Endocrine Abstracts

Background: Ectopic ACTH secretion from metastatic acinic cell carcinoma (ACC) of the parotid gland is extremely rare. ACC is an uncommon, typically indolent, salivary gland neoplasm. Herein, we report a case of a high-grade ACC later diagnosed with Cushing’s syndrome (CS).

Case presentation: A 60-year-old man presented with a laterocervical mass. Computed tomography (CT) documented a 39×38 mm mass on the parotid gland and homolateral cervical lymph nodes. Further imaging revealed mediastinal, bone and multiple pulmonary lesions. Parotid fine-needle aspiration cytology and CT-guided biopsy of the lung nodule were compatible with ACC. The patient was referred to parotidectomy with cervical lymph node dissection. While waiting for surgery, severe hypertension, dyslipidaemia, new-onset insulin-dependent diabetes mellitus and hypokalaemia developed. Plasma basal ACTH and 24-urinary free cortisol were markedly elevated. ACTH immunohistochemistry was performed in one of the pathology specimens and immunostaining was observed, confirming the diagnosis of ACTH-dependent CS. Hypercortisolism was managed with metyrapone with early clinical and biochemical response. Local disease progression with skull base involvement precluded surgery, and radiotherapy (RT) for the parotid and cervical lesions was performed, with significant reduction of local disease. Metastatic bone lesions were treated with symptomatic RT. Decrease in antihypertensive therapy, progressive discontinuation of insulin therapy and withdraw of potassium supplementation were noticed after RT and medical treatment. The patient is currently receiving palliative chemotherapy due to progressive pulmonary disease and maintains metyrapone at the last follow-up.

Conclusions: Only ten cases of ACTH-dependent CS secondary to ACC were reported. The unusual presentation of ACC with metastatic disease, as well as the successful improvement of CS after treatment, make this a unique case report among the literature.