Benign spindle cell breast tumor

Abstract

A distinctive, benign, spindle cell tumor of the breast is described. Three patients were men, the fourth a woman. Histologically, each tumor displayed islands of spindle or stellate cells embedded in a collagenous matrix. Within the female breast, the lesion was within the stroma, displacing but not including the epithelial elements. Ultrastructural study of two tumors revealed diverse populations composed of fibroblasts, myofibroblasts, smooth muscle cells, and undifferentiated mesenchymal cells. The relationship of these tumors to spindle cell lipomas is discussed. The lesions have all been clinically benign, and their recognition as such is important. Cancer 48:1615-1622, 1981. HIS REPORT will document a distinctive type of T breast tumor. The lesion is histologically characteristic and is remarkable in that in three of the four cases presented, the patients were men (Table 1). Case Reports Case I The patient, a 46-year-old man, presented with a five-week history of a swelling in the right breast. He had a firm 2 x 3 cm nodule 2 cm below the right nipple. The mass was excised. The histologic features are illustrated in Figures 1 and 2. Aggregates of spindle shaped or stellate cells were embedded in a dense collagenous matrix. Nuclei stained darkly and were conspicuous. While the nuclei vaned somewhat in size and shape, pleomorphism was not pronounced. Mitoses were not seen. Cytoplasm was generally scanty although a few plump cells displayed more liberal amounts. Cell margins were often ill defined, especially where the cells were crowded together. Fine collagen fibrils were visible within the cell groups. A few mature fat cells were scattered throughout the lesion. The patient was last seen by the surgeon one year after the

Solitary fibrous tumour (myofibroblastoma) of the breast

“…All these features appear to be consistent with those of the breast lesions reported by Toker et al [16] as benign spindle cell tumour and by Wargotz et al [18] as myofibroblastoma. These tumours have to be distinguished from other benign lesions such as leiomyoma [5] and fibromatosis [17], and from malignant tumours (stromal sarcoma and sarcomatoid carcinomas) [7,13].…”

“…Toker et al [16] described two cases of a mammary stromal tumour constituted by a proliferation of spindle cells which they termed benign spindle cell tumour of the breast. More recently, Wargotz et al [18] reported a large series of this same entity which they renamed myofibroblastoma on the basis of the ultrastructural findings.…”

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

“…Tumors with similar features had been reported in the literature with different names, frequently used interchangeably, such as "benign spindle cell tumor" [7,65], "fibroma" [9], "spindle cell lipoma" [49,58], "solitary fibrous tumor" [12,31], "myofibroblastoma" [68], "myogenic stromal tumor", or "unusual variant of leiomyoma" [16,17]. The unifying morphological criterion of all these lesions is a well-circumscribed proliferation of blandlooking spindly to oval-epithelioid cells, haphazardly arranged or forming short fascicles and/or cellular clusters, and variably admixed with thick or less frequently thin collagen bands.…”

“…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].…”

Extramammary myofibroblastoma is genetically related to spindle cell lipoma

“…Mammary myofibroblastoma is a rare mesenchymal tumor arising in breast soft tissue [12,13]. Extramammary locations have been described in recent years, and the most common site is the inguinal/groin area, with an apparent predilection for the embryonic milk-line that extends from the axilla to the medial groin [9].…”