Acromegaly in an elderly male with hepatic malignancy: a case report of a diagnostic dilemma.

Introduction and importance: Acromegaly is usually caused by a growth hormone (GH)-secreting pituitary adenoma; nonpituitary causes are rare, especially in elderly patients. Paraneoplastic insulin-like growth factor-1 (IGF-1) excess from hepatic malignancy is quite uncommon, and its coexistence with a pituitary infundibular lesion presents a diagnostic challenge. Case Presentation: A 78-year-old diabetic man presented with coarse facial features, macroglossia, and increased interdental spacing. IGF-1 was elevated (218.6 ng/mL) with normal GH, ACTH, and prolactin. The 8 AM serum cortisol was high (36.27 μg/dL), suggesting ACTH-independent hypercortisolism. MRI brain revealed an enhancing pituitary infundibular lesion (pituicytoma vs granular cell tumor). CECT A + P exhibited a large hepatic mass with pulmonary metastases, elevated tumor markers (CEA, CA 19-9, AFP), and normal adrenal glands. Findings favored paraneoplastic IGF-1 excess and hypercortisolism from hepatic malignancy, with the pituitary lesion likely incidental. The family declined further workup, and the patient was lost to follow-up. Clinical discussion: Hepatic malignancy can rarely produce IGF-1 or cortisol-like substances, leading to acromegaly-like features and hypercortisolism independent of pituitary GH or ACTH secretion. The coexistence of paraneoplastic IGF-1 excess, ACTH-independent hypercortisolism, and an incidental pituitary lesion has not been previously reported. This case highlights the need to consider nonpituitary causes of acromegaly, especially in elderly patients with atypical biochemical or imaging findings. Conclusion: Non-pituitary causes of acromegaly should be considered in elderly patients with atypical biochemical profiles, as hepatic malignancy can rarely produce paraneoplastic IGF-1 excess even in the presence of incidental pituitary lesions.