Fibromatosis de mama: una lesión simuladora de cáncer / Breast fibromatosis: a lesion mimicking cancer

BACKGROUND: Breast fibromatosis (BF) is a rare benign pathological entity. Its etiology is unknown, but it has been associated with surgical trauma and certain genetic disorders. CLINICAL CASES: Case 1. The patient was a 17-year-old female with a 20 x 15 cm firm and fixed mass in the right breast. A core-needle biopsy was taken with a pathology report of a phyllodes tumor. Mammography revealed a well-differentiated lesion with no evidence of muscle invasion. The patient underwent wide surgical resection with thoracotomy and chest wall resection of the affected ribs. Pathology reported a 19 x 18 x 9 cm BF with a positive surgical margin. Oral colchicine was administered and at 3 months of follow-up the patient is disease free. CASE 2. The patient was a 49-year-old female with a 7 x 5 cm solid right breast mass located at the medial-upper quadrant and fixed to the pectoralis major muscle. Mammography and magnetic resonance imaging revealed a mass infiltrating thoracic muscles. Wide surgical resection was performed with immediate latissimus dorsi reconstruction. Pathology report showed a BF with muscle invasion. At 3 months postsurgery, the patient is disease free. CONCLUSIONS: BF is a rare entity with a locally aggressive behavior. The infiltrative nature of this disease is associated with a tendency to recur locally. Its clinical and imaging features can mimic breast cancer. Differential diagnosis should be made before attempting treatment. The standard therapeutic modality is wide surgical resection, and radiotherapy is reserved for some cases with positive surgical margins.

Clasificación molecular del cáncer de mama / Molecular classification of breast cancer

Breast cancer is classified based on clinical stage, cellular morphology and immunohistochemical analysis. More precise prognostic factors are necessary to aid with therapeutic decisions. Breast cancer subtypes that differ in their genetic expression and prognosis have been determined using cDNA microarrays. These findings confirm the differences between the phenotypes and provide new knowledge about the biology of breast cancer. Based on the presence or absence of expression of the estrogen receptor (ER), breast cancer is divided in two groups: ER+ and ER-. Genetic expression profile has identified two subtypes of the ER+ tumors: luminal A and luminal B. ER- tumors also include two subtypes, the HER2+ and the basal type. These subtypes differ in their biology and both demonstrate short disease-free periods after treatment and poorer outcome. This classification has shown the relationship between cDNA microarrays and clinical outcome of these tumors. This classification is proposed as a method of identifying those patients who will demonstrate better results with the different adjuvant modalities.