title: Comparison of Myofibroblasts Between Solid/Multicystic Ameloblastoma and Unicystic Ameloblastoma: An Immunohistochemical Analysis.
abstract: BACKGROUND
  Microenvironment is crucial for the maintenance of cellular functions and tissue integrity suggesting that cancer-induced changes in the stroma may contribute to cancer invasion and its biological behaviour. One of the major constituent of the tumour stroma is myofibroblasts. Myofibroblasts are differentiated host fibroblasts that express α-Sma as cytoplasmic microfilaments. They are considered as one of the modified stromal component which in recent years have been thought to have a role in the invasion and aggressive behaviour of odontogenic tumours too.
  
  
  OBJECTIVE
  To detect immunohistochemically the presence of myofibroblasts in solid/multicystic ameloblastoma and in unicystic ameloblastoma and to see if a relationship exists between the frequency and pattern of distribution of myofibroblasts and the behaviour of ameloblastomas.
  
  
  METHODS
  Ten cases each of solid/multicystic ameloblastoma and unicystic ameloblastoma were stained immunohistochemically for vimentin, α-SMA and desmin. The frequency and pattern of distribution of myofibroblasts in the two study groups were analysed and then compared with clinical and radiographic features of pain and cortical perforation respectively.
  
  
  RESULTS
  Immunohistochemical reaction for α-SMA (alpha Smooth Muscle Actin) showed positive cells in the stroma of both solid/multicystic and unicystic ameloblastomas. The mean number of myofibroblasts was more in unicystic ameloblastoma (UA) compared to Solid/Multicystic Ameloblastoma (SMA). Myofibroblasts expression was dense and arranged in the form of fascicles with indistinct cell borders in one case of follicular ameloblastoma, two cases of plexiform ameloblastoma and in a focal area of one case of type 1UA. In all other cases where the expression was noted, the myofibroblasts were spindle in shape with distinct cell boundaries.
  
  
  CONCLUSIONS
  The results of the study indicate that myofibroblasts alone may not play a role in the behaviour of ameloblastomas. This calls for determining the role of various other stromal components in the biological behaviour of ameloblastomas. Our study could not establish a correlation between pattern of distribution of myofibroblasts and the behaviour of ameloblastomas.
authors.affiliation: Senior Lecturer, Department of Oral Pathology, Rajarajeswari Dental College and Hospital , Bangalore, India .
authors.forename: Gowdara Prakash
authors.initials: GP
authors.lastname: Smitha
authors.affiliation: Reader, Department of Oral Pathology, The Oxford Dental College, Hospital and Research centre , Bangalore, India .
authors.forename: Sadhana
authors.initials: S
authors.lastname: Shenoy
authors.affiliation: Professor and Ex- HOD, Department of Oral Pathology, The Oxford Dental College, Hospital and Research centre , Bangalore, India .
authors.forename: Thondikulam Venakataraman
authors.initials: TV
authors.lastname: Narayan
authors.affiliation: Senior Lecturer, Department of Oral Pathology, KLE Dental College & Hospital , Bangalore, India .
authors.forename: Ranjita
authors.initials: R
authors.lastname: Jayaram
keywords: Biological behaviour; Cortical perforation; Pain; Stromal patterns