OBJECTIVE: To report a common site of external ear canal erosion in multiple pathologies, located inferiorly at 6 o\'clock.
METHODS: Otology patients who came in 2023 for treatment of external auditory canal erosions.
METHODS: This clinical capsule is an observational report of the external canal\'s propensity to erosion at the 6 o\'clock location. Patient treatments were canalplasty, mastoidectomy, and medical management.
METHODS: Documentation of the propensity to erosion at the 6 o\'clock location in the external auditory canal. Locations of the niduses of prior series of external auditory canal pathologies are documented.
RESULTS: Eight patients are presented with external auditory canal erosion in 10 ears originating at the 6 o\'clock position medial to the bony-cartilaginous junction. No other patient with spontaneous canal erosion presented with their nidus of pathology in another canal location. (A review of 42 case series of 291 patients found that keratosis obturans and bisphosphonate-induced osteonecrosis tended to arise from the same 6 o\'clock lateral bony canal location, while 26% of necrotizing otitis externa cases arose there.).
CONCLUSIONS: The \"6 o\'clock spot\" in the external canal is a common location of canal erosion for spontaneous wax and keratin collections and may be the precursor to keratosis obturans, bisphosphonate-induced osteonecrosis of the ear canal, and necrotizing otitis externa.

OBJECTIVE: To systematically review the literature and understand the behavior, diagnosis, management, and mortality of metastasis to the external auditory canal (EAC).
UNASSIGNED: PubMed/Medline, EMBASE, Web of Science.
METHODS: Studies from 1948 to June 2023 describing metastasis to the EAC were included. Non-English literature was excluded. Data extraction: Study design, age, sex, pathology, primary site, staging, additional sites of metastasis, time to EAC metastasis from diagnosis, time from diagnosis of EAC metastasis to death, symptoms, exam and imaging findings, and management.
RESULTS: Data were synthesized qualitatively with means calculated. Thirty-two studies met the criteria, totaling 37 patients with EAC metastasis. Mean age was 58 years; 73% were male. The most common pathologies were adenocarcinoma (37.8%), acute myelogenous leukemia (8.1%), and renal cell carcinoma (8.1%). Sites of primary malignancy were hematologic (10.8%), breast (8.1%), esophagus (8.1%), renal (8.1%), and prostate (8.1%). Within the temporal bone, 73% had isolated EAC metastasis. Median time to EAC metastasis from the diagnosis of primary malignancy was 18 months. Metastasis to the EAC was the first presentation of malignancy in 21.6% of patients. Median time to death was 4.5 months. Symptoms included hearing loss (59.5%), otalgia (27.0%), otorrhagia (24.3%), facial paralysis (21.6%), otorrhea (16.2%), and aural fullness (13.5%). On imaging, bony erosion was present in 50% of cases. Treatment was primarily palliative with excision and radiation.
CONCLUSIONS: EAC metastasis has a distinct presentation from other temporal bone subsites. Early biopsy to establish a diagnosis and intervene is critical.

Cerumen lubricates and protects the external auditory canal, but excess accumulation can lead to ear fullness, itching, otalgia, discharge, hearing loss, and tinnitus. Cerumen should be treated whenever symptoms are present or if it limits diagnosis by preventing a needed otoscopic examination. Clinicians should evaluate for cerumen impaction in those using hearing aids and patients with intellectual disability. Cerumen impaction can be treated with cerumenolytics, ear irrigation, and manual removal with instrumentation. Aural foreign bodies can cause ear fullness, otalgia, discharge, and hearing loss. They are more common in children than adults. The most common type of aural foreign bodies in children is jewelry, followed by paper products, parts of pens or pencils, desk supplies (eg, erasers), BBs or pellets, and earplugs or earphones. In adults, the most common aural foreign bodies are cotton swabs or cotton, followed by hearing aid parts and jewelry or ear accessories. Patients should avoid using cotton tip applicators in the external auditory canal. Alligator forceps, small right angle hooks, and ear irrigation commonly are used to remove aural foreign bodies in an outpatient clinic setting, but the choice depends on the type of foreign body. Soft and irregularly shaped objects can be removed without referral to an otolaryngologist. Patients with hard, spherical, or cylindrical objects should be referred to an otolaryngologist if previous removal attempts have failed or if there is ear trauma to avoid worsening its position in the ear canal.

