Background
Pseudocyst of the auricle was first reported by Hartmann in 1846 and first described in the English literature in 1966 by Engel. [1] Historically, pseudocyst of the auricle has been addressed by many terms, including endochondral pseudocyst, intracartilaginous cyst, cystic chondromalacia, and benign idiopathic cystic chondromalacia. Because the condition is uncommon, it may be misdiagnosed or underreported by clinicians. Pseudocyst of the auricle is characterized as a benign, noninflammatory swelling to the ear, located on either the front or side surface. [2, 3]
Pathophysiology
The etiology of pseudocyst of the auricle is unknown, but several pathogenic mechanisms have been proposed.
Originally, Engel postulated that lysosomal enzymes might be released from chondrocytes and cause damage to the auricular cartilage. However, analysis of pseudocyst contents revealed a fluid rich in albumin and acid proteoglycans, with a rich cytokine milieu but lacking in lysosomal enzymes.
Analysis of the cytokine profile of the fluid indicates markedly elevated levels of interleukin (IL)–6, which is believed to stimulate chondrocyte proliferation. IL-1, an important mediator of inflammation and cartilage destruction, induces IL-6. IL-1 also stimulates chondrocytes to synthesize proteases and prostaglandin E2 while inhibiting the formation of extracellular matrix components.
Others have suggested that a defect in auricular embryogenesis contributes to pseudocyst formation. This defect causes the formation of residual tissue planes within the auricular cartilage. When subjected to repeated minor trauma or mechanical stress, these tissue planes may reopen, forming a pseudocyst.
Pseudocysts usually present spontaneously or following repeated minor trauma. [2] The observation that an auricular pseudocyst often results after repeated minor trauma, such as rubbing, minor sport injuries, ear pulling, sleeping on hard pillows, or wearing a motorcycle helmet or earphones, has led to the suggestion that these minor traumas may be the mechanism. In support of this traumatic etiology, elevated serum lactic dehydrogenase (LDH) values have been reported within the pseudocyst fluid. [4, 5] Two of the elevated isoenzymes, LDH-4 and LDH-5, are proposed as major components of human auricular cartilage. These enzymes may be released from auricular cartilage degenerated from repeated minor trauma.
One article reports that pseudocysts can be regarded as simply a variation of othematoma or otoseroma. [6]
Etiology
The etiology for pseudocysts of the auricle is unknown, but several pathogenic mechanisms have been proposed, including chronic low-grade trauma and spontaneous development. [7] Some have suggested that a minor defect in auricular embryogenesis can also contribute to pseudocyst formation. This defect may cause the formation of residual tissue planes within the auricular cartilage. When subjected to repeated minor trauma or mechanical stress, these tissue planes may open, forming a pseudocyst. The auricular cartilage in particular may be more susceptible to traumatic insult because of its lack of connective tissue overlying the cartilage with firm adherence to the skin. [8]
Consistent with the proposed mechanism, atopic dermatitis with accompanying facial and ear involvement may be a predisposing condition for pseudocyst formation. [9, 10] Although the incidence of pseudocysts in patients with atopic dermatitis appears to be low, these patients have an earlier occurrence of the condition and a greater incidence of bilateral lesions compared with the general population.
Pseudocyst has also been reported in a patient with intense pruritus who was later diagnosed with lymphoma. [11] After chemotherapy for the lymphoma, the pruritus improved with spontaneous reduction in the volume of the pseudocyst. The authors proposed that the trauma from scratching and rubbing of the ears was the major exacerbating cause of the pseudocyst.
Furthermore, pseudocysts have presented as a rare result following a relapse of polychondritis. Polychondritis is an uncommon autoimmune disorder associated with cartilaginous tissues on the nose and ear. The specific occurrence of auricle pseudocysts is very uncommon. [12]
Epidemiology
Frequency
Tan and Hsu reported the epidemiological features, clinicopathologic characteristics, and success of surgical treatment in 40 patients of different Asian groups presenting with pseudocyst of the auricle. [13] Results showed a Chinese predominance (90%), followed by Malays (5%), and Eurasians (5%). All except one patient had unilateral presentations. Most (55%) presented within 2 weeks of auricular swelling. Few (10%) had a history of trauma.
Race
Most reports of pseudocyst of the auricle have involved Chinese or white patients; however, persons of all racial groups have been affected.
Sex
Males show a higher prevalence of pseudocyst of the auricle than females. [14]
Age
Most pseudocysts of the auricle are unilateral and occur in men aged 30-40 years, but lesions are documented in patients ranging in age from 15-85 years of both sexes.
Prognosis
Without treatment of pseudocyst of the auricle, permanent deformity of the auricle may occur.
Patient Education
Patients with pseudocyst of the auricle should be informed that even with optimal therapy, recurrence is common. Avoidance of triggers or exacerbating factors should be encouraged.
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Asymptomatic nodule on the left ear.
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Low magnification of this pseudocyst reveals a mucin-containing cystic cavity.
Tables
|
Pseudocyst of the auricle |
Chondrodermatitis chronica helices |
Relapsing polychondritis |
Subperichondrial hematoma |
Swelling |
Localized |
Localized |
Diffuse |
Localized |
Skin involvement |
Rare |
Yes, crusting/ulceration |
Yes, erythematous |
Rare |
Pain |
Rare |
Common (from ulceration) |
Common (extremely tender) |
Common |
Systemic Symptoms |
No |
No |
Yes (involvement of other cartilage) |
No |
Histology |
Intracartilaginous, cystic defect, granulation tissue |
Subperichondrial granulation tissue, cystic dilatation rare |
Acute inflammable cells seen; antibody deposition on basement membrane during immunofluorescence |
Inflammatory cells with degraded blood products |
Adapted from Lim CM, et al. “Pseudocyst of the Auricle.” 2002. |
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