Case Presentation: A 3-year-old girl presented with two years of monthly recurrent left periorbital swelling. The swelling was often accompanied by subjective fevers and pain. Prior episodes were treated with courses of antibiotics with some associated improvement but incomplete resolution. The child was otherwise healthy with normal growth and development.She had mildly tender non-erythematous swelling of the left upper and lower eyelid without conjunctival injection. There was no proptosis, extraocular muscles were intact, and pupils were round and equally reactive. The remainder of her exam was normal. Peripheral WBC was 15.4 x 10^9/L. Her remaining labs, including c-reactive protein and erythrocyte sedimentation rate, were within normal limits.MRI of the brain revealed a T1 and T2 hyperintense, cystic lesion with enhancing mural nodule centered in the left pterygopalatine fossa and infratemporal fossa (Figure 1). Sinus CT showed a 3.1 x 1.7 cm expansile lesion centered within the left pterygopalatine fossa without aggressive features.She was taken for endoscopic endonasal biopsy of the lesion and a well-encapsulated cystic lesion with brown, oily fluid was encountered (Figure 2). Frozen section was negative for malignancy and fungal and bacterial cultures showed no growth. Permanent pathology revealed a mature teratoma characterized by minor salivary glands, sinonasal mucosa, and pancreatic tissue with exocrine cells and islets (confirmed by INSM-1 immunostain, a neuroendocrine marker). She did well after surgery and was discharged on post-operative day 1.

Discussion: The general pediatrician should be familiar with teratomas, benign germ cell tumors that are rare but can present in multiple anatomic regions. Pediatric teratomas are most commonly found in the sacrococcygeal, gonadal, or mediastinal regions, with only 6% of tumors affecting the head and neck (1). Tumor location does appear to be age-dependent, with extragonadal tumors occurring primarily in infants and very young children. Teratomas can be further classified as mature versus immature based on tissue differentiation, with immature teratomas having higher potential for recurrence or metastasis (1). Immature teratomas of the head and neck most commonly present in early infancy (2). Mature teratomas of the head and neck, as in our case, have been reported (3) but are unusual and may involve the neck, face, oropharynx, nasopharynx, or orbit. The clinical presentation may mimic orbital cellulitis, though with a chronic course unresponsive to antibiotic therapy. Radiology evaluation to best characterize the lesion pre-operatively is a critical component of patient care. Treatment is surgical, with generally an excellent prognosis.

Conclusions: In conclusion, pediatric providers should consider masses such as teratoma in the differential for periorbital edema not responsive to typical treatment. Our patient is one of the first reported cases of mature teratoma in the infratemporal fossa in a pediatric patient.

IMAGE 1: Figure 1. Coronal (A) and Axial (B) views of a T1-weighted MRI with Gadolinium demonstrating a rim-enhancing cystic lesion in the left infratemporal fossa abutting the orbital apex

IMAGE 2: Figure 2. Intraoperative endoscopic images. (A) Posterior maxillary wall (PMW) and Medial maxillary wall (MMW) has been partially resected to expose the anterior tumor wall in the infratemporal fossa. (B) Tumor wall has been entered to expose cystic cavity. (C) Cyst wall has been dissected free from infratemporal fossa and CN V2 Neurovascular Bundle (NVB) is seen entering the tumor capsule.