Papillary thyroid carcinoma presenting as paraneoplastic acral vascular syndrome in a 37-year-old female: A case report.

BACKGROUND: Paraneoplastic acral vascular syndrome is a rare condition associated with various malignancies, most commonly adenocarcinomas. It manifests as digital ischemia, including Raynaud's phenomenon, acrocyanosis, and digital gangrene. Reported cases typically show improvement after treatment of the underlying cancer. We describe the first known case of paraneoplastic acral vascular syndrome secondary to papillary thyroid carcinoma (PTC), with complete resolution following thyroidectomy. CASE PRESENTATION: A 37-year-old previously healthy woman was referred from the vascular surgery clinic for evaluation of episodic digital discoloration. She reported a four-year history of recurrent Raynaud-like color changes affecting the middle fingers of both hands and the lateral four toes of both feet. She denied symptoms suggestive of connective tissue disease, inflammatory arthritis, autoimmune disorders, or cardiovascular disease, as well as tobacco or alcohol use. On examination, her feet were cold, with ulcers on the first and second toes of the right foot. Peripheral pulses in the lower extremities were diminished, with bilaterally weak dorsalis pedis pulses, more pronounced on the right.Her autoimmune panel was positive for anti-nuclear, anti-dsDNA, and anti-centromere antibodies. Capillaroscopy and arterial Doppler ultrasound of the lower limbs were unremarkable. Her symptoms progressed despite multiple treatments, leading to gangrene of the first and second toes of the right foot. A positron emission tomography (PET) scan showed no evidence of vasculitis but revealed focal uptake in a 1.14 cm nodule in the right thyroid lobe. Fine-needle aspiration suggested PTC. She underwent thyroidectomy, and histopathology confirmed papillary carcinoma along with medium-sized vessels showing intimal thickening and marked luminal narrowing, consistent with vasculitis. At 18month followup, she demonstrated complete clinical resolution with no new ulcerations. CONCLUSION: Paraneoplastic acral vascular syndrome is a rare condition that resembles Raynaud's phenomenon and may improve after treatment of the associated cancer. This case emphasizes the importance of considering occult cancer in patients with unexplained digital ischemia.