Clin Lab Sci. 2007;37(3):268-73.^,2020. Lauwers G, de Roux S,Terzakis J. Leiomyoma of the breast. Arch Anat Cytol Pathol. 1990;38(3):108-10.^,2121. Shah SD, Gupta A, Roy S, Mukhopadhyay S. Intraparenchymal leiomyoma of the breast: a case report. Indian J Surg. 2013;75(Suppl 1):88-9.^,2424. Libcke JH. Leiomyoma of the breast. J Pathol. 1969;98(1):89-90.^,2929. Haagensen CD. Nonepithelial neoplasms of the breast. In: Haagensen CD (editor). Diseases of the Breast. 2nd ed. Saunders: Philadelphia; 1971. p. 292-325. However, since the report by Lauwers in 1990, the standard treatment has been resection with free margins.²⁰20. Lauwers G, de Roux S,Terzakis J. Leiomyoma of the breast. Arch Anat Cytol Pathol. 1990;38(3):108-10.^,2121. Shah SD, Gupta A, Roy S, Mukhopadhyay S. Intraparenchymal leiomyoma of the breast: a case report. Indian J Surg. 2013;75(Suppl 1):88-9.

CONCLUSION

In conclusion, it can be said that leiomyoma in mammary tissue is an extremely rare condition. The clinical presentation does not differ from that observed in the most common benign tumors of the breast. The radiological findings are characteristically benign, which helps rule out the hypothesis of cancer. In histopathologi-cal evaluations, it is important to pay attention to the differential diagnosis of leiomyosarcoma. The standard recommended treatment is local resection with free margins. In this situation, the risk of local recurrence is practically zero.

REFERENCES

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