A rare case of a sebaceous nevus in the external auditory canal. (Original Article).

Abstract

We report the case of a patient who came to us for evaluation of a progressive unilateral hearing loss and who was found to have a sebaceous nevus in an unusual location. the external auditory canal. A sebaceous nevus is a congenital organoid mass that occurs primarily on the face, scalp, and periauricular regions. Despite the predilection of sebaceous nevi for the head and neck, reports of this lesion rarely appear in the otolaryngology literature. Left untreated, the lesion can progress through three stages of gross and histopathologic development; a sebaceous nevus begins as a small benign papule, grows into an enlarging mass with different characteristics, and ultimately becomes a secondary neoplasm. The lesion's potential for malignant transformation and its association with syndromes underscores the importance of prompt recognition and appropriate management. This case report adds the sebaceous nevus to the differential diagnosis of external auditory canal lesions and provides essential information abou t this rare mass.

Introduction

Jadassohn in 1895 described organoid nevi as localized, congenital skin lesions that contain an excess of glandular and epidermal structures. (1) He specifically discussed the sebaceous gland nevus, a type of organoid nevus that is made up almost entirely of a disproportionately high number of large, well-formed sebaceous lobules. In 1932, Robinson reported four cases of organoid nevi that were characterized by papillomatous epidermal hyperplasia and numerous excessively large sebaceous glands. (2) These nevi were all located on the face and scalp, and one of them developed into a secondary neoplasm.

Since then, the term nevus sebaceus of Jadassohn has been used to refer to a syndrome characterized by congenital organoid nevi and an excessive number of sebaceous glands that are generally located on the head and neck. A number of reports have described the transformation of sebaceous nevi into secondary neoplasms and their association with syndromes. In this article, we report the case of a patient who had a recent onset of left-sided hearing loss secondary to the growth of a left external auditory canal mass that was identified as a sebaceous nevus.

Case report

A 22-year-old white man came to us for evaluation of a progressive hearing loss on the left. The only pertinent aspect of his otologic history was the presence of a small, asymptomatic, left external auditory canal mass that had been first noticed on physical examination 2 years earlier. No diagnostic work-up or treatment was initiated at that time.

Findings on our physical examination of the head and neck were unremarkable except for the condition of the left ear, which was marked by a significant cerumen impaction. Following removal of the cerumen, the patient's hearing was subjectively restored to its baseline level. Otomicroscopic examination revealed the presence of a large, violaceous, polypoid mass that was anchored superiorly and that almost completely occluded the external auditory canal (figure 1). The growth extended from the lateral external auditory canal to near the tympanic membrane. The mass was compressible, which allowed for visualization of an intact tympanic membrane and normal middle ear space. The lesion was mildly tender to palpation.

Findings on preoperative audiometry were within normal limits. Computed tomography (CT) demonstrated that an irregular, slightly lobular soft-tissue mass had lined the superior portion of the left external auditory canal (figure 2). The mass was adjacent to but did not penetrate the tympanic membrane, nor did it invade the middle ear, mastoid, or cranial fossa. No bone erosion or soft-tissue expansion was observed.

The patient was taken to the operating room for excisional biopsy. The base of the mass occupied the entire superior external auditory canal, from the junction of the concha auricularis to the tympanic annulus. Complete excision with adequate margins was performed, leaving a small area of exposed bone that was partially covered with local skin flaps and then allowed to heal by secondary intention. Packing was placed in the ear canal for 1 month to prevent stenosis.

Gross pathologic examination of the mass revealed multiple brown tissue fragments that measured 1.5 x 1.3 x 0.5 cm in aggregate. Histopathologic study identified a papillomatous hyperplasia of the hyperkeratotic surface epithelium and a large number of underlying mature sebaceous glands, keratin-filled infundibula, small hair structures, and deep apocrine glands (figure 3). These findings were consistent with a diagnosis of a sebaceous nevus. At 2 years of follow-up, the patient showed no evidence of recurrence.

Discussion

The incidence of sebaceous nevi is approximately 0.68%. (3) In affected patients, these lesions are usually present at birth, although they are often not identified until years later or until they become symptomatic. They are equally common among males and females, and they have no racial or ethnic predilection. These nevi arise almost exclusively on the face, scalp, and periauricular area, and their size ranges from 5 mm to 8 cm. Most of these lesions are round or ovoid; the approximately 15% that are linear might be associated with linear sebaceous nevus syndrome. (3,4)

Stages of development. Mehregan and Pinkus examined 150 cases of sebaceous nevi, and in 1965 they became the first to describe the three phases of development. (4) Their report was the first to document the natural course of sebaceous nevi and their potential to develop into secondary neoplasms.

