Histological changes of parathyroid adenoma after percutaneous injection of ethanol L.T.C.CHOW, C.METREWELI*, W.W.K.KING , N.L.S.TANG & P.W.ALLEN Departments of Anatomical and Cellular Pathology, *Diagnostic Radiology and Organ Imaging, Surgery and Chemical Pathology, Prince of Wales Hospital, Hong Kong Date of submission 6 June 1996 Accepted for publication 1 July 1996 Keywords: parathyroid, adenoma, alcohol injection Introduction The availability of high-resolution ultrasonography has allowed visualization of enlarged parathyroid glands to be achieved in a relatively easy and non-invasive manner. Furthermore, a reliable histological diagnosis can often be secured by the application of ultrasound- guided fine-needle aspiration biopsy provided that sufficient amount of tissue is obtained 1 . The ability to place needles precisely in enlarged parathyroid glands has opened new avenues to the management of these parathyroid lesions. Indeed, many recent reports sug- gested that ultrasound-guided percutaneous ethanol injection of enlarged parathyroid lesions might prove to be a useful alternative to surgery in the treatment of hyperparathyroidism 23 . The histological changes in the parathyroid gland following such ethanol injection, however, have not been analyzed and are mentioned only very briefly in some of these reports 23 . In this case report, we describe in detail the histological changes of a parathyroid adenoma after ethanol injection; the significance of these changes is discussed. Case report A 66-year-old man was referred to our hospital because of weakness of both lower limbs, associated with polyuria and polydypsia for the past six months. Investigation showed biochemical and radiological features of hyperparathyroidism; the ionised calcium was 1.59 mmol/l (normal range of 1.13–1.32 mmol/l) and phosphate was 0.55 mmol/l (normal range of 0.82–1.40 mmol/l). Serum parathyroid hormone was 210 pmol/l (normal range of 1.2–5.7 pmol/l). Ultra- sonography revealed a nodule, 1 5 2 5 cm, in the posterior aspect of the inferior pole of the right lobe of the thyroid, and ultrasound-guided fine-needle biopsy showed features consistent with a parathyroid adenoma (Figure 1); the other parathyroid glands were not visualized. In view of the patient’s long standing poor respiratory function and the high risk for general anaesthesia, percutaneous ethanol injection of the parathyroid adenoma was performed. Under ultrasound guidance, 1 ml of absolute ethanol was injected into the para- thyroid adenoma. A total of three injections was given, at intervals of 8 and 24 days. Both the ionised calcium and parathyroid hormone decreased but remained persis- tently elevated, measuring 1.34 mmol/l and 178 pmol/l, respectively, 50 days after ethanol injection. Resection of the parathyroid adenoma was thus performed under local anaesthesia 80 days after ethanol injection. At operation, the parathyroid adenoma was removed Histopathology 1997, 30, 87–89 1997 Blackwell Science Limited. Figure 1. The fine-needle biopsy of the parathyroid adenoma showed closely packed parathyroid cells supported in a fibrovascular stroma devoid of adipose cells. Address for correspondence: Dr Louis T.C.Chow, Department of Anatomical and Cellular Pathology, Prince of Wales Hospital, 30–32, Ngan Shing Street, Shatin, Hong Kong.