Merkel cell tumour of the external ear. Report of a case

Exploring diagnosis and therapeutic complexities of an aggressive Merkel cell carcinoma: A case report and review of the literature

Merkel cell carcinoma (MCC) is an aggressive and rare cutaneous neuroendocrine carcinoma that predominantly affects the sun-damaged skin of the head and neck region, extremities, and trunk of older white individuals. Microscopically, MCC is characterized by nests or sheets of uniform small round blue cells with scant cytoplasm, granular nuclei with a salt-and-pepper chromatin pattern, high proliferative activity, and occasional necrosis. They are usually positive for epithelial and neuroendocrine markers, particularly for cytokeratin 20 and AE1/AE3 in a paranuclear dot-like staining. We herein contribute by reporting a case of MCC affecting the auricular pavilion of a 66-year-old female patient from Campinas, Brazil. Additionally, a review of the current literature is also included to analyze all the cases that have been reported in the English-language literature, totalizing 27 cases of MCC on the external ear. The 5-year overall survival rate for individuals with localized MCC is 50% and the most common treatment choice is the combination of surgery with adjuvant radiotherapy and sentinel lymph node biopsy.

A Rare Presentation of Primary Cutaneous Low-Grade Neuroendocrine Tumor of the External Auditory Canal

OBJECTIVE

To describe the first case of a primary cutaneous low-grade neuroendocrine tumor (cLGNET) originating from the external auditory canal as well as our team's surgical management.

PATIENT

A healthy 34-year-old female presented with a low-grade neuroendocrine tumor of her right external auditory canal (EAC) which extended from the posterior-superior aspect of the EAC into the middle ear.

INTERVENTION

A complete otological examination was performed in addition to CT and MRI imaging. The low-grade neuroendocrine tumor was surgically biopsied and further surgery was recommended for complete resection.

RESULTS

Audiogram revealed profound right sensorineural hearing loss. CT scan demonstrated complete opacification of the right EAC, middle ear, and mastoid air cells, dystrophic calcification in the mesotympanum overlying the cochlear promontory, and no associated osseous erosion. MRI revealed abnormal FLAIR hyperintensity and enhancement of the labyrinthine segment of the right facial nerve, cochlea, and horizontal and posterior semicircular canals. An enhancing mass opacifying the right EAC demonstrating restricted diffusion on diffusion-weighted image was also evident. Pathologic examination and immunohistochemical staining confirmed a diagnosis of primary cLGNET of the EAC.

CONCLUSION

Primary cLGNETs of the external ear are exceedingly rare but should be considered if an adult patient presents with a mass in the EAC. Management should include early biopsy and surgical excision followed by histological and immunohistochemical confirmation.

Primary carcinoid tumor in the external auditory canal

A 39-year-old man visited the department of otolaryngology due to an ongoing hearing disturbance that had lasted for 1 year. Temporal bone computed tomography revealed soft tissue density nearly obliterating the left external auditory canal (EAC). The mass was composed of sheets of round tumor cells containing moderate amounts of fine granular cytoplasm and salt and pepper chromatin. Neither mitosis nor necrosis was found. The Ki-67 proliferation index was less than 2%. Cells were positive for CD56 and synaptophysin but negative for chromogranin, cytokeratin (CK) 20, and CK7. Based on these findings, the tumor was diagnosed as a carcinoid tumor, well differentiated neuroendocrine carcinoma, grade 1 (G1) according to current World Health Organization (WHO) classification of head and neck tumors; and a neuroendocrine tumor, G1 according to neuroendocrine neoplasm (NEN)-2018 WHO standard classification. He remained free of local recurrence and metastasis after 20 months of follow up. To date, only six cases of primary NENs in the EAC have been reported. Metastatic tumor should be included in the differential diagnoses. Because of its rarity, the prognosis and treatment have not yet been clarified.

Merkel cell carcinoma: a systematic review of ENT presentations

The aim of this study was to perform a systematic literature review of Merkel cell carcinomas (MCCs) originating exclusively in the ear, nose and throat (ENT) district. An appropriate string was run on PubMed to retrieve articles dealing with ENT presentations of MCC. A double cross-check was performed on citations and full-text articles found using the selected inclusion and exclusion criteria. In total, 43 articles were finally included in the study, describing 51 cases of MCC involving the ENT region: 22/51 (43%) cases involving the ear; 20/51 (39%) cases involving the mucosal sites; 9/51 (18%) cases involving other ENT regions. Patients with mucosal site involvement showed a higher mortality rate from the disease (45%) in comparison with the other two groups, especially when compared with those patients having primary involvement of the ear (22%). The ENT specialist should suspect and consider MCC, especially in elderly patients presenting with a suspicious lesion of the auricular pavilion, so as to avoid misdiagnosis and delayed treatments.

Cutaneous neuroendocrine carcinoma of the external auditory canal: a case report and review of the literature

Cutaneous neuroendocrine carcinoma (cNEC) is rarely seen in the external ear. In this paper, we newly describe a patient with cNEC in his right external auditory canal, followed by a further discussion on the clinical features, diagnosis, and treatments of cNEC of the external ear. A review of the literature showed that cNEC of the external auditory canal generally presents as asymptomatic and that pathology yields the most confirmative diagnosis. A wide resection with adjuvant radiotherapy and chemotherapy is recommended. The overall prognosis of this condition is poor.

A comprehensive review of the treatment of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is an uncommon but malignant cutaneous neuroendocrine carcinoma with a high incidence of local recurrence, regional lymph node metastases, and subsequent distant metastases. The etiology of MCC remains unknown. It usually occurs in sun-exposed areas in elderly people, many of whom have a history of other synchronous or metachronous sun-associated skin lesions. The outcome for most patients with MCC is generally poor. Surgery is the mainstay of treatment. The role of adjuvant therapy has been debated. However, data from recent development support a multimodality approach, including surgical excision of primary tumor with adequate margins and sentinel lymph node dissection followed by postoperative radiotherapy in most cases, as current choice of practice with better locoregional control and disease-free survival. Patients with regional nodal involvement or advanced disease should undergo nodal dissection followed by adjuvant radiotherapy and, perhaps, systemic platinum-based chemotherapy in most cases.