Mesenchymal hamartomas of the pediatric head and neck.

We describe the fifth published report of a mesenchymal hamartoma presenting as a cheek mass. A 5-month-old infant was brought to our institution for evaluation of an enlarging left-sided congenital cheek mass. Over time, the lesion had begun to cause significant facial asymmetry and oral incompetence. Radiologic imaging revealed an approximate 2.5 × 3.5-cm, noncystic lesion located in the left buccal space, separate from the mandible and surrounding the salivary glands. Magnetic resonance imaging (MRI) sequences demonstrated an isointense, T1-weighted lesion with avid gadolinium uptake, and increased intensity of T2-weighted sequences. The patient subsequently underwent biopsy and subtotal resection through a left gingivobuccal incision with the goal of improving lip contour and facial symmetry. Histologic examination revealed an admixed arrangement of mature smooth muscle, vascular, adipose, and neural tissue elements within a slightly myxoid stroma, consistent with a mixed mesenchymal hamartoma. An 8-month postoperative MRI demonstrated near-total removal without evidence of regrowth. While rare, hamartomas should be included in the differential diagnosis of a slow-growing pediatric head and neck mass. Gross total resection may provide cure; however, given this lesion's benign nature, less-than-complete resection should be considered when lesions infiltrate opposing critical structures. Thorough clinical and histologic evaluation is critical to avoid overly aggressive treatment and unnecessary morbidity.