CORRESPONDENCE A B L A T I O N OF M E D I A S T I N A L P A R A T H Y R O I D A D E N O M A S SIR - The two patients treated by Reidy and colleagues  illustrate how parathyroid ablation, a technique pioneered by Dr John D o p p m a n at the National Institutes of Health in the United States, can be used to obviate the necessity for major surgery in selected patients with mediastinal parathyroid adenomas . However, the use of intravascular ethanol for parathyroid ablation requires both caution and precision on the part of the angiographer. Parathyroid glands in the anterior mediastinum, such as those ablated by Reidy and colleagues, derive their blood supply from a thymic branch of the internal m a m m a r y artery. This branch also supplies the thymus and much of the surrounding anterior mediastinum. When parathyroid adenomas are ablated with ionic contrast material injected into this thymic branch, diffuse enhancement of the anterior mediastinum is visible on C T scans obtained immediately after the procedure, and oedema of the anterior mediastinal contents is evident on CT scans obtained 24 h after ablation . Ethanol causes destruction of all tissue with which it comes in contact. As Reidy and colleagues stress, if ethanol is used to ablate mediastinal glands it is essential that the catheter tip be placed distal to all other anterior mediastinal branches, and that reflux be avoided. The marked ablative ability of ethanol is a drawback in this situation, while 'mildly toxic' [l] contrast material provides a greater margin of safety. Since parathyroid ablation is rarely performed, very few radiologists are able to accumulate any degree of experience with the procedure. The margin of safety provided by ionic contrast material is therefore an asset, not a liability. Selection of patients for angiographic ablation requires consideration of a potential complication not discussed by Reidy and colleagues. If the patient has only one remaining functioning parathyroid gland, and this gland is ablated, the patient will be rendered permanently hypoparathyroid. This risk is present even if no parathyroid glands were resected during previous surgical exploration. Normal parathyroid glands may undergo infarction as a result of biopsy if the incision transects the solitary artery which supplies each gland. The resultant hypoparathyroidism can cause substantial morbidity over the life-span of a patient who first develops it at age 20. Surgical resection avoids this complication, since a portion of the resected gland m a y be either autotransplanted at the time of surgery or frozen for possible future autotransplantation [4,5]. For this reason, at the National Institutes of Health we reserve angiographic ablation for patients with mediastinal lesions who are elderly or poor candidates for surgery. We would not have attempted ablation in either of the young patients reported by Reidy and colleagues . We also do not attempt ablation of glands in the neck because of the higher complication rate of ablation in this area and because these lesions, if necessary, can be removed through a small incision under local anesthesia . The algorithm we use to guide therapy and the rationale behind it have been described in detail elsewhere . D. L. M I L L E R
Diagnostic Radiology Department Building 10, Room 1C660 National Institutes of Health Bethesda MD 20892 USA
1 Reidy JF, Ryan PJ, Fogelman I, Lewis JL. Ablation of mediastinal parathyroid adenomas by superselective embolization of the internal m a m m a r y artery with alcohol. Clinical Radiology 1993;47:170-173. 2 D o p p m a n JL, Marx SJ, Spiegel AM, Mallette LE, Wolfe D R , Aurbach G D et al. Treatment of hyperparathyroidism by percutaneous embolization of a mediastinal adenoma. Radiology 1975;115:37 42. 3 Miller DL, D o p p m a n JL, C h a n g R, Simmons JT, O'Leary TJ, Norton JA et al. Angiographic ablation of parathyroid adenomas: lessons from a 10-year experience. Radiology 1987;165:601 607. 4 Senapati A, Y o u n g AE. Parathyroid autotransplantation. British Journal of Surgery 1990;77:1171 1174. 5 Brunt LM, Sicard GA. Current status of parathyroid autotransplantation. Seminars in Surgery and Oncology 1990;6:115-121. 6 Miller DL. Preoperative localization and interventional treatment of parathyroid tumors: When and how? World Journal of Surgery 1"991;15:706 715.
