Cutaneous lesions of the external ear
© Sand et al. 2008
Received: 27 September 2007
Accepted: 08 February 2008
Published: 08 February 2008
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© Sand et al. 2008
Received: 27 September 2007
Accepted: 08 February 2008
Published: 08 February 2008
Skin diseases on the external aspect of the ear are seen in a variety of medical disciplines. Dermatologists, othorhinolaryngologists, general practitioners, general and plastic surgeons are regularly consulted regarding cutaneous lesions on the ear.
This article will focus on those diseases wherefore surgery or laser therapy is considered as a possible treatment option or which are potentially subject to surgical evaluation.
When evaluating skin lesions on the ear, specific anatomical peculiarities should be considered. The outer ear consists of the skin bearing external ear canal and the auricle. Both are of elastic cartilage covered with skin. It is attached to the periost and poorly vascularised. The epidermis on the concave aspect lies on a very thin subcutis which is strongly attached to the auricular cartilage. In contrast the convex aspect of the outer ear has a thicker subcutis with a stronger layer of subcutaneous fat which causes a certain laxity and displaceability compared to the concave side. An additional anatomical uniqueness is the high concentration of holocrine ceruminal glands in the skin of the external ear canal. The cerumen may mask existing diseases of the skin in the entrance of the external ear canal. In case of a ceruminal obstruction, an adequate assessment of the external auditory meatus should be done only after cleaning, which may demask existing dermatosis. The auricle is susceptible to environmental influences and trauma. Because of its exposed localization, the ear is particularly liable to the effects of ultraviolet (UV) light and, consequently, to pre-neoplastic and neoplastic skin lesions. Further, it has a sound-transmitting function and is located at a visible, esthetically obvious site, drawing considerable attention from the patient. Depending on the localization, lesions on the external ear which lead the patient to seek professional help are noticed by the patient himself or by a relative or friend.
When hidden areas of the outer ear are affected, consultation may be delayed until very late in the disease process. This is especially true for malignant tumors which may often present at an invasive stage, due to the minimal thickness of the skin compared to other parts of the body. In many cases, optimal medical care for patients with skin diseases of the external ear requires an interdisciplinary approach dermatological, ear-nose-throat and surgical collaboration. Below, the most important and frequent skin diseases of the ear which are potentially subject to surgical or laser therapy are described. Because of the large number of different diagnosis a description of all pathologic conditions of the external ear seems to be impossible. Hence, we limited our description to the diseases which are frequent or call for special attention because of their prognosis.
Atheroma is a benign tumor which is mostly located at the back of the earlobe. On clinical exam, it appears as a 5 – 25 mm firm, displaceable nodule and may show signs of secondary infection. Sometimes, a pinpoint depression at the surface of the cyst corresponds to the infundibulum of a pre-existing hair follicle. The high density of sebaceous glands over the earlobe predisposes the ear for this lesion. Therapy consists of spindle-shaped excision to prevent recurrence. Other techniques of removal include punch biopsy aspiration followed by curettage and avulsion of the cyst wall. Cysts removed from the back of the ears have the highest recurrence rates (13% and 13.8%) . Regardless of the chosen treatment, thorough removal of the cyst wall seems therefore to be essential for reducing the high recurrence rates.
Actinic keratoses is a UV light-induced lesion which is often located on the ear, especially on the helical rim. Its frequency increases with age and can progress to invasive squamous cell carcinoma in 20%, a malignant transformation which treatment can prevent . Its prevalence is higher in individuals with fair complexion. Mostly, a well-defined patch with a rough texture, 3–8 mm in diameter, and typical erythematous base is visible, accompanied by occasional hyperkeratosis. However the lesion may grow to large hyperkeratotic plaques with several centimeters in diameter. Signs of inflammation may occur. In the case of a persistent, recurrent, or isolated lesion, a biopsy is recommended to confirm the diagnosis . Effective treatment options are curettage, photodynamic therapy, laser therapy, topical 5-floururacil (5-FU), diclofenac, colchicine, imiquimod and retinoid application [10–13].
Cutaneous Horn is not a pathological diagnosis. A variety of primary underlying processes, benign, premalignant or malignant, can cause this lesion [14–17]. It presents a mostly asymptomatic, variably sized, keratotic mass arising from the superficial layers of the skin or deeply from the cutis . It generally occurs on sites, which are subjected to actinic radiation, with the upper part of the face and the ears being the most common area . In a case series of 643 cutaneous horns, 40% were derived from malignant or premalignant epidermal lesions (squamos cell carcinoma, actinic keratosis), and 60% from benign lesions . The important issue when dealing with this lesion is accurate determination of the nature of the processes at its base. An underlying lesion with malignant or premalignant potential at the base of a cutaneous horn is a common finding wherefore we recommend excision and histology.
