Malignant chondroid syringoma with calvarial invasion and intracranial extension

Introduction. Malignant chondroid syringoma (MCS) is an exceptionally rare malignant adnexal tumor with aggressive biological behavior. This report describes a rare case of frontotemporal MCS with calvarial invasion and intracranial extension. Case Outline. A 65-year-old male presented with a recurrent ulcerated cutaneous tumor in the left frontotemporal region, with four previous surgical excisions that had been histopathologically diagnosed as malignant basal cell carcinoma. Preoperative computed tomography (CT) and magnetic resonance imaging (MRI) revealed calvarial osteolysis with intracranial tumor extension. Radical excision with craniectomy, dural resection, and duraplasty was performed, followed by reconstruction using a local transposition flap and a secondary free split-thickness (Thiersch) skin graft. Histopathological and immunohistochemical analyses confirmed MCS with bone and perineural invasion and tumor involvement of the deep surgical margin (R1). Adjuvant conformal radiotherapy was administered. No recurrence or metastasis was observed during a nine-month follow-up period. Conclusion. MCS may clinically mimic other cutaneous malignancies, which can lead to delayed diagnosis. Wide surgical excision and long-term follow-up are essential for adequate disease control.