Sublingual Pleomorphic Adenoma: An Extremely Rare Pediatric Case

Significance Statement

Pleomorphic adenoma is rare in children and is most commonly localized in the parotid gland. Sublingual gland localized pleomorphic adenoma is extremely rare. In the presence of an encapsulated, T2 hyperintense, contrasting lesion on magnetic resonance imaging, it should be kept in mind in the differential diagnosis. Definitive diagnosis is made histopathologically and surgical resection is the treatment of choice.

A 12-year-old girl presented to our center with a swelling on the right side under the chin which has gradually increased over the past 2 years. The patient exhibited no known disease or history of trauma or surgery. On clinical examination, the lesion was firm on palpation and not painful. There was no discoloration of the skin. No lymphadenopathy or accompanying findings were found in the cervical region. The patient underwent ultrasonography. A circumscribed hypoechoic lesion with a diameter of approximately 3 cm was observed in the submental area. Cystic openings and calcifications were observed within the mass. Color Doppler imaging demonstrated an internal heterogeneous blood supply. To determine the relationship between the mass and surrounding soft tissues, contrast-enhanced magnetic resonance (MR) imaging was performed. The images revealed a 32 mm × 32 mm × 29 mm smoothly circumscribed lesion in the right sublingual space, which was indistinguishable from the sublingual gland. On T1-weighted images, the mass was iso-hypointense with muscle tissue, while on T2-weighted images, it was heterogeneously hyperintense and had a hypointense capsule (Figure 1). The mass was not diffusion-restricted on diffusion-weighted images and demonstrated heterogeneous contrast enhancement on postcontrast sections (Figure 2). The patient was initially diagnosed with a benign lesion and underwent an ultrasound-guided tru-cut biopsy. Following a pathological examination, a diagnosis of pleomorphic adenoma was reached. Subsequently, the lesion was excised via a submental incision. A histopathological examination of the lesion confirmed the diagnosis of pleomorphic adenoma. The patient was discharged from the hospital with no complications.

Figure 1.

The T1-weighted coronal section image demonstrates a lesion (asterisk) that is iso-hypointense with muscle tissue and indistinguishable from the sublingual gland (arrow). In T2-weighted sagittal (B) and axial (C) sections, the mass (asterisk) is heterogeneously hyperintense and has a hypointense capsule (arrowheads).

Figure 2.

The mass (asterisk), which is hyperintense on the apparent diffusion coefficient image (A), is heterogeneously densely contrasted on postcontrast T1-weighted axial (B) and coronal (C) slices.

Salivary gland tumors represent 3% of all head and neck tumors in the pediatric population. Pleomorphic adenoma accounts for 60% to 70% of all tumors similar to the adult group. ¹ The most common site of occurrence is the parotid gland and minor salivary glands. It is more prevalent in individuals over the age of 10 years and exhibits a female predilection. Sublingual gland tumors represent 1% of all salivary gland neoplasms in adults. In children, it is exceedingly rare, with only a few documented cases in the literature.^2,3 It is a slow-growing mass and most commonly presents as a painless, firm, localized swelling. Radiological imaging is a valuable tool in the diagnostic and differential diagnostic processes. Ultrasonographic examination reveals a smoothly circumscribed, iso-hypoechoic lesion that may contain calcification. On MR imaging, small lesions exhibit homogeneous T1 hypointense and T2 hyperintense characteristics. In postcontrast sections, they are densely homogenously contrasted and do not restrict diffusion. As the lesions enlarge, heterogeneous intensities may be observed due to hemorrhage, necrosis, and cystic areas. The capsule, which is a relatively typical feature of pleomorphic adenoma, is observed as a hypointense rim on T2-weighted images. A definitive diagnosis is made on the basis of histological examination. Surgical resection is the preferred treatment for this neoplasm, as it carries the risk of malignant transformation. Postoperative recurrence is rare.^1,4,5