The most successful therapy for basal cell carcinoma is micrographic-controlled surgery (two stage operation). Five-year recurrence rates by micrographic-controlled surgery are reported to be between 1 and 5.6% [21, 22]. Nevertheless, BCC found in the middle of the face (so-called H-zone), followed by those on the auricular and preauricular area have the highest rate of recurrence following treatment by excisional surgery, radiation, cryosurgery, curettage or electrodessication – all alternative forms of treatment [23–25]. Several theories attempt to explain the high rate of relapse. The ear has a complex anatomy which can confuse the assessment of tumor boundaries . Further an unusual horizontal growth phase makes this tumor prone to incomplete excision . As mentioned above, the skin on the concave aspect of the outer ear is very thin and close to the perichondrium. This encourages subclinical spread  as skin cancers grow both radially and vertically. Additionally numerous embryonic fusion planes in the auricular skin have been suggested that may contribute to the spread of the tumor . Pensak has described cartilaginous fissures (Santorini) in the lateral floor of the ear canal and a bony dehiscence (Huschke's Foramen) in the medial floor of the ear canal to provide pathways for intracranial tumor spread which also have to be considered . In cases of growth into the parotid gland, a lateral parotidectomy with monitoring of the facial nerve has to be performed. Closure of skin defects can be achieved by local flaps in most patients.
Bowens disease is an intraepidermal carcinoma in situ, presenting the preinvasive form of squamous cell carcinoma. It is strongly associated with sun exposure and lesions are in up to 83% infected with human papillomavirus (HPV) type 16 . The lesions are erythematous, scaly patches or plaques with irregular borders which can occur anywhere on the skin. They can become hyperkeratotic, crusted, fissured, or ulcerated and generally occur in sun-exposed areas. On the ear, they are most frequently found on the helical rim or the external side of the auricle. Although the size is variable, Nordin et al. describe a mean size on the ear of 18 mm (range 5–70 mm) . Bowens disease is a carcinoma in situ of the epidermis and therefore potentially malignant. Progression to invasive SCC is noted in approximately 10% of Bowen's lesions. It should therefore be completely excised when possible by means of micrographic guided surgery.
Histological the atypical and disordered keratinocytes in bowens disease extend down the follicular epithelium. Superficial, topical treatment is therefore associated with an increased probability of recurrence.
Topical imiquimod, 5-FU, cryotherapy, photodynamic therapy, x-ray and grenz-ray radiation, cauterization or diathermy coagulation therapy are described to be effective but lack mircrographic control [31–33]. The latter forms of treatment can be considered for large lesions which are sometimes spread over the whole ear or for patients who refuse surgery.
SCC lesions on the nose and ear have the highest rates of recurrence which might be due to an association with embryonic fusion planes . Therapy should therefore be aggressive as tendency of recurrence is high . A complete excision by means of micrographic surgery with tumor free margins is necessary for a successful outcome and should be attempted whenever possible. Although this tumor tends to grow in a vertical fashion it is less likely to respect the barriers of cartilage and bone than BCC. Consequently intratemporal spread with involvement of the external auditory canal is possible and can lead to conductive hearing loss. With further deep extension facial nerve palsy due to destruction of the facial nerve along its vertical or tympanic segment may evolve, and finally a further advancement into the internal auditory canal and cerebellopontine angle may cause dizziness and/or sensorineural hearing loss.
Additionally it is important to investigate for possible regional lymph node metastases which portends poor prognosis. Locoregional metastases follow the lymphatic drainage patterns which include the parotid and upper cervical nodes [38, 39]. Nodal involvement is reported to be present in 1–12.5% of all cases [40–42]. Therapy for locoregional metastases is regional lymphadenectomy (Neck-dissection level I-V), followed by postoperative irradiation. It has been suggested that with evidence of lymphovascular or perineural spread in the primary specimen the nearest "sentinel node" should be examined. In cases of histologically aggressive malignancy prophylactic lymphadenectomy and/or regional irradiation should be considered [43, 44]. However large multi-institutional studies are missing, therefore the role of sentinel lymph node biopsy for SCC of the head and face region can not be determined so far.