In their first stage, sebaceous nevi are generally found in children (from birth to prepuberty). These lesions appear as a smooth, waxy, thick, yellow-orange papules or plaques accompanied by local alopecia. Histologically, first-stage sebaceous nevi are characterized by papillomatous epidermal hyperplasia, hypergranulosis, hyperkeratosis, and increased numbers of prickle cells. (4,5) Numerous small, underdeveloped lobules are associated with abnormally developed and immature hair follicles. Most specimens feature a thick dermis that is marked by increased vascularity and prolific fibrous connective tissue. (4)

The second phase usually begins around the time of puberty, and the progression to the new stage can become grossly apparent with the onset of changes in the color, size, and/or shape of the nevus. The color often changes from yellow-orange to purple or dark brown. Second-stage nevi can be verrucous or linear, and they can project an uneven or nodular appearance. Again, the nevus is either completely devoid of hair or nearly so. It will often feel firm or rubbery on palpation. Histologically, the papillomatous epidermal hyperplasia becomes more pronounced in the second phase. The well-developed sebaceous glands increase in size and number, and an abnormally high number of them arise in the dermis. (3) The number of apocrine glands also increases, and they can become cystic or hyperplastic. (4)

Not every sebaceous nevus advances to the third stage, which is characterized by the transformation of skin appendages into secondary neoplasms--namely, papilliferous syringadenomas and basal cell carcinomas. Of the 52 tumors found in sebaceous nevi in the Mehregan and Pinkus study, 21 were basal cell epitheliomas, eight were papilliferous syringadenomas, and six were hidradenomas. (4)

These findings prompted a change in the standard management of sebaceous nevi to include early and complete excision to preclude the development of neoplastic transformation.

Secondary neoplasms. Between 10 and 30% of sebaceous nevi become secondary neoplasms. (3, 4) Jones and Heyl studied 140 cases of sebaceous nevi and found that nearly 20% transformed into papilliferous syringadenomas. They also found that the incidence of basal cell carcinoma was less than half the rate that had been reported by Mehregan and Pinkus (6 and 14%, respectively). (3, 4) This difference might be attributable to Jones and Heyl's exclusion of specimens that exhibited "balaloid proliferation" but that had not yet demonstrated any malignant characteristics. In a recent article, Misago et al wrote that many basal cell carcinomas that have been reported to have arisen from sebaceous nevi were actually trichoblastomas. (6) They suggested that the incidence of basal cell carcinoma secondary to sebaceous nevi is actually lower than what has been reported in previous studies. (6) But regardless of the actual incidence of basal cell carcinomas, it has no effect on the management of sebaceous nevi because thei r neoplastic potential necessitates prompt, complete excision and long-term follow up.

Another feature of sebaceous nevi is the development of multiple different secondary neoplasms within the same lesion. Mehregan and Pinkus reported that of the 33 patients in their study who had secondary neoplasms, 13 had two or more types of tumors. (4) Marlowe and Cron reported a sebaceous nevus that transformed into three distinct neoplasms: an intradermal nevus, a trichoepithelioma, and a basal cell carcinoma. (7) Other authors have reported multiple foci of a basal cell carcinoma, (8) sebaceous carcinoma, trichoblastoma, sebaceoma, and superficial trichoblastoma. (6) Fortunately, most secondary neoplasms are benign, slowly growing lesions, and there are few reported cases of recurrence and metastasis. (9)

Syndromes. Two syndromes associated with sebaceous nevi have profound manifestations. Although they are rare, they should be considered in the work-up of patients who have sebaceous nevi. They are linear sebaceous nevus syndrome and phacomatosis pigmentokeratotica.

Linear sebaceous nevus syndrome. In 1962, Feuerstein and Mims described two patients who had a triad of findings: linear sebaceous nevi, seizures, and mental retardation. (10) More reports of similar findings and additional variants soon followed, suggesting that linear sebaceous nevus syndrome usually occurs as a forme fruste of the entire syndrome. These variants include, but are not limited to, eye abnormalities (e.g., colobomas, choristomas, and ectopic lacrimal gland tissue), cardiovascular anomalies (e.g., patent ductus arteriosus and ventricular septal defects), hemimegalencephaly, facial hemihypertrophy, renal malformations (e.g., nodulocystic and/or hypotrophic kidneys), syndactyly, skeletal abnormalities, cleft lip and palate, and other skin lesions (e.g., hemangiomas and lipomas). (11-13)

Phacomatosis pigmentokeratotica. Phacomatosis pigmentokeratotica is characterized by several conditions: a sebaceous nevus, a speckled lentiginous nevus in a checkerboard pattern, hemiatrophy with muscular weakness and other neurologic abnormalities (e.g., hyperreflexia, segmental hyperhidrosis, and dysesthesia), mental retardation, seizures, deafness, ptosis, and strabismus. (14) This syndrome is distinctly different from linear sebaceous nevus syndrome. Patients do not exhibit eye colobomas or lipodermoids.

