PC1207: A Tiny Hole with Big Consequences: Infected Congenital Dermal Sinus Tract Leading to Spinal Abscess

Introduction: Sacral dimples are common finding present in 1-2% of newborns. Clues to presence of occult spinal dysraphism include cutaneous findings such as hemangioma, vascular lesions, tuft of hair, subcutaneous mass and size/depth and location of dimple from anal opening. Delayed diagnosis can lead to neurological symptoms secondary to cord tethering or infections from introduction of skin flora bacteria through sinus tracts.

Case Description: A 14-month-old female with a history of sacral dimple with cutaneous nevus simplex presented with acute abdominal pain and emesis. One month prior, she had purulent drainage from the dimple, treated with oral Clindamycin. Physical exam was significant for abdominal distention especially in the suprapubic area with tenderness on palpation, mid-sacral nevus simplex with subcutaneous painless, nonmobile, indurated mass with a central dimple. Neurological exam was concerning for absence of anal tone with bilateral lower extremity hypotonia, progressing to hyperreflexia. Abdominal ultrasound (US) showed a distended bladder and bilateral hydroureteronephrosis. Lumbar spine US showed a hypoechoic subcutaneous lobular lesion with tract extending to skin surface, suggesting a complicated cyst abscess. Magnetic resonance imaging (MRI) spine was significant for a sinus tract with a dorsal defect within the osseous spinal canal at S2-S3 with a nonenhancing cystic component within a tethered cord and enhancement of cord at L1-L2 extending into the sacral spinal canal (Figure 1 and 2). These findings were suggestive of a sacral dermal sinus tract, tethered cord with an intramedullary spinal abscess. Patient was started on intravenous antibiotics and subsequently underwent fenestration of sinus tract, laminectomy and drainage of abscess. Tissue biopsy confirmed the diagnosis of infected sacral intraspinal epidermoid cyst and dermal sinus tract with fibrofatty tissue and fistula tract filled with multiple hair strands. Wound culture grew methicillin sensitive staph aureus and antibiotics were tailored based on sensitivities with completion of a six week course. At discharge, the patient had resolution of all symptoms with repeat spinal MRI revealing decreased size of spinal canal abscess and edema.

Discussion: This case highlights the importance of recognizing sacral dimples which are associated with congenital tract leading to complications. Our patient had a dermal sinus tract which served as a portal of entry for pathogens causing an intramedullary spinal abscess as well as neurological symptoms from tethered cord.

Conclusion: Spinal dermal sinus tracts in addition to being a risk for serious infections are associated with inclusion cysts, tethered cord and spinal defects. Although sacral dimples are a common finding, cutaneous midline lesions, size and location of dermal pits should prompt providers to consider the possibility of underlying neural tube defects and evaluate them with the appropriate imaging.