Lentigo maligna (LM) is a slow-growing, non-invasive melanoma in situ. Little attention is paid to this insidious lesion which can potentially become an invasive lentigo maligna melanoma with a conversion rate of 33–50% . The estimated lifetime risk of LM progressing to LM melanoma is 5% . The lesion begins as an unevenly pigmented and irregularly bordered, brown to black macule which slowly extends in the course of time. The lesions size can sometimes obtain several centimetres. It begins as a tan macule which extends peripherally within the course of several years. Non-surgical therapy such as cryosurgery, radiotherapy, electrodessication and curettage, laser surgery, and topical medications with a recurrence rate ranging from 20 to 100% at 5 years have been described in the literature. Recurrence following standard therapies is common because histologic evaluation can be difficult due to the widespread atypical melanocytes that are present in the background of long-standing sun damage . Whenever excision by means of micrographic-controlled or MOHS surgery is possible it should be the preferred method of treatment as it shows the lowest recurrence rate (4–5%) and the best form of margin control among all described forms of therapy. As this lesion occurs more frequently in an elderly patient population, alternative forms of treatment, such as radiotherapy, have to be considered when patients present with very large lesions that are not subject to reconstructive surgery.
Approximately twenty percent of all primary melanomas are located at the head and neck, of which 7–14% are located at the ear's helix and antihelix. Peripheral parts of the ear are more frequently affected. Interestingly the left ear is more often affected than the right ear. The most accepted theory for this phenomenon is the asymetric UV-dosage in anglo-saxon countries with left-hand driven cars. Further, a male predisposition of 61.5–90.5% is reported in the literature with a predisposition for fair-skinned individuals [61–66]. It can be explained with different hair styles which correlate with UV exposition. With the exception of young children this disease affects all age groups. The average age is 50 years.
The available data for sentinel node sampling do not permit definitive conclusions regarding a prognostic or even therapeutic impact of sentinel lymph node biopsy (SLNB) in patients with melanoma of the ear. Patients with tumours thicker than 1 mm are currently undergoing SLNB and should be included in large multicenter studies. In special cases where surgical removal of a lentigo maligna melanoma is not possible, radiation therapy should be considered as an alternative with good results . Unfortunately this tumor is aggressive, with a tendency for spreading to both regional lymph nodes and distant sites. One third of all patients presenting with auricular melanoma have cervical lymph node involvement. As the correlation between melanoma location and drainage is inconsistent lymphoscintigraphy with sentinel node sampling seems to be the primary method of identifying nodal disease [70, 71]. However a final evaluation is not possible. Adjuvant therapy includes chemotherapy, immunotherapy, and radiation.
Infectious lesions of the external ear are rarely subject to surgical intervention. Nevertheless drainage of the subperichondral space and surgical removal of necrotic ear tissue following infectious diseases of the external ear are sometimes necessary.
As the skin of the external auditory canal shows a high concentration of ceruminal glands it is susceptible for this already very rare type of benign and malignant tumours. Benign adnexal tumours include ceruminous adenomas and pleomorphic adenoma which are best treated by wide local excision . Malignant adnexal tumours include adenoidcystic-, mucinous-, cylindro-, poro-, spiradeno and adenocarcinoma [79–81]. They should be treated by an initial aggressive wide en bloc surgical resection with a primary lateral or subtotal temporal bone resection stage dependent combined with a parotidectomy and neck dissection. Even in T1 tumours local resection is described to be not sufficient . However due to their rarity, a further discussion of these individual tumors is beyond the scope of this article.
The outer ear with the auricle and ear canal can be affected by a variety of different skin lesions and dermatologic conditions. They can be either solitary lesions which are locally limited to the ear or are part of a generalized dermatologic condition. They can afflict skin, cartilage, glands, vessels and hair follicles of the outer ear.
The outer ear itself plays a functional role in audition by collecting and transmitting sound. Additionally it has an important effect on facial appearance and therefore on the individual psychological disposition. Although the auricles skin macroscopically shares the anatomy and physiology of the bodys skin it shows some histological differences compared to the rest of the bodys skin. This specific anatomical peculiarities should be considered when treating skin lesions on the ear.
In cloncusion, the authors suggest that an interdisciplinary approach that combines surgery, dermatology and otolaryngology can provide optimal care for the patient. The most common skin diseases of the outer ear which are potentially subject of surgical or laser therapy have been described briefly in this review.
The written consent was obtained from the patients.
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