| Abstract|| |
Soft tissue neoplasms of breast thought to be derived from Myofibroblasts have been classified as myofibroblastomas. Myofibroblasts are spindle shaped mesenchymal cells derived from fibroblasts. These are rare neoplasms (more often seen in the male breast) and have same structural and immunohistochemical characteristics as those of solitary fibrous tumors. We present a case of an adult female presenting as firm breast lump diagnosed as myofibroblastoma and confirmed by diffuse positivity of CD34 immunohistochemical stain.
Keywords: Benign, mesenchymal tumors, myofibroblasts
|How to cite this article:|
Qureshi A, Kayani N. Myofibroblastoma of breast. Indian J Pathol Microbiol 2008;51:395-6
| Introduction|| |
Myofibroblastomas are rare benign mesenchymal tumors of breast.  These were commonly found in male breast but recently quiet a few have been reported in female breast as well. As these tumors share morphological and immunohistochemical features with solitary fibrous tumor,  some authors believe that these should be classified as solitary fibrous tumors. Myofibroblastomas are distinguished from spindled myoepithelial cells on the basis of their distributions as well as their immunohistochemical features.  Myofibroblastomas are positive for CD34 where as myoepithelial cells are immunoreactive far S-100 protein and cytokeratins. Nonpalpable myofibroblastomas been detected by mammography. , There is no attachment to skin. The broad differential diagnosis includes fibroepithelial lesions, smooth muscle tumors and myoepithelial proliferations.
| Case History|| |
We received a breast lump of a 40-year-old female. The specimen comprised of an un-oriented lumpectomy specimen measuring 4.5 × 4 × 3 cm. Attached ellipse of skin measured 3 × 1.0 cm. Serial sectioning revealed a firm, circumscribed tan-grey lobulated nodule measuring 2.8 × 2 × 2 cm [Figure 1]. Histological evaluation revealed bundles of slender, bipolar uniform spindle shaped cells arranged in clusters with intervening broad bands of hyalinized ropey collagen. Adipose tissue was seen trapped within these spindle cells [Figure 2]. No cellular atypia necrosis or increased mitotic activity was seen. These spindle cells were diffusely picture for CD34 [Figure 3] and were negative for cytokeratin AE1/A3 immunohistochemical stain. Sections from overlying skin were unremarkable. A diagnosis of myofibroblastoma of breast was made.
| Discussion|| |
Mammary neoplasms derived largely or entirely from Myofibroblasts are uncommon. Cases reported in the literature are mostly in men ranging from 41 to 85 years of age (median age 64 years); however, this lesion also occurs in women.  Radiologically, the tumors are homogenous lobulated and well circumscribed and they lack micro calcifications. , Magnetic resonance imaging revealed homogenous enhancement with internal septations. There is no attachment to overlying skin.
Grossly majority of the lesions are less than 4 cm. the excised mass is firm rubbery with a lobulated out surface. The cut surface consists of homogenous grey to pink whorled or lobulated tissue. Cystic degeneration, necrosis and hemorrhage have not been reported. Variable morphologic patterns have been described which include epithelioid, cellular collagenized and infiltrating variants. Rarely, the cells resemble well-differentiated smooth muscle cells. Majority of myofibroblastomas are immunoreactive for desmin, vimentin and CD34 and are negative for CK and weakly reactive to S-100. Myofibroblastomas must be considered in the differential diagnosis of spindle cell mammary tumors. It is important to distinguish them from phylloides tumors, spindle cell carcinomas and myoepithelial proliferations; which is possible by morphology and immunohistochemistry. Virtually all patients were managed by excision biopsy. No recurrences have been reported after a follow-up of 3-126 months. 
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Department of Pathology and Microbiology, Aga Khan University, Hospital, Stadium Road, P.O. Box 3500,Karachi, 74800
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]