Melanoma of the external auditory canal (EAC) is particularly rare and poorly understood, with limited available data on management and survival. This systematic review aims to analyze existing data and provide insights into the management and prognosis the beginning of EAC melanoma. It is conducted using Pubmed and Scopus databases from the beginning to July 2023 and it follows the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 guidelines. Searches are performed using the search string \"(melanoma) AND (external auditory canal)\".
The review includes a total of 30 patients diagnosed with EAC melanoma, supplemented by an additional case from the authors\' clinical experience. The role of Breslow thickness as a determining factor for the choice of surgery remains inconclusive due to limited available data. Sentinel lymph node biopsy and adjuvant therapy are sparingly employed, indicating the need for standardized guidelines. Patients in the study demonstrate a 50% overall survival rate at 5 years.
EAC Melanoma is a rare and aggressive malignancy with limited therapeutic guidelines. Surgical interventions, including wide local excision and lateral temporal bone resection, are the primary treatment options for patients without distant metastases.

Poor utilization of earplugs among military personnel may be due to discomfort caused by the occlusion effect (OE). The OE occurs when an earplug occludes the ear canal, thereby changing bone conduction (BC) hearing and amplifying physiological noises from the wearer. There is a need to understand and reduce the OE in the human ear. A 3D finite element model of the human ear including a 3-chambered spiral cochlea was employed to simulate the OE caused by foam and aerogel earplugs. 90 dB sound pressure was applied at the ear canal entrance and BC sound was applied as vibration of the canal bony wall. The model reported the ear canal pressure and the displacements of the stapes footplate and cochlear basilar membrane with and without earplugs. Without BC stimulation, the foam earplug showed a greater pressure attenuation than the aerogel earplug. However, the foam earplug results were more affected by BC stimulation, with a maximum sound pressure increase of 34 dB, compared to the 21.0 dB increase with the aerogel earplug. The aerogel earplug\'s lower OE demonstrates its promise as an earplug material. Future work with this model will examine BC sound transmission in the cochlea.

This study aims to examine the effectiveness of mycocins produced by Wickerhamomyces anomalus in inhibiting Malassezia pachydermatis, a yeast commonly found in the ear canal of dogs. M. pachydermatis has a zoophilic origin and can be found in mammals, and frequently in dogs, where it mainly colonizes the ear canal region and the skin, leading to lesions that are difficult to treat. The antimicrobial mechanism was evaluated using dilutions of supernatant with enzymatic activity, which may include β-glucanases, glycoproteins known to act on microorganism cell walls. However, it is important to note that this supernatant may contain other compounds as well. β-glucanases in the mycocins supernatant were found at a concentration of 0.8 U/mg. The susceptibility of M. pachydermatis isolates was tested using the microdilution method. The isolates suffered 100% inhibition when tested with the culture supernatant containing mycocins. In the proteinases production test, 44% of the isolates tested were strong proteinases producers. Subsequently all these isolates suffered inhibition of their activity when tested in research medium containing mycocins supernatant at a subinhibitory concentration of β-glucanases. This shows that mycocins can inhibit the production of proteinases, a virulence factor of M. pachydermatis. The viability test showed the antifungal action of mycocins in inhibiting the viability of M. pachydermatis cells after a period of 8  hours of contact. These results support the antimicrobial potential of mycocins and their promise as a therapeutic option.

This report presents a rare case of bronchogenic adenocarcinoma with initial metastasis in the external auditory canal. The patient, a 64-year-old man with a history of bladder urothelial carcinoma, initially presented with a persistent right otitis externa. Otoscopic examination revealed a mass obstructing the right external auditory canal. The temporal bone computed tomography scan revealed a mass that completely obstructed the right external auditory canal and extended into the middle ear. A biopsy showed a poorly differentiated adenocarcinoma of bronchogenic origin, confirmed by positive immunohistochemical staining for cytokeratin 7 and Thyroid transcription factor-1. Further imaging revealed a large tumor mass in the lung involving the mediastinum and parenchyma, along with carcinomatous lymphangitis and cerebral metastasis. Histopathological examination of the primary lung tumor confirmed a poorly differentiated adenocarcinoma with similar features to the metastasis in the external auditory canal. The tumor was staged as T4N2M1c, and the patient underwent local external-beam radiation therapy with chemotherapy.

