Odontogenic myxoma (OM) is a rare, benign, and locally aggressive tumor. It tends to occur in the posterior maxilla and mandible and is often associated with root resorption and perforation of cortex. Histopathologically, there is a proliferation of spindle, bipolar, and stellate cells, with bland nuclei within a myxoid to infrequently fibromyxoid extracellular matrix. Long, thin residual bony trabeculae are often seen floating within the spindle cell proliferation because of the infiltrating nature of this tumor, and these trabeculae impart a "soap bubble" or "tennis-racket" radiologic appearance. No syndromic association of OM has been reported. Although similar histopathologic features are shared with cardiac myxoma and soft tissue myxoma, mutations in the GNAS gene have not been identified in OM to date, and only 2 of 17 OMs showed mutations in the PRKAR1A gene. In this report, we describe a case of OM in a patient with constitutional 1q21 microduplication, a locus that harbors genes encoding certain proteins in the cAMP-dependent protein kinase A (PKA) signaling pathway, including G-protein-coupled receptors and 1 phosphodiesterase interacting protein. Review of the literature describes the key clinical features and molecular pathogenesis of 1q21 microduplication, as well as highlighting the role of PKA signaling pathway in the pathogenesis of myxomas in general.
Keywords: GNAS1; PKA; PRKAR1A; odontogenic myxoma.