AB125. SOH21AS255. Intradermal naevi occurring in the external auditory canal, 2 cases from an Irish Otolaryngology Service

Background: An intradermal naevus is a benign cutaneous neoplasm belonging to the group of melanocytic naevi. They are clusters or nests of melanocytic cells located in the epidermis or dermis. Intradermal naevi are commonly occurring skin lesions. However occurrence in the external auditory canal (EAC) is relatively uncommon. Less than 50 cases have been reported in the English literature to date. We report two cases of benign intradermal naevi occurring in the EAC encountered in an Irish otolaryngology service.

Methods: Case 1, a 39-year-old woman with a sensation of ear fullness presented to her GP ear syringing and was found to have a right EAC lesion. Biopsy of the lesion confirmed an intradermal naevus. It was resected without complications. Case 2, a 28-year-old woman was incidentally found to have a non-pigmented naevus in her left EAC at an otolaryngology clinic. She was asymptomatic at discovery and a biopsy confirmed an intradermal naevus. After 12 years of follow up, the lesion was observed to have enlarged. She had an uncomplicated excision carried out.

Conclusions: Intradermal naevi occur as a result of benign proliferation of melanocytes. When occurring in the EAC they most often present with conductive hearing loss. They can be flat, elevated, papillomatous, dome-shaped or pedunculated lesions. Histologically, they are identified by the presence of nevus cells which are melanocytes arranged in nests and can be junctional, compound or intradermal. Intradermal nevi can mimic the appearance of seborrheic keratosis, Kaposi’s sarcoma, common warts or malignant lesions such as squamous cell carcinoma and malignant melanoma. It is recommended that all should be excised to rule out the possibility of melanoma.

Keywords: Intradermal naevi; otology; skin lesions