Choanal Polyp with Osseous Metaplasia: Radiological and Therapeutic Management of a Rare Case and a Review of Bone Metaplastic Lesions of Sinonasal Tract

Abstract

BACKGROUND Osseous metaplasia is a heterotopic normal bone in soft tissues. It is occasionally found in mucosal polyps of the external auditory canal, tongue, gut, stomach, nasal cavity, and uterus. Choanal polyp with osseous metaplasia originating from the lateral wall of the nasopharynx has not been previously reported. In fact, osseous metaplasia in nasal polyps represents a very uncommon histological finding with only 12 cases described in the literature. CASE REPORT We reported here, the clinical, radiological, and therapeutic management of a nasopharynx choanal polyp in a patient with severe nasal obstruction and rhinolalia history. Endoscopic examination of nasal cavities revealed a polypoid-like mass in the left nasal fossa, extending to the choanal area and nasopharynx. Computed tomography scan and contrast-enhanced magnetic resonance imaging confirmed the presence of a solitary and lobulated mass in the choanal area and nasopharynx. We performed the removal of the mass through careful hemostasis of left sphenopalatine artery using both transnasal and transoral paths, with no complications for the patient. Histopathological examination of the biopsy revealed a benign inflammatory polyp with osseous metaplasia. No recurrence was noted 24 months after surgery. CONCLUSIONS The incidence of ossifying areas in nasal polyps is very low, with only 12 cases reported in the literature. Ossifying polyps originating from the lateral wall of nasopharynx has never been reported before. The use of a combined endoscopic and transoral surgical approach was shown to be reliable in terms of adequate exposure and visualization of the lesion, control of bleeding, and complete removal of the mass.

Figure 1.

Computed tomography scan, sagittal plane: solitary, lobulated mass with clustered radio dense material, suggesting ossification. The mass filled the posterior part of left nasal fossa and extended to the nasopharynx.

Figure 2.

Magnetic resonance imaging with contrast, axial plane: presence of the mass in left choana, that appears to be originated from rhinopharynx with calcific aspect. Low enhancement after contrast medium injection.

Figure 3.

Surgical specimen, 5×3×2 cm.

Figure 4.

Histological findings, the arrows show mature bone areas in the subepithelial chorion, organized in trabeculae. Within the trabeculae is interposed some stroma.