![]() ![]() The external auditory canal was packed with a Merocel wick to support the skin and to prevent canal stenosis for two weeks. The mass was removed while preserving the osteocartilaginous canal wall and the integrity of the underlying tympanic membrane. The patient underwent, under local anesthesia, an excisional biopsy of the mass via an intra-aural incision. The clinical and histological features, the differential diagnosis, and the treatment of apocrine hydrocystoma are discussed. ![]() A single, related case has been identified in the PUBMED database of an apocrine hidrocystoma involving the pinna and another one is reported in the Iranian Red Crescent Medical Journal. ![]() In the English literature, very few cases of apocrine hidrocystomas originating in the external auditory canal have been reported. We describe a patient with an apocrine hidrocystoma in the auricular canal. The general distribution of lesions tends to occur in similar locations on the body for both types of hidrocystomas, and ]. Apocrine lesions are also found mostly on the head and neck and along the eyelid margin near the inner canthus. Apocrine hidrocystomas arise from the proliferation of apocrine glands and are usually solitary, with a diameter of 3–15 mm. They are found predominantly in adult females, are located mostly on the periorbital and malar regions, and are prevalent in adults between 30 and 70 years of age. Eccrine hidrocystomas present as small, tense, thin-walled cysts, ranging from 1–6 mm in diameter, and can occur as single or multiple lesions. According to the histologic characteristics and presumed histogenic derivation, hidrocystomas have been categorized into two types (apocrine and eccrine). Hidrocystomas are rare, benign skin adnexal neoplasms, sometimes presenting as cystic lesions. These functions, along with the natural lateral migration of the meatal skin at the rate of 1,5 mm per month, play an important part in the antimicrobial defense mechanism of the ear canal. In addition, these glandular secretions provide a protective water proof coating for the skin. This acidity helps combat many organisms implicated in external canal infections, most of which grow best in an alkaline medium with a pH between 7,2 – 7,6. The acidity of these secretion keeps the pH of the auditory canal between 5,6 – 5,8 near the concha and to 7,3 – 7,5 at a distance of 5–10 mm within the canal. Cerumen itself derives from the sebaceous and apocrine glands of the ear canal. Whereas the function of eccrine sweat glands is to help regulate the body heat and fluid, the apocrine sweat glands have this role to a lesser degree and indeed, in the ear canal, have a more protective function. The secretion of the glands is strongly PAS positive and is at times stored in the gland lumina in sufficient quantities to cause glandular dilatation. They are comprised of an inner columnar, eosinophilic epithelium which is surrounded by an outer layer of myoepithelial cells. Histologicaly, the apocrine glands lie deep in the dermis adjacent to the cartilage. These glands secrete at a very low, constant rate. The number of these glands varies considerably, in individuals and in many races, with the primary concentration in the cartilaginous part of the canal, but with some sparse distribution in the osseous portion. Eccrine sweat glands are not present in the auditory canal, but it is abundantly supplied with modified (ceruminous) glands. Sebaceous glands are plentiful and open into the follicles of fine vellus hair. Hair follicles formed by invagination of epidermis are numerous in the outer one-third of the cartilaginous canal but are less noumerous in the inner two-thirds. ![]() The lateral one-third of the external auditory canal is cartilaginous and covered with a thin epithelium, firmly bound to the perichondrium and with scant subcutaneous tissue. ![]()
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