Ectopic adrenocorticotropic hormone syndrome associated with olfactory neuroblastoma: acquirement of adrenocorticotropic hormone expression during disease course as shown by serial immunohistochemistry examinations

Ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS) is a condition of endogenous hypercortisolism sustained by an extrapituitary ACTH-secreting tumor. Olfactory neuroblastoma (ONB) is a rare malignant neoplasm of the sinonasal tract and is derived from the olfactory epithelium. Because the paranasal sinus is not a common site of EAS, the development of ONB in patients with EAS is rare. We herein report the first known case of ONB with acquirement of ACTH production during the clinical course as proven by immunohistochemistry. A 50-year-old man diagnosed with ONB was referred to our department in July 2015 because of hypokalemia, hyperglycemia, decreased eosinophil and granulocyte counts, and elevated serum levels of ACTH and cortisol. Although two previous ONB biopsy specimens (2011 and 2014) showed no ACTH immunoreactivity, a newly obtained specimen in August 2015 clearly showed ACTH immunoreactivity. This is the first case of ectopic ACTH syndrome associated with an ONB that acquired the ability to express ACTH during its clinical course as shown by serial immunohistochemical examinations.

Two cases of ectopic adrenocorticotropic hormone syndrome with olfactory neuroblastoma and literature review

Olfactory neuroblastomas are rare, slow-growing malignant tumors, usually diagnosed at advanced stages. Ectopic adrenocorticotropic hormone (ACTH) syndrome caused by an olfactory neuroblastoma is extremely rare. We reported two Korean women who suffered from ectopic ACTH syndrome (EAS) caused by olfactory neuroblastomas. The first patient was a 66-year-old woman who had been diagnosed as olfactory neuroblastoma and refused the management two years before and the second patient was a 37-year-old woman on chemotherapy for olfactory neuroblastoma. In the first case, she presented the Cushingoid appearance with systemic edema and her tumor was removed surgically. ACTH secretion by the tissue was confirmed by immunohistochemistry. By contrast, the second patient presented as severe pneumonia caused by cytomegalovirus and was treated with anti-viral agent followed by chemotherapy and radiotherapy, and her residual mass remained. However, after treatment, both patients' plasma ACTH and cortisol levels returned to normal without any adrenolytic therapy. Considering the causative tumors of EAS can be rarely cured and EAS increases the susceptibility to infections, it is prudent to suppress any hypercortisolemia initially, apart from treating the causal malignancy.

Olfactory neuroblastoma causing ectopic ACTH syndrome

A 39-year-old woman who presented with typical Cushingoid appearance (moon facies, central obesity, purpura) was admitted to our hospital because of pulmonary infection. She was found to have hypertension, severe hypokalemia, and metabolic alkalosis. Endocrine data revealed elevated plasma levels of ACTH and cortisol with lack of circadian rhythm, non-suppressibility to high-dose dexamethasone, and hyperresponsiveness to CRH stimulation. Although no pituitary mass was detected by MRI of the brain, inferior petrosal sinus sampling showed a step-up of central to peripheral ACTH levels; these data are consistent with the diagnosis of Cushing's disease. She was successfully treated with metyrapone to control hypercortisolemia. Ten months later, a mass was detected in the ethmoid sinus, which was surgically removed. After resection of the ethmoid sinus tumor, her Cushingoid features and hypercortisolemia disappeared, but recurred after enlargement of a second mass in the maxillary sinus. After resection of the maxillary sinus tumor, her hypercortisolemia subsided. Histologically, the tumor tissues from both the ethmoid and maxillary sinus were identical and consistent with the diagnosis of olfactory neuroblastoma. Immunohistochemically, the immunoreactivities of ACTH and POMC were positive in the cytoplasm of tumor cells, and immunoreactive ACTH was demonstrated in both tumor tissues. Thus, this is the second rare case with ectopic ACTH syndrome caused by olfactory neuroblastoma thus far reported.