Metastatic Ceruminous Adenoid Cystic Carcinoma of the Lumbar Spine Causing Neurological Compromise: A Case Report.

Background: Ceruminous glands are modified apocrine glands of the external auditory canal (EAC). Malignant tumours within the ceruminous glands are extremely rare, and the most common histological type is adenoid cystic carcinoma (ADCC), which has high recurrence and metastasis risks. Although a few cases of metastatic ADCC from other head and neck glands have been reported, metastatic ADCC originating from the ceruminous gland are extremely rare. Case presentation: We present an unusual case of spinal metastases of ADCC from ceruminous glands. A 61-year-old woman complaining of low back pain and both lower limbs pain was referred to our department. The primary ceruminous tumour was resected 26 years ago and recurred 6 years later, which was treated by radiotherapy. Three years ago, she presented with low back pain and was diagnosed as multiple lungs and bone metastases. The patient underwent tumour excision, decompression and fusion. The biopsy revealed metastatic ADCC. The symptoms were alleviated after surgery. Conclusions: ADCC of EAC is a pernicious malignant tumour that is characterized by slow-growing patterns and a high predisposition to recurrence and metastasis. Differential diagnoses of ADCC and benign tumours in the EAC are challenging, particularly at early stages. We report a rare case of ceruminous ADCC with a prolonged clinical history as well as spinal metastasis and highlight the significance of regular follow-ups for patients undergoing tumour excision in the EAC.