Sinonasal respiratory epithelial adenomatoid hamartoma

Sinonasal respiratory epithelial adenomatoid hamartoma (REAH) is a rare benign glandular proliferation of the sinonasal cavities. It is most commonly encountered within the olfactory clefts.

Epidemiology

It is most often encountered in middle-aged adults with no definite gender predilection ^1,2.

Clinical presentation

Clinical presentation is nonspecific with symptoms related to obstruction of the sinonasal cavities ². The most common symptoms include nasal airway obstruction (~60%), hyposmia (~18%), facial pain (~14%), rhinorrhea ( ~14%), and postnasal drip ( ~8%) ².

Pathology

It is a benign, non-neoplastic, inflammatory polypoid lesion lined with ciliated respiratory epithelium most commonly found in the olfactory clefts or posterior nasal cavities with nasopharyngeal extensions ^1,2.

There is some controversy as to whether it represents an isolated (REAH_i) or an incidental pathologic finding as it is often encountered with sinonasal polyposis (~70%, REAH_snp) ¹. It has also been described in association with inverted papilloma and low-grade sinonasal adenocarcinoma ¹. As such, its clinical significance, especially when coexisting with sinonasal polyposis, is uncertain. 

Radiographic features

REAH_i is described as a hypoattenuating homogeneous mass arising from and widening the olfactory clefts that mimic other solitary polypoid sinonasal lesion ^1,2.

REAH_snp is difficult to distinguish from sinonasal polyposis, but the widening of the olfactory clefts (> 10 mm) should raise suspicion.

In one series, REAH has been described as bilateral in up to ~40% of cases ².

History and etymology

It was first described as a distinct entity in 1995 by Wenig and Heffner ³.

Differential diagnosis

General differentials consideration include:

• sinonasal polyposis (REAH_snp) and inflammatory polyp (REAH_i)
• esthesioneuroblastoma: associated with a skull-base defect
• encephalocele: associated with a skull-base defect 
• sinonasal adenocarcinoma