case_images: PMC10559566_01
case_images: Histopathology. Poorly differentiated sinonasal neuroendocrine carcinoma. (a) This poorly differentiated tumor grows in nests and trabeculae of cells; the tumor is composed of small to medium sized cells with hyperchromatic nuclei and numerous mitoses. (b and c) Immunohistochemistry: Expression of low molecular weight cytokeratin and chromogranin, respectively.
case_images: SNI-14-320-g001.jpg
case_images: PMC10559566_01_SNI-14-320-g001.jpg
case_images: F1
case_images: She underwent a first endonasal biopsy that reported an unresectable tumor in the right nasal cavity, with negative markers for esthesioneuroblastoma; a microscopic focus of poorly differentiated carcinoma with positive CKAE1/AE3 and negative CD56 and PS100 was reported [Figure 1].
case_images: Preoperative magnetic resonance imaging. Coronal T1WI (a and b), sagittal T1WI (c), and axial T1WI. A noncalcified heterogeneous mass with origin in the right nasal cavity with irregular infiltration to ipsilateral ethmoid cells and orbit, causing nasal septum displacement and skull base erosion, with slight frontal lobe displacement can be observed. Uninvolved pituitary gland and sellar region are shown in Figure 1b.
case_images: SNI-14-320-g002.jpg
case_images: PMC10559566_01_SNI-14-320-g002.jpg
case_images: F2
case_images: Afterward, magnetic resonance imaging (MRI) was performed [Figure 2], revealing an extra-axial mass that caused skull base erosion, and displacement of the right frontal orbital region, without invasion of brain parenchyma or meninges.
case_images: Intraoperative images. The tumor was bulging through the right nare (a) and was largely calcified, occupying the entire nasal cavity (b). After drilling the osseous portion of the tumor, the sella and anterior fossa were exposed (c). Further, drilling was carried out until exposure of the anterior fossa and orbit (asterisk) was achieved (d). The tumor invading the anterior fossa was dissected up to the normal dural margins (e). Complete removal of the intradural portion of the tumor was achieved (f).
case_images: SNI-14-320-g003.jpg
case_images: PMC10559566_01_SNI-14-320-g003.jpg
case_images: F3
case_images: A Draff III procedure was performed for anterior skull base dissection, communicating the frontal sinuses with the nasal cavity [Figure 3].
case_images: Reconstruction. After tumor removal, multilayered reconstruction was performed using an inlay dural substitute (a) and fascia lata graft (b) followed by an onlay fascia lata graft (c). An anteriorly based pedicled pericranial flap was harvested from a bicoronal incision and advanced through the nasion to cover the defect (d).
case_images: SNI-14-320-g004.jpg
case_images: PMC10559566_01_SNI-14-320-g004.jpg
case_images: F4
case_images: To repair the defect, the dural substitute was placed in an inlay fashion followed by autologous fascia lata; pericranium was extracted from a previous bicoronal incision, and it was used to finally cover the defect [Figure 4].
case_images: Postoperative magnetic resonance imaging. Coronal T1WI C+ (a and b), sagittal T1WI C+ (c), and axial (d), T1WI C+. No residual lesion or evidence of skull base involvement is observed. The straight gyri of both frontal lobes present areas of encephalomalacia, without evidence of abnormal enhancements.
case_images: SNI-14-320-g005.jpg
case_images: PMC10559566_01_SNI-14-320-g005.jpg
case_images: F5
case_images: The patient presented an uneventful postoperative course with symptomatic improvement; an MRI was conducted [Figure 5], finding no residual lesion or compromise of adjacent structures.