Nasopharyngeal Respiratory Epithelial Adenomatoid Hamartoma—Master of Masquerade

Introduction

Respiratory Epithelial Adenomatoid Hamartoma (REAH) is a benign non-neoplastic lesion occurring in the nasal cavity, paranasal sinuses and nasopharynx which is described as “a proliferation of glands lined by multi-layered ciliated respiratory epithelium, often with admixed mucocytes, arising in direct continuity with the surface epithelium, which invaginate downward into the submucosa. ¹ Hamartomas were first described by Albrecht in 1904, as benign overgrowth of tissues which are native to a particular area of the body, which grow in a haphazard manner. ² This is in contrast to choristomas which are overgrowth of tissues not native to that particular area of the body. REAH is a condition that was first described by Wenig and Heffner in 1995 after an analysis of 31 cases. Herein, we discuss a case of a female patient who presented with a chronic history of nasal block and symptoms of chronic sinusitis, with endoscopic evidence of nasal polyps that extended into the nasopharynx which were removed during surgery after a thorough initial investigation. Final histopathological diagnosis after excision of the polyps was that of a REAH.

Case Report

A 67-year-old lady presented with a chronic history of nasal block for 14 years. The nasal block was bilateral and associated with hyposmia. Her symptoms were worsening in the 3 months preceding her surgery in which she had facial pain, thick mucoid nasal discharge and post nasal drip associated with persistent cough not relieved with steroid nasal spray, antihistamines and nasal douching.

She has a background history of follicular thyroid carcinoma 40 years ago which was treated by surgery and radioactive iodine, and endometrial carcinoma 8 years ago which was treated by surgery, both of which showed no evidence of recurrence with regular surveillance. She is also a diabetic on treatment.

On examination there was no obvious nasal deformity, facial tenderness, or facial numbness. No cervical lymphadenopathy and cranial nerve examination was normal. Endoscopic nasal examination revealed bilateral pale polypoidal tissue arising from the middle and superior meatus with extension posteriorly into the nasopharynx.

CT scan (Figure 1) of the paranasal sinuses showed mucosal thickening within the maxillary, ethmoid, and sphenoid sinuses with extension of a soft tissue mass into the nasopharynx. She underwent a bilateral functional endoscopic sinus surgery with excision of the polypoidal mass. Intra operatively, there was multiple nasal polyps arising from bilateral maxillary, ethmoid and sphenoid sinuses. Polypoidal tissue growth extended posteriorly into the nasopharynx and there was mucoid and pus discharge from the right maxillary sinus.

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Figure 1.

CT scan images showing the lesion (blue cross arrow) within the nasopharynx.

The histopathology laboratory received fragments of reddish brownish tissues measuring 1.5 cm in total. Microscopy (Figures 2 and 3) shows polypoidal fibro-vascular tissues partly covered by respiratory type epithelium, exhibiting focal areas of stromal oedema, and moderately infiltrated by mixed inflammatory cells—predominantly plasma cells, lymphocytes and few neutrophils. There are scattered subepithelial cystic structures that resemble invaginated ciliated respiratory type epithelium. The basement membranes of these cysts and surface epithelium appear thickened. Proliferating lobules of sero-mucinous glands, some of which are dilated with intraluminal inflammatory secretions, are present within vascularized and collagenous stroma.

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Figure 2.

Inflamed polypoidal tissue with invaginated cysts (V) and thickened basement membrane (B). [Hematoxylin & Eosin, original magnification x2].

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Figure 3.

Focal areas of the polyp show proliferating lobules of sero-mucinous glands. [Hematoxylin & Eosin, original magnification x2].

Post operatively she has been seen in the outpatient clinic 3 times over a period of 5 months and during each review the endoscopic examination carried out showed no evidence of polyp recurrence.

