Scleroderma-Like Phenotype in a Patient With Transthyretin Cardiac Amyloidosis and Acromegaly: A Triple Diagnostic Challenge

Systemic sclerosis, transthyretin cardiac amyloidosis, and acromegaly are rare disorders that share several clinical manifestations, including skin thickening, heart failure, dysphagia, fatigue, and soft tissue enlargement. Their coexistence is exceptionally rare and poses a significant diagnostic challenge, increasing the risk of premature diagnostic closure. We report a 78-year-old man who developed progressive diffuse skin thickening following spinal cord stimulator revision. Positive RNA polymerase III antibodies supported a diagnosis of diffuse systemic sclerosis. Evaluation of worsening edema and exertional dyspnea revealed severe concentric left ventricular hypertrophy with relative apical sparing on echocardiography, and technetium-99m pyrophosphate scintigraphy confirmed transthyretin cardiac amyloidosis. Persistent macroglossia, coarse facial features, prior carpal tunnel syndrome, and a remote history of increasing ring and shoe size prompted endocrine evaluation, which demonstrated elevated insulin-like growth factor-1 levels, failure of growth hormone suppression, and a pituitary macroadenoma consistent with acromegaly. The patient underwent successful transsphenoidal resection with biochemical remission. This case highlights the importance of reconsidering the differential diagnosis when clinical features are not fully explained by an established diagnosis. Recognizing atypical and discordant findings prevented premature diagnostic closure and led to the identification of transthyretin cardiac amyloidosis and acromegaly in a patient with a rapidly progressive scleroderma-like phenotype.