Mammary-type myofibroblastoma

Mammary-type myofibroblastoma
Other namesMammary and extramammary myofibroblastoma
Micrograph of mammary myofibroblastoma. H&E stain.
SpecialtyOncology, Pathology

Mammary-type myofibroblastoma (MFB),[1] also named mammary and extramammary myofibroblastoma,[2] was first termed myofibrolastoma of the breast,[3] or, more simply, either mammary myofibroblastoma (MMFB) or just myofibroblastoma.[4][5] The change in this terminology occurred because the initial 1987 study[3] and many subsequent studies[1] found this tumor only in breast tissue. However, a 2001 study[6] followed by numerous reports[1] found tumors with the microscopic histopathology and other key features of mammary MFB in a wide range of organs and tissues.[1] Further complicating the issue, early studies on MFB classified it as one of various types of spindle cell tumors that, except for MFB, were ill-defined. These other tumors, which have often been named interchangeably in different reports, are: myelofibroblastoma, benign spindle cell tumor, fibroma, spindle cell lipoma, myogenic stromal tumor, and solitary stromal tumor. Finally, studies suggest that spindle cell lipoma and cellular angiofibroma are variants of MFB.[5][7] Here, the latter two tumors are tentatively classified as MFB variants but otherwise MFB is described as it is more strictly defined in most recent publications.[1] The World Health Organization in 2020 classified mammary type myofibroblastoma tumors and myofibroblastoma tumors (i.e. extramammary myofibroblastic tumors) as separate tumor forms within the category of fibroblastic and myofibroblastic tumors.[8]

Mammary MFB likely represents less than 1% of all breast tumors.[9] Extramammary MFB, however, has in recent studies been found to occur far more frequently than mammary MFB: a study of 143 patients reported that extramammary MFB outnumbered mammary MFB 10 to 1.[5] Hence, the overall disease may be more common than previously considered. Extramammary MFB occurs about equally in males and females of both sexes and has a broad age distribution that includes children. Mammary MFB likewise occurs about equally in both sexes but has a decided predominance in middle-aged and older adults.[9]

MFB are completely benign tumors, i.e. they do not metastasize and when surgically removed rarely recur.[1] Microscopically, they consist of neoplastic spindle cells,[10] i.e. cells that are longer than wide, have a morphology somewhere between fibroblasts and myofibroblasts, have similarly appearing counterparts in normal tissues, and in normal tissues are usually identified as fibroblasts.[9] The neoplastic cells commonly: 1) have acquired a gene chromosome abnormality in which a small part of chromosome 13 is deleted;[9] 2) fail to express the retinoblastoma protein (pRb) due to this deletion;[11] and 3) contain key tumor marker proteins.[9] A tumor with this characteristic microscopic appearance, 13q14 deletion, loss of pRb, and presence of marker proteins strongly indicate that it is a MFB[7] and, importantly, distinguishes it from other more aggressive tumors that it may otherwise resemble and be diagnosed as.[12]

  1. ^ a b c d e f Wickre M, Valencia E, Solanki M, Glazebrook K (April 2021). "Mammary and extramammary myofibroblastoma: multimodality imaging features with clinicopathologic correlation, management and outcomes in a series of 23 patients". The British Journal of Radiology. 94 (1120): 20201019. doi:10.1259/bjr.20201019. PMC 8010555. PMID 33332985.
  2. ^ Den Hartog T, Ness C, Strand D, Aasen G (August 2020). "Mammary-type Myofibroblastoma of the Pre-sacral Space: A Rare Neoplasm". South Dakota Medicine. 73 (8): 342–345. PMID 32809291.
  3. ^ a b Wargotz ES, Weiss SW, Norris HJ (July 1987). "Myofibroblastoma of the breast. Sixteen cases of a distinctive benign mesenchymal tumor". The American Journal of Surgical Pathology. 11 (7): 493–502. doi:10.1097/00000478-198707000-00001. PMID 3037930. S2CID 43691738.
  4. ^ Allahverdi TD, Allahverdi E (April 2017). "Myofibroblastoma". The Journal of Breast Health. 13 (2): 100–102. doi:10.5152/tjbh.2017.3232. PMC 5381673. PMID 31244537.
  5. ^ a b c Howitt BE, Fletcher CD (March 2016). "Mammary-type Myofibroblastoma: Clinicopathologic Characterization in a Series of 143 Cases". The American Journal of Surgical Pathology. 40 (3): 361–7. doi:10.1097/PAS.0000000000000540. PMID 26523539. S2CID 45911598.
  6. ^ McMenamin ME, Fletcher CD (August 2001). "Mammary-type myofibroblastoma of soft tissue: a tumor closely related to spindle cell lipoma". The American Journal of Surgical Pathology. 25 (8): 1022–9. doi:10.1097/00000478-200108000-00006. PMID 11474286. S2CID 31522598.
  7. ^ a b Magro G, Angelico G, Righi A, Benini S, Salvatorelli L, Palazzo J (November 2018). "Utility of STAT6 and 13q14 deletion in the classification of the benign spindle cell stromal tumors of the breast". Human Pathology. 81: 55–64. doi:10.1016/j.humpath.2018.06.015. PMID 29940288. S2CID 49410824.
  8. ^ Sbaraglia M, Bellan E, Dei Tos AP (April 2021). "The 2020 WHO Classification of Soft Tissue Tumours: news and perspectives". Pathologica. 113 (2): 70–84. doi:10.32074/1591-951X-213. PMC 8167394. PMID 33179614.
  9. ^ a b c d e Scardina L, Franceschini G, Biondi E, Di Leone A, Sanchez AM, D'Archi S, Mason EJ, Angelico G, Santoro A, Mulè A, Masetti R (April 2021). "Myofibroblastoma of the breast: two case reports and literature review". Journal of Surgical Case Reports. 2021 (4): rjab133. doi:10.1093/jscr/rjab133. PMC 8062129. PMID 33927867.
  10. ^ "Search results". www.google.com. [better source needed]
  11. ^ Krings G, McIntire P, Shin SJ (September 2017). "Myofibroblastic, fibroblastic and myoid lesions of the breast". Seminars in Diagnostic Pathology. 34 (5): 427–437. doi:10.1053/j.semdp.2017.05.010. PMID 28751104.
  12. ^ Yan M, Bomeisl P, Gilmore H, Sieck L, Kuchta Z, Harbhajanka A (October 2020). "Clinicopathological and radiological characterization of myofibroblastoma of breast: A single institutional case review". Annals of Diagnostic Pathology. 48: 151591. doi:10.1016/j.anndiagpath.2020.151591. PMID 32829069. S2CID 221278334.