Sphenoid sinus carcinoid tumour causing ectopic ACTH syndrome

Unusual ectopic ACTH syndrome in a patient with orbital neuroendocrine tumor, resulted false-positive outcome of BIPSS:a case report

BACKGROUND

Cushing's syndrome has been described as a complex endocrine disorder characterized with high cortisol concentration. Correct and early diagnosis of Cushing's syndrome is challenging. According to the latest guideline, bilateral inferior petrosal sinus sampling (BIPSS) is considered to be the gold standard for the differential diagnosis. However, in some unusual cases, this method may be false positive. Here, we presented a rare case of orbital neuroendocrine tumor secreting adrenocorticotrophic hormone with false positive inferior petrosal sinus sampling.

CASE PRESENTATION

A 48-year-old woman was admitted to West China Hospital of Sichuan University, presenting with fatigue, whole body edema for 1 year, alopecia and skin pigmentation for 5 months. Hormonal profiles including plasma cortisol and adrenocorticotrophic hormone (ACTH) measurements and low-dose dexamethasone inhibition test suggested that the patient had Cushing's syndrome. However, during tumor location phase, the results of high-dose dexamethasone inhibition test (HDDST) contradicted desmopressin (DDAVP) stimulation test. Thus, BIPSS was employed, and its results indicated a pituitary origin. Interestingly, MRI of sellar region showed an innocent pituitary but caught a serendipitous lesion in the lateral rectus muscle of left eye, which was later proved to be an orbital neuroendocrine tumor secreting ACTH by pathological and immunohistochemical results. ACTH level of the patients was < 0.1 ng/L and cortisol level was 51.61 nmol/L 1 week after surgery. At 24 months follow-up, the patient appeared stable with no complaints nor any symptoms of Cushing's syndrome, including moon face, purple striate and central obesity. The patient's life quality also improved significantly.

CONCLUSION

We reported a rare case of endogenous Cushing's syndrome due to ectopic ACTH secreting from an orbital neuroendocrine tumor. This unique case of orbital EAS suggests that orbital venous blood backflow, owning to abnormal anatomic structures, may possibly lead to false positive BIPSS results.

Carcinoid Tumor Arising from the Sphenoid Sinus Treated with Definitive Intensity-modulated Radiation Therapy: A Case Report

Head and neck neuroendocrine tumors (NET) are a rare type of cancer. NET can be classified according to the histopathological features. The typical carcinoid tumor is a well-differentiated tumor that is the least common among other types. Owing to its indolent behavior and variable radiological and pathological features, treatment of carcinoid tumors remains a challenge. We report a case of a 54-year-old man presenting with a non-operable carcinoid tumor arising in the sphenoid sinuses treated with radiotherapy with stable disease control after three years follow-up.