SIR- We were very interested in Dr Miller's comments, especially in view of the N I H ' s considerable experience of ablation of mediastinal
parathyroid adenomas. We entirely agree that ablation of these rare adenomas, either by contrast media or alcohol is a specialized technique and certainly not one for the occasional angiographer. Their group over m a n y years used 'mildly toxic' ionic contrast media in large amounts (average 50 ml). In order to inject such volumes they have preferred to wedge large catheters rather than being more selective using smaller co-axial catheters. It is thus not surprising in their series that chest pain was c o m m o n both during and after the procedure and that of the 13 who had C T scans, 24 h later, staining was demonstrated in nine. Improvements in co-axial catheters such as the tracker catheter that we used, now mean that it is possible to achieve a more superselective catheter placement without wedging. Injection of very small a m o u n t s (less than 1 ml) of alcohol will then produce very effective but precise tissue ablation. We would suggest that this is more controlled than using much larger volumes of less toxic contrast media and it would appear to be well tolerated by patients. Mixing the alcohol with oily Lipiodol m a y have some advantages and the lateral chest X-ray on our Case 2 certainly showed the Lipiodol localized to the adenoma. Of the 24 patients ablated by the N I H group, long-term normocalcaemia occurred in 19 and in two persistent hypocalcaemia resulted. Hypoparathyroidism has been an accepted complication following surgery. We did not discuss autotransplantation at the same time as surgery or cryopreservation of the parathyroid for future transplantation, l understand that this is no longer widely practised and certainly was not a consideration in our patients. We also are not advocating transcatheter ablation of adenomas in the neck. There is little in the literature on such cases but I am not aware that significant complications have resulted. I see no reason why, if superselective catheterization can be achieved, that in selected patients, such adenomas could not also be ablated. This would be more controlled than direct injection of alcohol by a needle into the adenomas that have been advocated by others. J. F. R E I D Y
Department of Radiology Guy's Hospital St Thomas' Street London SEI 9RT
T E S T I C U L A R M I C R O L I T H I A S I S AND S E M I N O M A SIR--We read with interest the recent case report 'The ultrasound appearances of testicular microlithiasis ('snow storm' testis): a case complicated by testicular seminoma' , and wish to comment further on the association between testicular microlithiasis (TM) and neoplasms of the testis. Several articles regarding this association [2 5] appeared more or less simultaneously with the case published in your journal . We described a series of I 1 patients with T M , two of w h o m had coexistent seminoma . In two other series, 40% (17 of 42) and 45% (5 of 11) of patients with TM had coexistent testicular neoplasms [3,4]. Germ cell turnouts and seminoma are the most c o m m o n histologic types of testicular neoplasm associated with T M . T M is also associated with cryptorchidism, delayed testicular descent and subfertility/infertility . Accurate estimates of the relative risk of testicular neoplasm in patients with T M are not available, as the denominator (the prevalence of T M in asymptomatic men) is unknown. No large scale sonographic screening studies of asymptomatic men have been reported. TM is usually discovered as an incidental finding at sonographic examination performed to evaluate patients with symptoms or signs of intrascrotal abnormality, therefore a strong selection bias is present which would falsely increase the apparent prevalence of neoplasm in patients with TM. We believe that the occurrence of testicular neoplasm in patients with T M is related to the probable underlying cause of T M , namely atrophy and degeneration of the testicular tissue . The most c o m m o n associations of T M (cryptorchidism, delayed testicular descent and subfertility/infertility) are all associated with increased risk of testicular neoplasm. Despite the absence of solid statistical evidence, we believe that the risk of testicular neoplasms in patients with T M is significant. We recommend that patients with T M undergo clinical and/or sonographic examination of the testis at 6 to 12 m o n t h intervals to screen for the development of testicular neoplasm. D. L. J A N Z E N J. R. M A T H I E S O N
Department of Radiology University of British Columbia and St Paul~ Hospital 1081 Burrard Street Vancouver, BC Canada V6Z 1 Y6
1 Roberts ISD, Loughran CF. Case report: the ultrasound appearances of testicular microlithiasis ('snow storm' testis): a case complicated by testicular seminoma. Clinical Radiology 1993;47:65-67. 2 Janzen DL, Mathieson JR, M a r s h Jl, Cooperberg PL, del Rio P, Golding RH, Rifkin MD. Testicular microlithiasis: sonographic and clinical features. American Journal of Roentgenology 1992; 158:1057 1060. 3 Backus ML, Mack LA, King BF Jr, Middleton WD, Winter TC Ili, True LD. Testicular microlithiasis: imaging appearances and pathologic correlation. Radiology 1992;185(P):238 239. 4 Hobarth K, Susani M, Szabo N, Kratzik C. Incidence of testicular microlithiasis. Urology 1992;40:464-467. 5. Kutcher R, RosenbJatt R, Kremer S. Testicular microlithiasis. American JournalofRoentgenology 1992;159:1129. 6 Kragel PJ. Delvecchio D, Orlando R, Garvin DF. Ultrasonographic findings of testicular microlithiasis associated with intratubular germ cell neoplasia. Urology 1991;37:66 68. 7 Vegni-Talluri M, Bigliardi E, Vanni M G , Tota G. Testicular microliths: their origins and structure. Journal of Urology 1980;124:105 111.
