Hamartomas are tumor-like but non-neoplastic, malformation or inborn errors of tissue development, characterized by an abnormal mixture of indigenous tissue with an excess of one or more of Indigenous tissue (1).
Respiratory epithelial adenomatoid hamartoma is an uncommon lesion of the upper aerodigestive tract (2). It is characterized by abnormal glandular formations with ciliated epithelium arising from the nasal cavity, paranasal sinuses and nasopharynx (3), but other locations have also been described (2).
We did not find any other cases of this hamartomas in the external auditory canal in the literature.
A 40-year-old man was referred to the otorhinolaryngology department due to otorrhea and decreased hearing from 1 year ago.
Otoscopic examination showed a reddish hemorrhagic mass in the left external auditory canal, without otitis sings. Intraoperatively, the tumor was completely resected.
Histological examinations showed a polypoid lesion composed of numerous glands lined by several layers of bland ciliated respiratory epithelium and surrounded by a thick collagenized basement membrane (Figures 1 and 2). The glands were round to oval and varied in size from small to large and cystically dilated. The glandular lumina contained mucinous or amorphous material (Figure 3). Frequent areas of mucous metaplasia were seen. The stroma was edematous and contained mixed inflammatory cells (Figure 4). The pathologic findings were consistent with REAH.
Fig. 1. The glands are lined by ciliated respiratory epithelium. The nuclei are bland.
Fig. 2. The glands are lined by ciliated respiratory epithelium. The nuclei are bland.
Fig. 3. The dilated glands, containing mucinous or amorphous material.
Fig. 4. Polypoid appearance with numerous glands and inflamed stroma
Respiratory epithelial adenomatoid hamartoma (REAH) was first reported in a series of 31 cases by Wening and Heffner in 1995 (4). Approximately 70% of REAH present in the nasal cavity, especially in the posterior part of nasal septum. Besides, nasopharynx, ethmoid, frontal and maxillary sinuses could be involved (3). Until now, no case was reported in the external auditory canal.
Grossly, REAH is a variable size polypoid rubbery to firm mass with glistening yellow to white cut surface (2). Histologically, it is characterized by submucosal glandular proliferation. The glands are lined by bland-looking ciliated respiratory epithelium and are surrounded by a thick collagenized basement membrane (2). Differentiation of these tumor from other aggressive tumors is important (5).
The main differential diagnosis in external auditory canal are ceruminous adenocarcinoma and adenoid cystic carcinoma (6).
Ceruminous adenocarcinoma, microscopically, characterized by variously sized glandular formations arranged in back to back proliferation and lined by apocrine cells (7). Presence of more than occasional mitotic activity, pleomorphism, the absence of a myoepithelial layer, necrosis and invasiveness are the main diagnostic features (8).
Adenoid cystic carcinoma is diagnosed by pseudocysts and true glandular structures with cribriform pattern. The glands are lined by a monolayer of eosinophilic epithelial cells with scant cytoplasm and hyperchromatic angulated nuclei (9). Perineural invasion is the main diagnostic clue (10).
The other differential diagnosis is inflammatory aural polyp, which is characterized by squamous or ciliated cells epithelium with mixed inflammatory cells infiltrations and granulation tissue formation, but no glandular structures are seen (11).
REAH is an uncommon lesion of the upper aerodigestive tract, but until now, no case was reported in the external auditory canal. The main differential diagnosis in the external auditory canal are ceruminous adenocarcioma and adenoid cystic carcinoma. Therefore, the rule out of this differential diagnosis will aid in determining the best treatment protocol.
The authors would like to express gratitude towards all who helped in the improvement of this paper.
Conflicts of Interest
The authors declared that there is no conflict of interest regarding the publication of this article.