Pleomorphic dermal sarcoma of the scalp with intracranial space involvement: management of a rare entity. Illustrative case.

backgroundExophytic tumors of the calvaria (ETCs) remain a challenging pathology because of their complex management. The authors discuss the case of a woman with a large exophytic mass of the right frontotemporal region and underline their decision-making process on the management of this unique case and possible similar ones. OBSERVATIONS: Neuroradiological findings showed a calvarial tumor with both epicranial and intracranial extension involving the frontotemporal bone with a mixed component (lytic and sclerotic) and dural infiltration with a pseudonodular pattern. A wide en bloc excision from the skin to the dura mater was performed. The compound 5-aminolevulinic acid (5-ALA) was not very useful in identifying the tumor boundaries. One-step cranioplasty and a skin pedicle flap were used to reconstruct the anatomical defect. Acellular dermal matrix was used to repair the uncovered calvaria. Pathological examination confirmed the diagnosis of pleomorphic dermal sarcoma (PDS). LESSONS: In the evaluation of an ETC, PDS should be considered. Wide en bloc excision, if achievable, should be considered the gold standard. The 5-ALA was not helpful, and a pedicle skin flap could be considered as a less invasive alternative to microsurgical reconstruction. The use of an acellular matrix implant on the contralateral exposed galea increases the rate of reconstruction success. https://thejns.org/doi/10.3171/CASE24457.