Myofibroblastoma of the breast: Report of a case

Abstract

We report herein the case of a 36-year-old woman in whom a breast mass was diagnosed histologically and immunohistochemically as myofibroblastoma (MFB). The patient initially presented with a breast mass measuring 1.0 x 1.5 cm which was demonstrated by mammography as a well-circumscribed, round tumor with two coarse calcifications. On ultrasonography, the tumor showed slight shadowy internal echoes. Histological examination of an excisional biopsy specimen demonstrated a tumor consisting of spindle-shaped cells and broad bands of hyalinized collagen with cartilaginous and osseous components, but no epithelial components were observed. Immunohistochemically, the tumor cells were diffusely positive for alpha smooth muscle actin, and a diagnosis of MFB was made. A wide excision of the breast was performed as a secondary procedure, and the patient is well and free from recurrence 1 year after her operation. We present this case to stress the need for breast surgeons to be aware of the existence of MFB when considering the differential diagnosis of stromal lesions of the breast to avoid performing unnecessarily extensive procedures.

Myofibroblastoma of the breast with diverse histological features

“…Only two previously reported cases of myofibroblastoma [7,18], and case 1 of the present report, contained foci of cartilage. Other authors [15] have termed a similar case "mesenchymoma".…”

Lipomatous myofibroblastoma: a potential diagnostic pitfall in the spectrum of the spindle cell lesions of the breast

“…The myofibroblastic differentiation observed in MFB is explained if we assume that the mammary stromal cell is capable of altering its phenotype along different mesenchymal lines of differentiation. This is demonstrated by the variable coexistence of fibroblasts, myofibroblasts, mature smooth muscle cells, adipocytes and even occasional foci of mature cartilaginous and osseous tissues in the same case of MFB of breast [2,8,9,11,22,28,29,33]. Moreover, a similar multipotential differentiation of the mammary stroma is a well known occurrence in several breast pathologic conditions such as fibroadenoma with myofibroblastic [24] or leiomyomatous component [22], phyllodes tumour, hamartoma and so-called benign mesenchymoma [22].…”

Spindle cell lipoma-like tumor, solitary fibrous tumor and myofibroblastoma of the breast: a clinico-pathological analysis of 13 cases in favor of a unifying histogenetic concept

“…These cells are considered uncommitted stromal cells and, as such, are endowed with plasticity [42,48,60,67] to undergo multilineage proliferation along different pathways leading to heterogeneous pathological conditions such as SFT and SCL of soft tissues [60], and fibroadenomas, phylloides tumors and pseudoangiomatous hyperplasia in the breast [48]. Another speculative observation suggesting the role of the mammary stroma in tumorigenesis of BSST as a whole is given by the evidence that both fibroblastic and myofibroblastic tumors may contain a variable admixture of two or three lines of differentiation within the same neoplasm such as fibroblastic plus adipocytic in SCL/SCL-like tumor [39,42,65], and SFT [24,44,50,61] or fibroblastic plus myofibroblastic (in most cases of MFBs), myofibroblastic plus adipocytic [43] and, as reported elsewhere, myofibroblastic plus smooth muscle [20,64] or cartilaginous [20,33,34,68] or osseous [33] in rare cases of MFB. This is in accordance with the well-known multidirectional differentiation ability of the mammary stromal cells that may undergo changes in their phenotype in several other breast benign pathological conditions, typical examples of which include fibroadenoma with leiomyomatous component [23,64], phylloides tumors with fat, bone, cartilage or even skeletal muscle metaplasia [54,63], hamartomas with adipocytic, smooth muscle, and chondroid stromal components [15,38,54], and some breast lesions labeled as "mesenchymoma" in which even three lines of differentiation (e.g., myo-chondro-lipoma) can be documented [4,32].…”