OBJECTIVE: To investigate the microbial changes of long-term hearing aid use culture independently.
METHODS: Cross-sectional study.
METHODS: Fifty long-term hearing aid users and 80 volunteer controls with asymptomatic ears.
METHODS: External auditory canal (EAC) sampling with DNA-free swabs.
METHODS: Microbial communities in the samples were investigated with amplicon sequencing of the 16S rRNA gene.
RESULTS: The final analysis contained 48 hearing aid users, 59 controls. Twenty-four samples were excluded because of low sequence count, recent use of antimicrobials and/or corticosteroids, recent cold, or missing health status. The groups showed significant differences in bacterial diversity (beta div., p = 0.011), and hearing aid users showed lower species richness than the control group (alpha div., p < 0.01). The most frequent findings in both groups were Staphylococcus auricularis , Alloiococcus otitis , Cutibacterium acnes , Corynebacterium otitidis , and Staphylococcus unclassified sp. Hearing aid users\' samples presented more Corynebacterium tuberculostearicum than the control samples. Common EAC pathogens, such as Staphylococcus aureus or Pseudomonas aeruginosa were rare.
CONCLUSIONS: Long-term hearing aid use lowers bacterial diversity and modulates the EAC microbiome. The changes mostly affect commensals. Lowered diversity may predispose individuals to EAC conditions and needs more research.

Trichoblastoma（TB） is a rare germ cell skin adnexal tumor of the hair, and it is a rare follicular tumor of the skin that differentiates from the hair germ epithelium and is often regarded as a benign skin tumorHowever, it is poorly confined and has a local infiltrative growth pattern. tb occurs in the head and neck region, especially in the face, and presents clinically as a slow growing, well-defined and elevated nodule. TB is routinely treated surgically. Due to the lack of universally accepted treatment guidelines or protocols, the recurrence rate after surgery is high, which makes clinical cure more difficult. In this study, a 65-year-old female patient was found to have a swelling with recurrent rupture and pus flow from the right external auditory canal opening and the auricular cavity. After initial misdiagnosis as otitis externa, she was treated with conventional anti-infective therapy, but her symptoms did not resolve and gradually worsened before coming to our hospital. The condition presented in this case is relativelyrare,therepre,timely and accurate diagnosis and treatment are crucial for prognosis improvement of such diseases.
摘要: 毛母细胞瘤（trichoblastoma，TB）是一种罕见的毛发生殖细胞皮肤附件肿瘤，罕见的皮肤滤泡肿瘤，分化于毛胚上皮，常被视为良性皮肤肿瘤，但局限性差且具有局部浸润性生长模式。TB好发于头部和颈部区域，尤其是面部，临床表现为生长缓慢、边界清晰及隆起的结节。TB常规以手术治疗为主，由于目前缺乏普遍接受的治疗指南或方案，术后复发率高，为临床治愈增加了一定的难度。本研究报道1例65岁女性患者，发现右侧外耳道口及耳甲腔肿物并反复破溃流脓，最初误诊为外耳道炎，以常规抗感染治疗，症状未缓解并逐渐加重后来我院就诊。该病例所展现的病症极为罕见，因此，及时且准确的诊断与治疗对此类疫病的诊疗和预后至关重要。.

Malassezia yeasts belong to the normal skin microbiota of a wide range of warm-blooded animals. However, their significance in cattle is still poorly understood. In the present study, the mycobiota of the external ear canal of 20 healthy dairy Holstein cows was assessed by cytology, culture, PCR, and next-generation sequencing. The presence of Malassezia was detected in 15 cows by cytology and PCR. The metagenomic analysis revealed that Ascomycota was the predominant phylum but M. pachydermatis the main species. The Malassezia phylotype 131 was detected in low abundance. Nor M. nana nor M. equina were detected in the samples.
The mycobiota of the external ear canal of healthy cows was assessed by cytology, culture, PCR, and NGS. The presence of Malassezia was detected by cytology and PCR. Ascomycota was the main phylum and M. pachydermatis the main species. The Malassezia phylotype 131 was also detected in the samples.