The skin of the external auditory canal, just like skin elsewhere in the body, contains several types of adnexal secretory glands, including eccrine (common sweat glands), apocrine (modified sweat glands), and holocrine (sebaceous) glands. The external canal skin also contains ceruminous glands, essentially apocrine glands, which, in combination with the sebaceous glands, create cerumen [
Several types of solid tumors have been reported to originate from these glands, both benign, such as ceruminous adenomas, and malignant, such as ceruminous adenocarcinomas [
Here, we present a rare case of an eccrine hidrocystoma, confined to the external auditory canal in an adult patient. The lesion was surgically excised using endoscopic ear surgery techniques. There was no recurrence, EAC stenosis, or other complications.
A 67-year-old woman presented to our otolaryngology clinic complaining of a lesion in her left ear canal that had been growing slowly for approximately 10 years. She had prior bilateral mastoidectomies (intact canal wall) for chronic otitis media as a child. Over the past 20+ years, her ear symptoms have been quiescent and there is no ongoing inflammatory process in her ears. She has some mixed hearing loss and wears bilateral hearing aids. Recently, the lesion in her left ear canal has interfered with hearing aid placement. On otoscopic examination, a soft, nontender, ovoid, smooth, bluish mass about 1 cm in diameter was noted partially blocking the left EAC meatus (Figure
A bluish lesion is seen in the external auditory canal inferiorly, partially blocking the canal lumen.
Her tympanic membrane, which could still be partially visualized past the lesion, appeared grossly intact with normal landmarks. Audiometry was consistent with a severe to profound mixed hearing loss bilaterally. Tympanometry was normal (type A) on the right, but on the left ear, a seal could not be achieved.
To evaluate the deep extent of the lesion, the patient underwent a CT scan of the temporal bones without contrast, which revealed a well-circumscribed 1.0 × 0.8 cm sessile cystic lesion arising from the floor of the lateral portion of the left external auditory canal. A thin rim of calcification could be seen along the inferior margin of the lesion. There was no evidence of invasion of surrounding soft tissues or bone. The tympanic membrane, middle ear cleft, and ossicular chain were intact and normal. Prior mastoidectomies were evident on CT images (Figure
CT of the temporal bones shows a well-defined cystic lesion originating from the anterolateral portion of the left external auditory canal. The lesion has no deep extension, does not show any bone erosion, and does not involve the middle ear cleft.
Because of the benign features of the lesion on history, examination, and imaging, decision was made to proceed with local excision of the lesion with minimal margins. The patient was taken to the operating room for excision of this lesion under general anesthesia, using the otologic endoscope and binocular otomicroscopy. The mass was completely enucleated via a transcanal approach. The lesion was broadly attached to the anteroinferior surface of the external auditory canal but did not involve the bony canal or the tragal cartilage. Minimal bleeding was encountered which was controlled with simple pressure. No skin closure was needed for the resultant defect of less than 10 mm diameter. Bacitracin ointment was applied to the wound. After excision, the bluish smooth cystic lesion was opened and dark brown liquid was seen emanating from the lumen (Figure
A bluish smooth cystic lesion is excised with some overlying skin. The lesion contains brown liquid.
Histopathological examination showed skin with multiple small dermal cysts ranging from 2 to 5 millimeters, with scattered normal sweat glands present between the cysts (Figure
Histopathologic examination shows external auditory canal skin with multiple dermal cysts. A focus of normal sweat glands is present between the cysts in the middle of the photomicrograph (arrow).
Close-up of a cyst wall demonstrates a cuboidal double-layered epithelium, consistent with an eccrine hidrocystoma.
The patient did well postoperatively with no complications. A postoperative audiogram revealed stable hearing and normal tympanometry (type A) bilaterally. The wound site epithelialized well and the surgical site healed without scarring or stenosis. The lesion did not recur during the 12-month follow-up period. The patient was now able to use her hearing aids without difficulty.
Hidrocystomas of the external ear canal are rare, benign cystic lesions and are generally categorized as apocrine or eccrine [
Eccrine hidrocystomas are characterized by the presence of cysts lined with attenuated double-layered epithelium which lack features of apocrine cell differentiation, such as decapitation secretion and tall columnar cells with eosinophilic cytoplasm. Scattered benign sweat glands are often found admixed with the cystic glands. Some authors suggest that eccrine hidrocystomas may actually be of apocrine type, with the typical apocrine features attenuated due to the intraluminal pressure of the cyst fluid [
Surgical excision is the treatment of choice. In patients with multiple hidrocystomas, or lesions that are not easily accessible to surgery, alternative treatments exist, such as topical atropine, scopolamine cream, botulinum toxin injection, or CO2 laser ablation [
While hidrocystomas are generally uncommon cystic lesions of the sweat glands, it is quite rare to find an eccrine hidrocystoma originating from the skin of the external auditory canal. The slow growing nature and smooth, solitary, cystic appearance, in addition to the bluish tint, can provide valuable diagnostic clues [
Written informed consent was obtained from the patient for publication of this report and images. A copy of the written consent is available for review upon request.
There are no competing interests to report for any of the three authors.
Taha Mur participated in choosing the study design, reviewed the literature, wrote the manuscript, and edited the manuscript. Ronald Miick is the pathologist who reviewed the pathology slides, reviewed the literature, wrote the histopathology related parts of the manuscript, and edited the manuscript. Natasha Pollak is the senior author who cared for the patient. She chose the study design, reviewed the literature, wrote parts of the manuscript, and edited the entire manuscript.