A rare case of primary pulmonary neuroendocrine tumor presenting with Cushing syndrome

Title-

'A rare case of primary pulmonary neuroendocrine tumor presenting with Cushing syndrome'

*Background*
Cushing syndrome is a rare endocrine disorder caused by excess cortisol production, leading to various clinical manifestations. Primary pulmonary neuroendocrine tumors (PNETs) are uncommon causes of ectopic Cushing syndrome, accounting for only 1-5% of all PNETs.

*Case Presentation*
We report a rare case of a 45-year-old female presenting with a 6-month history of weight gain, hypertension, and hyperglycemia. Physical examination revealed moon facies, buffalo hump, and purple striae. Laboratory tests confirmed hypercortisolism, with elevated 24 hour urine free cortisol and midnight cortisol levels. Imaging studies revealed a 3.5 cm right hilar mass. Histopathological examination and immunohistochemistry confirmed a primary pulmonary neuroendocrine tumor (PNET) of intermediate grade.

*Management and Outcome*
The patient underwent successful surgical resection of the tumor via a right upper lobectomy. Postoperative cortisol levels normalized, and Cushingoid features resolved. The patient remains disease-free at 12-month follow-up.

*Conclusion*
This case highlights the rare association between primary pulmonary neuroendocrine tumors and Cushing syndrome. Early recognition and surgical intervention can lead to successful management of this rare condition. This report contributes to the limited literature on this topic and emphasizes the importance of considering PNETs in the differential diagnosis of ectopic Cushing syndrome.