Mandibular ramus osteotomy for resection of a deep prestyloid parapharyngeal space mass with skull base extension: a case report and technical note

Abstract

Abstract Background Deep prestyloid parapharyngeal space (PPS) lesions with skull base extension may be difficult to access through standard surgical corridors because the mandibular ramus can restrict line-of-sight and instrument working angles, particularly near the carotid arteries and other critical neurovascular structures. In selected cases, exposure escalation may be considered on the basis of patient-specific corridor geometry rather than tumor size alone. Rare ectopic or extracranial pathologies may further complicate preoperative classification and operative planning. Case presentation A 61-year-old woman presented with a 1-year history of left-sided pharyngeal discomfort. Imaging demonstrated a well-circumscribed, predominantly cystic deep prestyloid parapharyngeal space mass abutting the medial surface of the mandibular ramus, extending to the skull base, and closely apposed to the internal and external carotid arteries without vascular encasement. Preoperative fine-needle aspiration cytology (FNAC) was considered but deferred after imaging review because the lesion was deep-seated, partially shielded by the mandibular ramus, closely adjacent to major vessels, and lacked a safe and diagnostically meaningful sampling trajectory to the mural nodule. Because standard approaches were expected to provide limited superior and posterolateral working angles near the carotid arteries, resection was performed through a mandibular ramus osteotomy to expand the lateral corridor. After controlled needle decompression of the cystic component to reduce capsular tension, the solid/capsular component was removed as a single specimen without piecemeal fragmentation. Estimated blood loss was approximately 100 mL. Histopathology based on hematoxylin-and-eosin morphology supported the diagnosis of adamantinomatous craniopharyngioma, showing peripheral palisading and compact “wet keratin”; however, immunohistochemical and molecular confirmation was not available. The postoperative course was uncomplicated, with preserved facial nerve function, normal occlusion and swallowing, unchanged maximum interincisal opening, and no inferior alveolar nerve-related symptoms. At 45 months after surgery, mandibular radiographs showed stable fixation hardware, and clinical functional status remained unchanged. Late postoperative cross-sectional imaging for tumor surveillance was not obtained. Conclusion In this single case, mandibular ramus osteotomy appeared to be a useful exposure-escalation option for a deep prestyloid parapharyngeal space/lateral skull base lesion in which mandibular obstruction, skull base extension, and carotid adjacency were expected to restrict line-of-sight and working angles through standard corridors. This report should be interpreted as a hypothesis-generating case report and technical note rather than evidence of superiority over other approaches. The absence of ancillary pathological confirmation, dedicated sellar imaging, and late cross-sectional surveillance imaging represents important limitations. Key clinical message For selected deep prestyloid parapharyngeal space lesions extending toward the skull base, operative planning should consider corridor geometry — including line-of-sight, instrument trajectory, working angles, and feasibility of circumferential dissection — in addition to tumor size.