A Unique Case of Frontotemporal Dermoid Cyst Presenting as Orbital Cellulitis.

Dermoid cysts are benign developmental anomalies that can occur anywhere along the neuroaxis or embryonic lines of fusion. While intracranial dermoid cysts at the midline frequently have an associated nasal or subcutaneous sinus tract, it is quite rare to encounter an intracranial dermoid cyst off the midline with a lateral sinus tract. Standard practice for the treatment of dermoid cysts is surgical resection to minimize the risks of meningitis, abscess, mass effect, neurologic deficit, and/or death.  A 3-year-old male with a history of DiGeorge syndrome presented with right orbital cellulitis and a right-sided dermal pit. Computed Tomography (CT) imaging demonstrated a dermal sinus tract with an associated lytic bone lesion within the right sphenoid wing and posterolateral orbital wall with intracranial extension. The patient was taken to the operating room in conjunction with plastic surgery for resection of the dermal sinus tract and intraosseous dermoid.  This case presents a rare occurrence of a non-midline, frontotemporal dermal sinus tract associated with a dermoid cyst with intracranial extension presenting with pre- and post-septal orbital cellulitis. Important considerations include preservation of the frontal branch of the facial nerve, preservation of orbital structure and volume, complete surgical resection to prevent infectious complications including meningitis, and a multidisciplinary surgical approach with plastic surgery, ophthalmology, and/or otolaryngology.

Immunopathogenesis of Craniotomy Infection and Niche-Specific Immune Responses to Biofilm.

Bacterial infections in the central nervous system (CNS) can be life threatening and often impair neurological function. Biofilm infection is a complication following craniotomy, a neurosurgical procedure that involves the removal and replacement of a skull fragment (bone flap) to access the brain for surgical intervention. The incidence of infection following craniotomy ranges from 1% to 3% with approximately half caused by Staphylococcus aureus (S. aureus). These infections present a significant therapeutic challenge due to the antibiotic tolerance of biofilm and unique immune properties of the CNS. Previous studies have revealed a critical role for innate immune responses during S. aureus craniotomy infection. Experiments using knockout mouse models have highlighted the importance of the pattern recognition receptor Toll-like receptor 2 (TLR2) and its adaptor protein MyD88 for preventing S. aureus outgrowth during craniotomy biofilm infection. However, neither molecule affected bacterial burden in a mouse model of S. aureus brain abscess highlighting the distinctions between immune regulation of biofilm vs. planktonic infection in the CNS. Furthermore, the immune responses elicited during S. aureus craniotomy infection are distinct from biofilm infection in the periphery, emphasizing the critical role for niche-specific factors in dictating S. aureus biofilm-leukocyte crosstalk. In this review, we discuss the current knowledge concerning innate immunity to S. aureus craniotomy biofilm infection, compare this to S. aureus biofilm infection in the periphery, and discuss the importance of anatomical location in dictating how biofilm influences inflammatory responses and its impact on bacterial clearance.