Calcifying odontogenic cyst: dilemma in classification.

Calcifying odontogenic cyst (COC) shows extreme diversity in its clinical and histopathological features, as well as in its biological behavior. Because of this diversity, there has been confusion and disagreement on the terminology and classification of this lesion. Attempts to classify COC can be divided into two concepts: monistic and dualistic. We present a case of COC with coexisting histopathologic features of a cyst and a neoplasm, thus posing a dilemma in the terminology used to categorize and classify it.