Characterization of Histological Overlap Between Surgical Ciliated Cyst, Frontal-Ethmoidal Sinonasal Mucocele and Nasopalatine Duct Cyst

Introduction

Surgical ciliated cyst (SCiC) represents a late-occurring complication related to prior midface surgery or trauma, often presenting years even decades after the initial event. In the absence of correlative clinical history and imaging, distinguishing SCiC from similar appearing entities such as nasopalatine duct cyst (NPDC) or sinonasal mucocele (MC) may present a diagnostic challenge.

Materials and Methods

A retrospective search for patients diagnosed with SCiC, frontoethmoidal MC and NPDC at one institution between 2005 and 2022 was conducted. Clinical and imaging data were retrospectively reviewed and histopathologic features were analyzed and compared. Maxillary sinus mucoceles were excluded.

Results

Twenty-nine cases of SCiC, 11 frontoethmoidal MC and 8 NPDC with available slides were reviewed. While age at presentation was similar across these entities, SCiC showed a predilection for females in contrast to MC and NPDC. Microscopically, the cystic lesions showed histologic overlap if lined by atrophic squamoid epithelium with subepithelial fibrosis or hyalinization; a feature most common to SCiC (86%) and MC (82%), but also over half of NPDC cases. Respiratory (ciliated) epithelium was present within the specimens across all 3 entities. Seromucinous glands were identified in all 3 cohorts, but most frequently seen in MC (91%) compared to NPDC (3%) and SCiC (1 case). Cartilage was never identified in SCiC specimens, and skeletal muscle was never identified in MC. Well developed stratified squamous epithelium helped to distinguish NPDC (present) from SCiC and MC (absent).

Conclusions

While SCiC, NDPC, and frontoethmoidal MC demonstrate areas of histologic overlap, several histological contextual clues including assessment for cartilage, seromucinous tissue, skeletal muscle, and well-developed/mature stratified squamous epithelium may be diagnostically helpful, even in the absence of correlative clinical history and imaging. Additional study to include maxillary sinus mucoceles and antral pseudocysts will be essential to improve the practical utility of these findings.