Myxoid Myofibroblastoma of the Breast With Atypical Cells

Abstract

The differential diagnosis of myxoid lesions in the breast is broad and includes both benign and malignant entities. Assessment is particularly challenging on core biopsy specimens. Myofibroblastoma, initially thought to be more common in the adult male breast, is being recognized with increasing frequency in the female breast. The wider anatomic distribution of mammary-type myofibroblastoma has also become known, and many new morphological variants have been described. Though focal myxoid stroma may be noted in myofibroblastomas and occasional myofibroblastomas may contain atypical cells, there have been only 3 reports in the literature of myofibroblastomas with exclusive or predominantly myxoid stroma, and 2 of these contained atypical cells. We report another case of mammary myxoid myofibroblastoma with atypical cells in a 40-year-old woman and discuss the differential diagnoses of myxoid lesions in the breast.

Mammary Myofibroblastoma in a Male: A Case Report and Review of the Literature

“…Extramammary myofibroblastoma was first described in 2001 by McMenamin and Fletcher [ 9 ]. Although initially described and thought to be more prevalent in males, MFB affects females with a similar incidence, probably due to increased mammographic screening [ 1 , 10 , 11 ]. Tumors may be detected earlier in women due to routine mammary screening, whereas in men MFB usually presents as a painless palpable mass [ 1 ].…”

“…In one case, a transgender patient developed an estrogen receptor positive MFB after receiving estrogen therapy for 13 months [ 17 ]. MFB also may be misdiagnosed as other benign or malignant breast diseases [ 1 ], particularly because clinical and radiological evidence may be suggestive of fibroadenoma [ 10 , 11 ]. Clinical presentation is characterized by a solid, solitary, slow-growing, mobile, well-circumscribed, and painless palpable mass that is firm to solid [ 3 , 10 , 13 , 18 ].…”

Intramammary Angiomatoid Fibrous Histiocytoma, a Rare EWSR1 Rearranged Mesenchymal Neoplasm in a Previously Unreported Anatomic Location with Review of the Cleveland Clinic Experience

“…Of particular interest to practitioners of breast pathology, mammary-type myofibroblastomas are benign mesenchymal neoplasms comprised of sheets of myofibroblasts, and these tumors are often immunoreactive with desmin [11, 12]. Occasional examples of myofibroblastoma have also been reported to have myxoid features and cellular pleomorphism, as can be seen in some examples of AFH [13]. Importantly, myofibroblastomas lack a lymphoid cuff and often contain intrinsic islands of adipose tissue.…”

Myofibroblastoma of the Male Breast: a Typical Case Report and Narrative Review

“…Another variants are leiomyomatous MFB, in which cells with smooth muscle cell differentiation with cigar-shaped nuclei (myoid) are present and H-caldesmon staining can be positive [27,28]; and myxoid MFB, in which there are diffuse myxoid changes [14,29,30]. This latter goes in differential diagnosis with other myxoid neoplasms, such as like low grade fibromxyoid sarcoma [31].…”