Giant mixed solid cystic parathyroid adenoma – Diagnostic and surgical challenges

Giant parathyroid adenomas of cystic or mixed type are rare lesions that may mimic systemic or metabolic conditions such as gout and other musculoskeletal disorders. Overlap of symptoms often results in diagnostic delays and pose surgical challenges. We report a case of woman in her fifties who presented with two-year history of generalised weakness and joint pain, initially treated as gout. She later developed a progressive painful neck swelling and intermittent flank pain. Laboratory evaluation revealed severe hypercalcemia (15.5 mg/dL), markedly elevated parathyroid hormone (1528 pg/mL), and renal dysfunction. Ultrasonography demonstrated a large mixed solid cystic lesion posterior to the left thyroid lobe, and Technetium -99 Sestamibi scan confirmed a left upper parathyroid adenoma. Intraoperatively, a giant cystic mass (6.5 x 4x 4 cm) densely adherent to the left thyroid lobe was found, requiring left hemithyroidectomy for complete excision. Histopathology confirmed a mixed solid cystic parathyroid adenoma without malignancy. The patient developed transient post operative hypocalcaemia, which was managed conservatively, and recovered uneventfully. This case underscores the importance of considering giant parathyroid adenomas in patients with hypercalcaemia and atypical local and systemic symptoms, as well as the need of careful surgical planning in managing giant or adherent parathyroid tumours.