Table 2.

Diagnostic criteria to exclude differential diagnoses of adenoid ameloblastoma

Entity/ies	Diagnostic criteria
Adenoid ameloblastoma	A tumour composed of at least following three histopathological elements 1. Any histopathological subtype of ameloblastoma or a tumour showing ameloblast like cells and or stellate reticulum like cells, without the characteristic architectural arrangement of ameloblastoma 2. Adenomatoid odontogenic tumour showing at least one or more features such as duct like structures, glandular differentiation or epithelial whorls with local invasion 3. Dentinoid in a mature fibrous stroma It is not always essential to identify all architectural characteristics supportive of ameloblastoma or AOT as such a finding would result in a diagnosis of hybrid tumour or a collision tumnour. In addition, in the case of AOT, the most important finding is the local invasion that is not seen in conventional AOTs
Histopathological sub types of ameloblastoma	A solid tumour composed of ameloblast like cells and stellate reticulum like cells arranged in to follicles or interconnected strands. Presence of squamous metaplasia, granular cell change or desmoplasia depending on the sub type of ameloblastoma A cystic tumour composed of ameloblast like cells and or stellate reticulum like cells in the case of unicystic ameloblastomas Hypercellularity of the epithelial component and occasional mitoses may be present especially in conventional ameloblastomas
Adenomatoid odontogenic tumour	A solid or rarely cystic well circumscribed tumour (without invasion) composed of at least one or more features such as duct like structures, glandular differentiation or epithelial whorls, with or without calcifications and dentinoid. The majority of typical AOTs generally occur in female patients in the second decade of life with a predilection to anterior maxilla
Ameloblastic carcinoma	Majority present as long standing large lesions, histopathologically defined by a combination of cytological features associated with malignancy and histopathological pattern of an ameloblastoma. At least focally ameloblast like cells are present while in most areas loss of characteristic organization (peripheral ameloblast like cells and central stellate reticulum like cells) seen in ameloblastoma is lost. Features characteristic of malignancy such as vascular and perineural invasion, distant and regional metastasis may or may not be present
Odontogenic carcinoma with dentinoid	A tumour composed predominantly of clear cells with variable amounts of small round to basaloid cells. In some cases, there may be duct-like or pseudocystic structures and peripheral columnar cells with evidence of palisading. The common feature is the presence of variable amounts of dentinoid in a mature fibrous connective stroma, induced by the epithelial component
ES/PNET	A sarcoma composed of small round blue cells with Homer-Wright. Immunohistochemical investigations reveal CD99 and FLI-1 positivity. Adamantinoma like ES is an atypical variant that may show resemblance to case 2 of the presently described lesions
Aggressive adenomatoid odontogenic tumour	Histopathological features are similar to typical AOT. The lesion presents as a rapidly enlarging lesion cortical erosion
AOT with inductive changes	A lesion histopathologically similar to typical AOT with prominent inductive changes producing dentinoid