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; non-pituitary causes are rare, especially in elderly patients. Paraneoplastic IGF-1 excess from hepatic malignancy is quite uncommon, and its coexistence with a pituitary infundibular lesion presents a diagnostic challenge. Case Presentation: 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. 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 non-pituitary 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.