Discussion

REAH is a sinonasal benign tumor characterized by glandular proliferation of the epithelium lining the nasal cavity and sinuses. ³ Sinonasal hamartomas are uncommon and the majority of hamartomas occurring in this region are of the pure epithelial type with mesenchymal or mixed types occurring rarely. The etiology of this lesion is unknown with no associations with any specific agents such as tobacco, smoking, occupational or environmental exposure. However, the possibility of inflammation in the initiation of REAH remains the most plausible risk association as REAH mainly occurs in the setting of inflammatory polyps. ¹

Mean age presentation is at the fifth to sixth decades of life. ⁴ The symptoms of REAH are non-specific and include nasal block, hyposmia, epistaxis, facial pain and it normally occurs along with nasal polyposis rather than in isolation. Most case series and studies have described a male predominance. In Wenig and Heffner’s study of 31 patients, the ratio of males to females was 7:1. In a review of 12 articles with a total of 44 patients by Fitzhugh et al the ratio was 4:1. And most recently by Nguyen et al a review of 325 patients yielded a ratio of 3:2.^1,4,5

On endoscopic nasal examination, REAH usually presents as a polypoidal fleshy mass within the nasal cavity. In the initial reviews, REAH was described to occur in the nasal cavity with a predilection to the posterior nasal septum. In recent reviews, it is apparent that the lesions arise more commonly at the olfactory cleft.^4,6 Lesions in the nasopharynx are still rarely described in the literature and in most cases, a more sinister diagnosis was initially suspected in lesions which extended into the nasopharynx, especially in patients who had significant other comorbid diseases.^3,7,8 Of the 394 cases included in a review by Nguyen et al there was only one case described to occur in the nasopharynx. ⁴

REAH is a condition which is difficult to diagnose based on clinical or radiological features. It may be suspected by an experienced clinician from its firmer consistency in comparison to the inflammatory polyp. A definitive diagnosis can be made by histopathological examination of the tissue. Grossly the tissue is described as a polypoidal or exophytic mass with a rubbery consistency that is tan-white to red-brown. The histopathological findings include the presence of a multi-layered ciliated respiratory epithelium admixed with mucin-secreting Goblet cells, with medium to large glandular formation. The glands are separated by stromal tissue which connect to the surface and in some areas the glands may invaginate down into the submucosa. The stroma is edematous with a mixed chronic inflammatory cell infiltrate. The presence of stromal hyalinization with envelopment of glands by a thickened eosinophilic basement membrane is characteristic of REAH.^5,9

Differential diagnoses include inverted papilloma, inflammatory polyps, and low grade adenocarcinoma. ¹⁰ In the case of inverted papilloma and adenocarcinoma, a simple resection will not suffice and more extensive management is required. Therefore, distinguishing the more sinister pathologies are of utmost importance in managing patients. The main difference between REAH and the more sinister pathologies will be the non-invasive nature of REAH which is evident from clinical examination and imaging. Extension of disease beyond the nasal cavity or presence of bony erosion does not occur in REAH. Histopathological examination of inverted papilloma shows invagination of proliferating stratified squamous cell epithelium with mild to moderate atypia. In low grade adenocarcinoma, differentiation from REAH may be more challenging especially if the specimen is submitted as a small biopsy specimen. Some distinguishing features proposed by Sangoi and Berry to support the diagnosis of REAH include the absence of cribriform architecture, nuclear dysplasia and increased mitotic figures, with the presence of eosinophilic basement membranes surrounding individual glands, and expanded mucin filled glands lined by ciliated epithelium.^9,11

The treatment of REAH is surgical excision of the lesion. More extensive surgery is not required as it is a benign lesion. Recurrence is also rare following simple excision as documented by most authors and there is no evidence that malignant transformation occurs.^4,9

Conclusion

Sinonasal hamartomas, namely REAH are uncommon lesions. The site of occurrence of this lesion within the nasopharynx also a rare presentation of the disease and especially in a female. Many a time the nasopharyngeal mass is often thought to be a more ominous pathology until proven otherwise. And in the management of a sinonasal mass, especially with extension or origin within the nasopharynx, a high index of suspicion is necessary by the clinician to avoid missing a more ominous pathology. The treatment of REAH is simple excision and recurrence is rare.