[Respiratory epithelial adenomatoid hamartoma of the nose and nasal sinuses : a rare differential diagnosis of nasal polyposis]

Olfactory Epithelial Hamartoma: A New Subtype of Sinonasal Hamartoma

Sinonasal epithelial hamartomas occurring in adults are classified as seromucinous hamartoma (SMH) or respiratory epithelial adenomatoid hamartoma (REAH). We describe herein a novel subtype of adult sinonasal hamartoma that contains olfactory epithelium, a histologic feature not previously reported in the literature. Our pathology department database was retrospectively searched for sinonasal hamartomas containing areas of olfactory epithelium. Six relevant cases (3 male and 3 female patients; age, 30 to 77 y) were retrieved, and available pathology slides and clinical and imaging data from patient charts were reviewed. Five of the lesions were unilateral solitary, polypoid, pedunculated masses, 38 to 80 mm in length, lodged in the nasal olfactory cleft. The sixth lesion was associated with bilateral nasal polyposis, and its precise localization was not known. All patients were treated by transnasal endoscopic surgery. None of the 3 patients who had received adequate follow-up evaluation exhibited recurrence. Histologically, all lesions resembled SMH or REAH, with areas of olfactory epithelium comprising olfactory receptors and sustentacular and basal cells. Olfactory epithelium was observed at the lesion surface or in invaginated gland-like structures, and it contained focal aggregates of filamentous cell processes. Some olfactory receptor cells or cell processes were also present in the seromucinous gland component of lesions. Olfactory receptor cells expressed CD56 (neural cell adhesion molecule), and the filamentous aggregates contained CD56, neurofilaments, and synaptophysin. Aside from SMH and REAH, we have described a third subtype of adult sinonasal hamartoma-olfactory epithelial hamartoma-which shares the benign character of the other 2.

Respiratory Epithelial Adenomatoid Hamartomas: An Increasingly Common Diagnosis in the Setting of Nasal Polyps

Background

Respiratory epithelial adenomatoid hamartomas (REAH) are benign nose neoplasms found in the nasal cavity and sinuses. Symptoms include anosmia, nasal obstruction, facial pressure, and rhinorrhea. Although previously thought to be rare, these tumors are being increasingly recognized on pathology in patients undergoing endoscopic sinus surgery. However, REAH is difficult to diagnose before surgery because it may mimic other entities, such as nasal polyps or inverted papilloma, and is often found incidentally only after surgery.

Objective

The aims of this study were to (1) add an additional case series of REAH to the literature, (2) report unique imaging findings on computed tomography and magnetic resonance imaging, and (3) pool and summarize all available data from existing publications.

Methods

Retrospective chart review from years 2004 to 2015 and a literature review

Results

Twenty-three cases were found in our case series, which included 12 men (52%) and 11 women (48%), with a mean age of 59 years. No cases were found before 2007. Lund-Mackay scores were comparable with those found in chronic rhinosinusitis without nasal polyposis. Imaging consistently demonstrated a discoid-shaped mass at the olfactory cleft. Fifty previous publications were found (4 prospective, 11 retrospective studies, 9 case series, 26 cases reports), which included 660 patients diagnosed with REAH. Pooled data revealed a mean age of 54 years (range, 9–86 years) and a male to female ratio of 3:2.

Conclusion

The results of our study further refined the average age at which REAH diagnosis occurs as 54 years old, although it may occur at any age. There is a clear male-to-female predominance (3:2). In addition, olfactory cleft widening and discoid soft tissue at the olfactory cleft are hallmark radiographic findings. The vast majority of published cases occurred during the past 4 years, which indicated increased recognition of REAH.