Infected intradural dermoid cyst without dermal sinus tract mimicking brain abscess: A case report

•An infected intradural dermoid cyst with no dermal sinus was exceptional.•Diagnosing infected dermoid cyst with no dermal sinus might be challenging.•Systemic antibiotic therapy after gross total resection was an effective treatment. Infection is a rare complication of intradural dermoid cyst. We reported an infected intradural dermoid cyst without dermal sinus tract mimicking brain abscess. A 4-year-old boy with no medical history complained of a palpable mass on his head. On examination, the occipital palpable mass was firm and immobile, had no redness, swelling, and pain. The preoperative MRI showed a well-defined, ring-enhancing lesion. White blood count was 12.8 × 109 cells/liter. We have sought no other infection sites. We encountered intraoperatively the pus from the infected mass invading subcutaneous layer and skull bone. We excised completely the tumor and carefully coagulated the residual capsule invading superior sagittal sinus. Histopathological examination was infected dermoid cyst. The infection agent was Staphylococcus aureus. The patient was received systemic antibiotic therapy for 21 days following oral antibiotics for 1 month. He was discharged with no complications. The diagnosis of infected dermoid cyst was often based on MRI images and especially dermal sinus tract. However, in the absence of a dermal sinus tract, preoperative diagnosing an infected dermoid cyst might be very challenging. The ideal treatment of the dermoid cyst was total resection of the cyst with the epithelial lining. Nevertheless, due to the benign nature of dermoid cyst, adequate gross total resection with meticulous hemostasis the residual capsule firmly adhering eloquent areas and major vessels was more appropriate. Diagnosing infected dermoid cyst with no dermal sinus might be challenging. Systemic antibiotic therapy after gross total resection was an effective treatment.