Periapical Cyst and Odontogenic Remnants on Osseous Mandibulectomy Margins: Two Diagnostic Pitfalls.

In this article, we describe 2 high-stake diagnostic pitfalls that occurred in a single patient having undergone partial glossectomy and marginal mandibulectomy for invasive squamous cell carcinoma. Margins were grossly uninvolved. Histopathology showed a moderately differentiated squamous cell carcinoma. Microscopic evaluation of margins was challenging, as the inferior osseous margin submitted en face showed spongiotic epithelium with mixed chronic and acute inflammation, representing a periapical cyst after correlation with the gross examination. Another section of the osseous margin showed a small non-atypical epithelial nest, consistent with an odontogenic epithelial rest. We wish to raise awareness of these diagnostic pitfalls as a bone margin with such epithelial foci could be misinterpreted as positive, with serious therapeutic consequences.