Abscedation of posterior fossa dermoid cysts

Abstract

Dermoid cysts of the posterior fossa are uncommon. When associated with a dermal sinus, these cysts are often diagnosed during early childhood. The main risk of such an association is contamination of the cyst leading to abscedation of the dermoid itself or formation of daughter abscesses within the cerebellar hemisphere. We recently treated a 20-month-old girl who had a congenital dermal sinus leading to an intradural dermoid cyst. In addition to the midline dermoid cyst, computerized tomography revealed an enhancing lesion extending into the adjacent left cerebellar hemisphere. Suboccipital craniectomy was undertaken after 2 days of external ventricular drainage, and the infected dermoid and adjacent cerebellar abscess were excised. Cultures of the operative specimen revealed Corynobacterium aquaticum, Enterobacter sakazakii and Enterobacter cloacae, requiring 6 weeks of intravenous antibiotic therapy consisting of ceftriaxone, penicillin and gentamicin. A diligent literature search revealed only 24 sporadic cases reported over a period of 56 years. All 24 cases were in children (mean age 17 months), and one-third were in infants under the age of 1 year. All but 1 of these patients underwent posterior fossa surgery, with mortality and morbidity rates of 13% and 10%, respectively. Eleven (40%) children had suppuration within the cerebellar parenchyma, while the rest had abscedation of the dermoid cyst alone. Among the cases reviewed S. aureus was the most common agent, occurring with a probability of 64%. Key issues for appropriate management of these benign lesions are discussed.

Epidemiology, Etiology, Pathogenesis, and Diagnosis of Recurrent Bacterial Meningitis

“…The spectrum of organisms causing bacterial meningitis in the group with occipital lesions consists predominantly of constituents of the skin flora, with S. aureus being the most commonly isolated organism (198,206). In contrast, in infants and young children with dermal sinuses in the lumbosacral location, gram-negative organisms, particularly E. coli, and enterococci are the most common causative organisms of meningitis, most likely secondary to fecal contamination (10,115).…”

Analysis of the growth pattern of a dermoid cyst

“…14 In the occasional case reports describing dermoid cysts in the pediatric population, the cysts were associated with posterior fossa abscess formation and carried a high rate of mortality and morbidity. 26 This highlights the importance of early treatment of these lesions. Gross-total resection whenever possible remains the mainstay of treatment for dermoid cysts.…”

Posterior Fossa Dermoid Cysts Causing Cerebellar Abscesses

“…However, cerebellar abscesses as a complication of posterior fossa dermoid cyst and dermal sinus are exceptional, and only 16 cases are reported in the literature at present [1, 3, 4,6,7,8,9,10,11,12,13,14,15,16]. …”

“…Treatment may consist of antibiotics alone or antibiotics with abscess aspiration or total excision [1, 4, 6]. …”

“…More rarely, dermoid cysts may communicate with the skin through a narrow tract lined by epithelium (dermal sinus) which, therefore, contains the glandular architecture of the skin, promoting colonization by microorganisms. Microorganisms may travel into the cyst with the potential risk of deeper suppurations through this communication [3, 4]. The meningitic presentation of dermal inclusions around the occipital protuberance, particularly atypical staphylococcal or Gram-negative forms, is commonly reported [5].…”