J Ped Surg Case Reports 12 (2016) 1e2
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Is pre-surgical imaging required for an asymptomatic posterior vertex subcutaneous dermoid? A case report Simon Ho a, b, *, Thang Ngo a a b
Nemours Children’s Hospital, 13535 Nemours Parkway, Orlando, FL 32827, USA University of Central Florida College of Medicine, 6850 Lake Nona Blvd, Orlando, FL 32827 USA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 15 May 2016 Accepted 12 June 2016
Scalp dermoid cysts are common etiologies of subcutaneous lump and bump lesions in the pediatric population, with incidence ranging from 15 to 22% (Crawford, 1990; McAvoy & Zuckerbraun, 1976). Midline scalp dermoid cysts have high risk for intracranial extension, with incidence reported to be 39e57% of cases (Wood, Couture, & David, 2012; Posnick, Bortoluzzi, Armstrong, & Drake, 1994). The following case illustrates a healthy thirteen-year-old boy who presented with asymptomatic enlarging subcutaneous posterior scalp mass who was consented for excision of the mass without pre-operative imaging, and was found to have an intracranial dermoid sinus tract intra-operatively. Post-operative imaging found an intracranial dermoid nodule which entailed an otherwise avoidable second-stage surgery to achieve complete resection. Ó 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Key words: Dermoid cyst Pediatric neurosurgery Cranial mass
Scalp dermoid cysts are common etiologies of subcutaneous lump and bump lesions in the pediatric population, with incidence ranging from 15 to 22% [1,2]. Intracranial extension of the dermoid is much rarer, with historical incidence between 1 and 2.4% [1]. However, midline scalp dermoid cysts are associated with a much higher incidence of intracranial extension, with studies reporting incidences of intracranial extension in midline dermoid cysts at 39e57% [3,4]. These intracranial extending lesions pass through skull defects and create a “dumbbell dermoid” connected by sinus stalk to the calvarium, and may extend intra-durally as far as the fourth ventricle [5]. To ensure a permanent cure, treatment must involve complete excision of the subcutaneous dermoid cyst and any underlying dermal sinus or intracranial component to prevent recurrent meningitis. Incompletely resected cysts can recur. Preoperative imaging, particularly MRI, is highly sensitive and of utmost importance in managing patients with palpable midline scalp masses [1,3,4,6,7]. Using MRI’s high soft tissue contrast resolution to map out detailed anatomy of the scalp lesion and any intracranial extension before surgery is paramount [6,7]. The following case illustrates the importance of obtaining pre-operative imaging in midline posterior scalp subcutaneous lesions in avoiding unnecessary follow-up surgery to achieve a permanent cure.
* Corresponding author. E-mail address:
[email protected] (S. Ho).
1. Case report We present the case of a thirteen-year-old boy with a subcutaneous palpable mass in the midline occipital region. The patient was referred by his primary care physician to a general surgeon at our hospital for the presence of a midline posterior scalp lesion that was enlarging in size and causing discomfort. The general surgeon characterized the lesion as a 3 cm 3 cm, mobile, non-tender, posterior scalp mass without skin changes, consistent with a lipoma. Consent was obtained for excision of congenital posterior scalp mass. At this time, there was no record of neuroimaging or neurosurgery consultation. During surgery and after excising the subcutaneous mass, the general surgeon found an unexpected patent epithelial lined tract under the scalp lesion, prompting recruitment of a neurosurgeon to the operating room. Further exploration in collaboration with the neurosurgeon showed the tract likely extended into the brain through a pinhole osteous defect. The neurosurgeon coagulated the opening on the calvarial surface and closed the case. He had no option but doing so since there was no pre-surgical imaging to guide him otherwise. The cystic lesion was submitted to pathology for evaluation, which confirmed the diagnosis of a dermoid cyst. The patient tolerated the procedure well, and was discharged home without complication. Unexpected findings during the procedure prompted the neurosurgeon to order a post-operative outpatient follow-up
2213-5766/Ó 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). http://dx.doi.org/10.1016/j.epsc.2016.06.004
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S. Ho, T. Ngo / J Ped Surg Case Reports 12 (2016) 1e2
Fig. 2. Sagittal T1 volumetric image of the brain at midline showed a subcutaneous tract connected to a bright T1 fat nodule intra-durally posterior to the cerebellum. Three arrows showed the tract and single arrow showed the fatty nodule.
Fig. 1. Axial T2 weighted image showed a small nodule with bright inner circle signal, a central and most peripheral dark ring signal consistent with a combination of fat, mineralization and possible calcification (arrow).
surgeon. However, if there is a connection into an intracranial component, as in our case, it is best resected by a neurosurgeon. If the general surgeon had ordered pre-operative brain imaging in this patient, a second surgery with its associated risks would have been completely avoided. 3. Conclusion
pediatric brain MRI with contrast to rule out an intracranial extension and further evaluate the existing tract. Sagittal T2 weighted images showed a quarter sized defect in the midline subcutaneous occipital region in keeping with postsurgical defect, and confirmed a sinus tract through the calvarium. This tract ended with an extra-parenchymal intradural nodule 10 6 7 mm (CC AP TR) superior to the cerebellum, hyperintense on T1 and T2 imaging, consistent with fat, mineralization and possible calcification (Figs. 1 and 2). There was minimal mass effect on the adjacent cerebellum. There was no abnormal contrast enhancement of the brain parenchyma or meninges to suggest meningitis. The patient and family was counseled on the imaging findings and scheduled for secondstage surgery to excise the intracranial tract and intracranial nodule dermoid by a neurosurgeon to achieve permanent cure. 2. Discussion Subcutaneous lump and bump scalp lesions are very common in the pediatric population. If the lesion is midline in location, then pre-operative imaging is a must, particularly brain MRI, to look for any intracranial component [6,7]. If there is no connection into an intracranial component, it can be safely managed by a general
This case illustrates two take home points. A midline scalp mass in a pediatric population must receive pre-surgical planning imaging, preferably MRI brain with contrast. Consult with a neurosurgery colleague is also a good idea. References [1] Crawford R. Dermoid cyst of the scalp: intracranial extension. J Pediatr Surg Mar 1990;25(3):294e5. [2] McAvoy JM, Zuckerbraun L. Dermoid cysts of the head and neck in children. Arch Otolaryngol Sep 1976;102(9):529e31. [3] Wood J, Couture D, David LR. Midline dermoid cyst resulting in frontal bone erosion. J Craniofac Surg Jan 2012;23(1):131e4. [4] Posnick JC, Bortoluzzi P, Armstrong DC, Drake JM. Intracranial nasal dermoid sinus cysts: computed tomographic scan findings and surgical results. Plast Reconstr Surg Apr 1994;93(4):745e54. discussion 755e746. [5] Sinclair RD, Darley C, Dawber RP. Congenital inclusion dermoid cysts of the scalp. Australas J Dermatol 1992;33(3):135e40. [6] Orozco-Covarrubias L, Lara-Carpio R, Saez-De-Ocariz M, Duran-McKinster C, Palacios-Lopez C, Ruiz-Maldonado R. Dermoid cysts: a report of 75 pediatric patients. Pediatr Dermatol Nov-Dec 2013;30(6):706e11. [7] Sorenson EP, Powel JE, Rozzelle CJ, Tubbs RS, Loukas M. Scalp dermoids: a review of their anatomy, diagnosis, and treatment. Childs Nerv Syst Mar 2013; 29(3):375e80.
