BACKGROUND Teratomas are rare congenital tumors arising from pluripotent germ cells and contain tissues derived from all three germ layers: ectoderm, mesoderm, and endoderm. Intracranial teratomas are uncommon, accounting for less than 0.5% of all central nervous system tumors, and typically occur in midline structures such as the pineal or suprasellar regions. Primary involvement of cranial bones with transosseous extension is exceptionally rare. These lesions may lead to progressive cranial deformity and local bone destruction. While isolated cases involving the petrosal bone have been reported, localization at the cranial vault is exceedingly uncommon. To our knowledge, this report describes the first case of a transosseous teratoma involving the frontal and parietal bones.
CASE PRESENTATION A 39‑year‑old male presented with persistent headache and vertigo, associated with a subcutaneous swelling at the bregma that progressively enlarged following a hair transplant procedure. Imaging revealed an osteolytic transosseous lesion involving both the external and internal cortical tables, with intraspongious extension and multiple hair follicles embedded within the mass. The patient underwent complete surgical excision, including resection of the outer cortical bone to delineate tumor margins and achieve total removal clearly. Histopathological examination confirmed the diagnosis of a mature teratoma. The postoperative course was uneventful, and the patient was discharged on the third postoperative day without neurological deficits.
DISCUSSION Transosseous teratomas of the cranial vault are extremely rare. Their pathogenesis is thought to involve aberrant migration of germ cells during embryogenesis, resulting in ectopic growth within bone. Differential diagnosis includes dermoid and epidermoid cysts, osteolytic skull tumors, and other germ cell neoplasms. Complete surgical excision remains the treatment of choice to prevent recurrence. Given the potential for malignant transformation, long‑term clinical and radiological follow‑up is recommended.
CONCLUSION: This case underscores the importance of early diagnosis and complete surgical resection in the management of transosseous cranial teratomas. Further reports are needed to better define optimal management strategies for these rare lesions.
