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unicystic ameloblastoma
Saturday 9 May 2009
Unicystic ameloblastoma is a variant of ameloblastoma. It is one of the most difficult of the odontogenic lesions to diagnose.
Clinically it may be asymptomatic or may expand the cortical plate and may resorbe the tooth structure. Radiographically it presents as a unilocular radiolucency.
Microscopically it shows a palisaded basal layer, polarization of basal cell nuclei to the end of the cells, hyperchromatism of the basal cells, vacuolation of the basal cell cytoplasm, stratum spinosum like stellate reticulum and sometimes keratinization.
Portions of unicystic ameloblastoma do not show ameloblastic epithelium and secondary inflammation make the diagnosis very difficult.
Importantly, ameloblastic epithelium must not penetrate the wall of the cyst. If so, the lesion behaves as a solid ameloblastoma.
Microscopic variants include luminal type in which the ameloblastic epithelium is confined to the luminal layer and the intraluminal in which nodules of ameloblastic epithelium project into the cyst lumen.
These lesions are destructive and 15% may recur after simple enucleation.
Differential diagnosis
unicystic ameloblastoma
dentigerous cyst
odontogenic keratocyst
Credits
USCAP 20058
