Endocrine Abstracts

A 64 year-old Eritrean female presented with a toxic multinodular goitre. Free T4 was 37.8 pmol/L, TSH <0.01 mU/L, and a neck ultrasound scan showed areas of calcification. A Technetium scan revealed an increased tracer uptake of 9.8% with a right-sided dominant nodule and photopenic areas. An ablative dose of radio-iodine was administered as she did not tolerate thionamide therapy.

Six months later the patient reported intermittent hoarseness of voice. She was clinically euthyroid and a 6×8 cm right-sided hard nodule was palpable, as well as an associated submandibular lymph node. Fine needle aspiration yielded benign cytology. A neck CT showed leftward displacement of the trachea and widespread coarse calcification within the thyroid. Moreover, a generalised abnormal bone texture was noted, only sparing the mandible. Small lytic areas were seen and considered suspicious for neoplastic involvement. Subsequent investigations for malignancy were negative, including a screen for multiple myeloma.

Haematological investigations showed a moderate thrombocytopenia with enlarged forms, a low-normal haemoglobin and WBC, and an ESR of 48 mm/h. Biochemical analysis revealed normal renal function and alkaline phosphatase but low serum calcium and phosphate. Parathyroid hormone was 26.1 pmol/L (N.R. 1.1–6.9), and the 25-hydroxy-vitamin D level was below the detection threshold. Bone scintigraphy showed an unusual cortical/periosteal pattern of increased uptake in the femora.

A diagnosis of osteitis fibrosa cystica was made, due to secondary hyperparathyroidism consequent to severe and prolonged vitamin D deficiency. The PTH-mediated increase in bone turnover can lead to the virtually diagnostic appearances of subperiosteal, subcortical and endosteal bone resorption. Brown tumours are well-defined lesions of the axial or appendicular skeleton and consist of fibrous tissue with an abundance of giant cells. Extra-osseus calcification is well documented in secondary hyperparathyroidism. Severe vitamin D deficiency can cause reversible myelofibrosis with a resulting pancytopenia.