Parathyroid Carcinoma: Atypical Presentation, Diagnosed on Ultrasound: A Case Report

Abstract

Parathyroid Carcinoma is a very rare condition and with a very few cases published in literature. It is often suspected and diagnosed clinically in cases of hyperparathyroidism, when there is are very highly elevated serum calcium levels, along with significantly raised serum PTH levels, and the patient is quite symptomatic. We report here a case where the serum calcium levels and PTH, both were not so high, hence the diagnosis was not thought of clinically, but only suggested by ultrasound imaging. The typical ultrasound diagnostic findings of a likely malignant parathyroid mass, prompted the surgeon to go for Hemi thyroidectomy along with, instead of simple parathyroidectomy. Biopsy came as Parathyroid Carcinoma. Case Report and literature review. A 66 year old male, presented with complaints of weight loss, back pain in medical oncology. CECT Spine showed multiple lytic lesions in D10, D12, and L4. Differential Diagnosis of metastasis or multiple myeloma was given. PET –CT showed metabolically active lesions in bones and posterior to left thyroid. Bone marrow biopsy was negative for both myeloma and metastasis. Serum parathormone and serum calcium levels were then suggested. Serum Calcium was 10.8mg/dL. Serum PTH was 947.0 pg/mL & 25– OH Vitamin D 16.3 g/mL. Sestamibi showed left inferior parathyroid adenoma. With an endocrinology diagnosis of primary Hyperparathyroidism and with a left inferior parathyroid adenoma, patient was referred to Head and neck oncosurgery for parathyroidectomy. ULTRASOUND: showed a heterogeneous hypoechoic solid cystic lobulated mass lesion, measuring 38 x21 x29 mm, volume 11.2 cc below the lower pole of left thyroid gland. The margins of the lesion appeared to be in close proximity to the thyroid and adjoining structures. It showed amorphous calcifications and heterogeneous increased vascularity, suggestive of parathyroid mass, likely carcinomaSURGICAL FINDINGS: Left Thyroid lobectomy with left parathyroidectomy was done. The parathyroid gland (30x30x20 mm) was firm to hard at surgery, and adherent to the thyroid. HISTOPATHOLOGY: Parathyroid tissue showed nuclear polymorphism, with large nucleus and prominent nucleoli. Broad fibrous septa are seen. Mitosis1-2/hpf. Capsular invasion is seen as well as invasion in the surrounding soft tissue and parathyroid tissue. Vascular invasion is seen. On IHC: Ki67:2% A pre-operative suggestion of parathyroid carcinoma instead of parathyroid adenoma improved patient counselling for a planned hemi thyroidectomy along with left parathyroidectomy and resulted in better management of the patient. A dedicated high resolution Colour Doppler Ultrasound is a valuable tool for localization and characterization of parathyroid nodules in all cases of raised serum PTH and must be utilized in all cases along with other imaging modalities.