Management. The management of sebaceous nevi is hardly controversial given their potential to transform into secondary neoplasms. Even though prepubertal patients are at low risk for secondary neoplasms, the second phase, which occurs around the time of puberty, is marked by the lesion's rapid expansion and increased depth. Ideally, sebaceous nevi should be removed while they are still in the first stage to ensure ease of excision and to minimize scar formation. Dermabrasion and laser photo-coagulation are inadequate for removing sebaceous nevi; these methods are associated with recurrence, hypertrophic scarring, and the induction of secondary neoplasms as a result of incomplete removal. For linear sebaceous nevi, serial excision with tissue expanders has resulted in satisfying outcomes. (5)

The significance of our case report is twofold. First, it familiarizes otolaryngologists with the sebaceous nevus and its pathology, management, and association with secondary neoplasms and syndromes. Second, it extends the differential diagnosis of external auditory canal masses (table) to include sebaceous nevi. Even though these lesions occur almost exclusively on the head and neck, few reports appear in the otolaryngology literature--partly because sebaceous nevi are rare, but also because their management does not necessitate the services of an otolaryngologist. In our patient, however, the location of the nevus and the secondary hearing loss resulted in an otolaryngology consult.

An increased familiarity with sebaceous nevi and their various stages expands the differential diagnosis of not only facial and scalp lesions, but external auditory canal masses as well. Our case represents a classic example of a sebaceous nevus in the second phase of development. It was a purple polypoid mass and it was associated with increased cerumen production that was consistent with the hypertrophic sebaceous glands and the presence of apocrine glands. Despite the typical appearance of this nevus, it was low on the list of differential diagnoses in view of its rarity, its unusual initial sign (hearing loss), and its location deep in the external auditory canal.

When a sebaceous nevus is suspected or identified, the otolaryngolosit who is aware of its association with syndromes and secondary neoplasms should initiate a thorough work-up, which can include ophthalmology, dermatology, and neurology consultations, an audiologic evaluation, and CT of the head. Finally, these patients should undergo long-term follow-up and screening for recurrence and neoplasms.

Table 1

Benign and malignant conditions of the external auditory canal

Benign                  Malignant

Cholesteatoma           Basal cell carcinoma
Eosinophilic granuloma  Ceruminous gland tumor
Exostosis               Melanoma
Fibrous dysplasia       Metastatic disease
Keratosis obturans      Soft-tissue sarcoma (children)
Neurofibroma            Squamous cell carcinoma
Osteoma
Paraganglioma
Stenosis
Temporomandibular
 joint hemiation

References

(1.) Jadassohn J. Bemerkungen zur Histologie der systematisierten Naevi und uber "Talgdrusen-Naevi." Arch Dermatol Syph 1895;33:355-94.

(2.) Robinson SS. Naevus sebaceous (Jadassohn). Arch Dermatol Syph 1932;26:663-70.

(3.) Jones EW, Heyl T. Naevus sebaceus. A report of 140 cases with special regard to the development of secondary malignant tumours. Br J Dermatol 1970;82:99-117.

(4.) Mehregan AH, Pinkus H. Life history of organoid nevi. Arch Dermatol 1965;91:574-88.

(5.) Hagan WE. Nevus sebaceus of Jadassohn: The head and neck manifestations. Laryngoscope 1987;97(8 Pt 1):909-14.

(6.) Misago N, Kodera H, Narisawa Y. Sebaceous carcinoma, trichoblastoma, and sebaceoma with features of trichoblastoma in nevus sebaceus. Am J Dermatopathol 2001;23:456-62.

(7.) Marlowe FI, Cron C. Linear nevus sebaccous of Jadassohn. Laryngoscope 1979;89:666-70.

(8.) Baker BB, Imber RJ, Templer JW. Nevus sebaceous of Jadassohn. Arch Otolaryngol 1975;101:515-6.

(9.) Tarkhan II, Domingo J. Metastasizing eccrine porocarcinoma developing in a sebaceous nevus of Jadassohn. Report of a case. Arch Dermatol 1985;121:413-5.

(10.) Feuerstein RC, Mims LC. Linear nevus sebaceus with convulsions and mental retardation. Am J Dis Child 1962;104:675-9.

(11.) Lansky LL, Funderburk S, Cuppage FE, et al. Linear sebaceous nevus syndrome. A hamartoma variant. Am J Dis Child 1972;123:587-90.

(12.) Palazzi P, Artese O, Paolini A, et al. Linear sebaceous nevus syndrome: Report of a patient with unusual associated abnormalities. Pediatr Dermatol 1996;13:22-4.

(13.) Shields JA, Shields CL, Eagle RC Jr., et al. Ocular manifestations of the organoid nevus syndrome. Ophthalmology 1997;104:549-57.

(14.) Tadini G, Restano L, Gonzales-Perez R, et al. Phacomatosis pigmentokeratotica: Report of new cases and further delineation of the syndrome. Arch Dermatol 1998;134:333-7.

From the Department of Otolaryngology-Head and Neck Surgery, Madigan Army Medical Center, Fort Lewis, Tacoma, Wash.

Reprint requests: Nici Eddy Bothwell, MD, 903 148th St., Court East, Tacoma, WA 98445. Phone: [phone]; fax: [phone]; e-mail: [e-mail]