HistoryA 43-year old Black female complained of sinus pressure and was found to have a mass of the right ethmoid sinus. Radiographic FeaturesA T1-weighted fat-suppressed (FS) post-clear coronal magnetic resonance imaging (MRI) study ( Fig. 1) revealed right mid-level ethmoid air cells that were expanding the sinus cavity. A slightly lower density signal compared to brain was noted, at 35 Hounsfield units, and was found to be isointense with skeletal muscle. Notably, this coronal image showed that the mass was not descending from the cranial compartment, thereby effectively ruling out an encephalocele. A T1 axial FS MRI (Fig. 2) showed bone remodeling as the tumor had eroded through the lamina papyracea at the medial wall of the orbit. A fluid attenuated inversion recovery MRI (Fig. 3) indicated the absence of bright signals to indicate hemoglobin, necrosis, calcification, or proteinaceous debris. No edema was noted in the medial rectus muscle and no infiltration of fat of the orbit was identified, suggesting a non-aggressive nature to this lesion. DiagnosisThe hematoxylin and eosin stained whole mount histologic section of a representative sample of the surgical specimen (Fig. 4) showed numerous irregularly shaped lobules of tissue with varying zones of cellularity. As shown in Fig. 5, there were more cellular areas consisting of bland appearing, but morphologically heterogeneous cells, including stellate and spindled cells with oval nuclei and eosinophilic cytoplasm with indistinct outlines. These cells were contained within a pale blue myxo-chondroid background stroma of varying tinctorial shades and occasionally arranged in a sieve-like pattern in the more myxoid areas. A subtle microlobular pattern characterized by a cellular periphery surrounding a hypocellular central area was noted as an occasional feature. Sparse numbers of granular appearing, polygonal shaped calcifications were identified within the specimen but not as a prominent feature; nor were they interpreted to be an inclusion or entrapment of the surrounding bone structures. Mitotic figures or cells displaying any amount of cellular atypia were not noted. In addition, there were no foci of distinct Disclaimer The opinions and assertions expressed herein are those of the authors and are not to be construed as official or representing the views of the Department of the Navy, Department of the Air Force or the Department of Defense. I certify that all individuals who qualify as authors have been listed; each has participated in the conception and design of this work, the writing of the document, and the approval of the submission of this version; that the document represents valid work; that if we used information derived from another source, we obtained all necessary approvals to use it and made appropriate acknowledgements in the document; and that each takes public responsibility for it. J. T. Castle

A 9-year-old male with a non-contributory medical history presented with left mandibular swelling. His mother had first noticed swelling in the area 2 months earlier, but stated that it seemed to resolve, only to develop again over the last 2 weeks. The boy had no complaints of pain, tenderness or altered sensation of his lower lip.Extraoral examination revealed mild facial asymmetry with enlargement of the body region of the left posterior mandible. The overlying skin lacked erythema or warmth and no anesthesia or paresthesia of the left lower lip was detected. Intraoral examination showed marked buccolingual expansion of the mandible centered on tooth #19 with vertical enlargement to the height of the occlusal plane; tooth #19 appeared ''engulfed.'' The mucosa was intact and of normal color (Fig.

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