Nevus Sebaceous of External Auditory Canal; Significance of Managing It: A Rare Case Report

Ashwani Sethi¹, Rohit Bhardwaj² https://orcid.org/0000-0003-4005-4719, Deepika Sethi³

^1,2Department of ENT, Army College of Medical Sciences & Base Hospital, Delhi Cantt, Delhi, India

³Department of ENT, Dr. Baba Saheb Ambedkar Medical College & Hospital, Delhi, India

Corresponding Author: Rohit Bhardwaj, Department of ENT, Army College of Medical Sciences & Base Hospital, Delhi Cantt, New Delhi, India, Phone: +91 9871759227, e-mail: drrohitbhardwaj90@gmail.com

Received on: 24 January 2023; Accepted on: 20 April 2023; Published on: 28 June 2023

ABSTRACT

Introduction: Nevus sebaceous is a benign mass lesion occurring primarily on the face, scalp, and periauricular region. The occurrence of this lesion in the external auditory canal is very rare.

Case description: We present a case of nevus sebaceous of the external auditory canal, which was diagnosed with the help of histopathology and treated successfully by surgical excision.

Discussion: The nevus sebaceous is a benign lesion but harbors malignant potential in it, necessitating excision of the lesion with adequate margins in order to avoid recurrence or malignant transformation.

Conclusion: Nevus sebaceous although rare but can arise in the external ear canal and can be managed successfully if excised completely with adequate margins.

How to cite this article: Sethi A, Bhardwaj R, Sethi D. Nevus Sebaceous of External Auditory Canal; Significance of Managing It: A Rare Case Report. J Med Acad 2023;6(1):28-30.

Source of support: Nil

Conflict of interest: None

Patient consent statement: The author(s) have obtained written informed consent from the patient for publication of the case report details and related images.

Keywords: Becker nevus syndrome, Hearing loss, Nevus, Sweat gland neoplasms, Skin neoplasms, Tympanic membrane

CASE SUMMARY

A 35-year-old male presented to us with a painless, gradually progressive mass in the right ear of 2 years duration. There was no history of ear discharge or hearing loss and no history suggestive of any similar lesion elsewhere in the body.

Examination revealed a yellowish-brown, nontender, firm, and polypoidal mass measuring approximately 5 × 5 mm apparently arising from the floor of the external auditory canal just lateral to the bony cartilaginous junction almost completely obliterating the external auditory canal (Fig. 1). The mass was excised with adequate margins and subjected to pathological evaluation. A normal and intact tympanic membrane could be visualized after excision of the mass. Gross pathologic evaluation revealed a single, yellow to dirty brown colored, skin-lined mass measuring 5 × 5 × 7 mm (Fig. 2). Histologically, a low power view [50×, hematoxylin and eosin (H&E) staining] showed a large conglomerate of multiple pilosebaceous units with keratotic plugging (Fig. 3). High power view (250×, H&E staining) showed foci with nests of basaloid cells along with immature hair follicles (Fig. 4). With this histopathological evaluation the final diagnosis of the lesion was given as nevus sebaceous. The patient has been under follow-up for almost 5 years and is free of any recurrence or any other lesion at the site.

Fig. 1: Mass filling the external auditory canal

Fig. 2: Surgically excised mass (nevus sebaceous)

Fig. 3: Microphotograph showing multiple pilosebaceous units with keratotic plugging (50×, H&E)

Fig. 4: Microphotograph showing nests of basaloid cells along with immature hair follicles (250×, H&E)

DISCUSSION

Nevus sebaceous has been described by Jadassohn as a congenital organoid mass that contains an excess of glandular and epidermal structures.¹ It usually presents as a yellow–orange-colored, waxy, pebble-like papule or plaque.² The incidence of this lesion is approximately 0.68% with equal incidence among males and females without any racial predilection.³^,⁴

Nevus sebaceous primarily occurs on the face, scalp, and periauricular region.⁴ The presence of this lesion in the external auditory canal is extremely rare and a review of pertinent English literature revealed only two such cases reported in the past.⁴^,⁵ Most of these lesions are round to ovoid and linear lesions may be associated with syndromes in approximately 15% of the cases.⁴ There are six different epidermal nevus syndromes described so far—Proteus, congenital hemidysplasia with an ichthyosiform nevus and limb defect syndrome, phakomatosis pigmentokeratotica, sebaceous nevus, Becker nevus, and nevus comedonicus.⁶ Although most of these syndromes are associated with disorders of the eye, nervous and musculoskeletal systems, inner ear malformations with hearing loss have also been reported in the past.⁷

These lesions have been classically categorized into three phases of development.⁸ The first phase is found in children till puberty and is characterized by the underdevelopment of hairs and sebaceous glands. The second phase begins at puberty and is characterized by the massive development of sebaceous glands. The third phase is not encountered in all the lesions and is characterized by the development of secondary neoplasms.

Most of the neoplasms developing in nevus sebaceous are benign with trichoblastoma and syringocystadenoma papilliferum as the most common.⁹ Amongst the malignant neoplasms, basal cell carcinoma, sebaceous carcinoma, squamous cell carcinoma, anaplastic adnexal carcinoma, apocrine carcinoma, and porocarcinoma have all been reported in the past.⁹

The diagnosis of this lesion is established on the basis of its characteristic histopathology. The other lesions that may be included in the differential diagnosis of such a mass in the external auditory canal include—eosinophilic granuloma, papilloma, fibrous dysplasia, keratosis obturans, neurofibroma, paraganglioma, ceruminous adenoma, basal cell carcinoma, squamous cell carcinoma, melanoma, and sarcoma.⁴ The management of a nevus sebaceous involves surgical excision with adequate margins followed by a regular follow-up due to the potential of this lesion to develop a secondary neoplasm if not adequately excised.

CONCLUSION

Nevus sebaceous is a benign mass lesion that contains an excess of glandular and epidermal structures. Nevus sebaceous primarily occurs on the face, scalp, and periauricular region with low incidence and without any gender and racial predilection. The occurrence of this lesion in the external auditory canal is very rare. Characteristic histopathological findings help in diagnosing this lesion. Complete surgical excision with adequate margins is the required treatment. Follow-up is crucial due to the chances of developing secondary neoplasm.

ORCID

Rohit Bhardwaj https://orcid.org/0000-0003-4005-4719

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