Case report: Implantation metastasis following stereotactic biopsy of pineal parenchymal tumor of intermediate differentiation in an adult patient: An exceptionally rare complication.

Implantation metastasis following stereotactic biopsy in the brain had been reported as a rare complication. A 36-years-old female patient was treated with ventriculoperitoneal (VP) shunt and stereotactic biopsy of a pineal parenchymal tumor of intermediate differentiation (PPTID) with hydrocephalus. The patient underwent five cycles of radiotherapy on the pineal area. Seven years after the procedure, the patient developed left hemiparesis with the brain MRI findings showing an enhanced mass along the biopsy tract. Craniotomy tumor removal was carried out and the pathological assessment was consistent with those of the PPTID. Radiation on metastase area and craniospinal was subsequently performed. The patient was disease-free during the 2-year follow-up assessments. The potential occurrence of implantation metastasis following the stereotactic biopsy of PPTID should be considered in the treatment plan and follow-up assessments and evaluations. Expanding the radiation area to cover the entire biopsy tract may be favorable to lower the risk of implantation metastasis.