M A M M O G R A P H I C A C C U R A C Y A N D P A T I E N T AGE SIR I read with interest the paper by Davies et al. [I]. Their conclusion that m a m m o g r a p h y is of equal accuracy in young and older women is in sharp contrast to severaLrecent publications, including the one they cite themselves in the paper [2-5]. While agreeing that age should not be a bar to diagnostic clinical m a m m o g r a p h y , I am not at all sure that the conclusion reached by Davies et al. can be justified from the design and results of their paper. - -
(1) The authors' conclusion refers to women requiring breast biopsy on clinical grounds. Yet their study included forty (13%) women with non-palpable screen detected lesions. By definition, these lesions must have been visible on m a m m o g r a p h y . (2) However, they do state that results of their study cannot be applied to screening m a m m o g r a p h y [6,7]. This ought to have been stated more clearly than merely noting 'extrapolation to the screening population should be made with caution'. (3) The patient's age was concealed to avoid bias. However, it is often possible to guess a w o m a n ' s age from looking at her m a m m o g r a m young women usually have "dense' breasts . (4) Clinical information was concealed from the reader at the time of m a m m o g r a p h y review. In real life, the radiologist would have access to this information and it would undoubtedly influence his/her assessment of the m a m m o g r a m s . (5) Conversely, although clinical information was not provided, it was known to the reviewer that every w o m a n in the study had gone on to breast surgery. The reviewer was therefore aware that there must have been a clinical and/or radiological abnormality suspicious enough to warrant biopsy. In a true reporting situation such hindsight would obviously not be available. In fact, most patients who have symptomatic diagnostic m a m m o g r a p h y do not end up having a biopsy. Therefore, the specificity in this study does not necessarily correspond to the true specificity of symptomatic diagnostic m a m m o g r a p h y . (6) It appears that there was no attempt to ensure that the area of "abnormality' identified in each m a m m o g r a m in the study matched the area of the breast which was biopsied. It is therefore uncertain whether the two areas were the same in every case. (7) The authors state that their study reflects that 'age and menopausal status are the major factors for breast cancer'. In fact, they do not seem to have established the true menopausal status of the women in the study. Furthermore, the reference they quote  does not actually state that menopausal status is a major risk factor independent of age. (8) When m a m m o g r a p h y fails to demonstrate a clinically palpable abnormality, ultrasound is often supplemented to increase the specificity of the diagnostic process. Measuring the specificity of m a m m o g r a p h y alone in these cases has little practical value. (9) In patients who present with an obvious breast .cancer, the main reason for doing m a m m o g r a p h y is to assess the size and extent of the
lesion, search for multi-focal disease and confirm that the contralateral breast is normal . A. M. A. H U S I E N
Breast Screening Unit Kettering General Hospital Rothwell Road Kettering Northants NNI6 8UZ
1 Davies RJ, A ' H e r n RP, Parsons CA, Moskovic EC. M a m m o graphic accuracy and patient age: a study o f 297 patients undergoing breast biopsy. Clinical Radiology 1993;47:23-25. 2 Yelland A, G r a h a m M D , Trott PA, Ford HT, Coombes RC, Gazet JC, Poison NG. Diagnosing breast carcinoma in young women. British Medical Journal 1991;302:618-620. 3 G r u n b a c h Y, Nguyen HT. M a m m o g r a p h y in younger women. Current Opinion in Radiology 199I;3:602-610. 4 Arablinskii VM, Ostrovskaia IM, Shipulo MG, Lisachenko IV. Ul'trazvukovaia i rentgenologicheskaia diagnostika uzlovykh obrazovanil molochnykh zhelez u zhenscbeh in molodogo vozrastia. Vestnik Rentgenologii Radiologii 1991;2:65 70. 5 Ciatto S, Cecchini S, del-Turco M R , Grazzini G, Iossa A, Bartoli D. Referral policy and positive predictive value of call for surgical biopsy in the Florence Breast Cancer Screening Program. Journal of Clinical Epidemiotogy 1990;43:419-423. 6 Forrest P. Breast cancer screening. Report to the health ministers of England, Wales, Scotland and Northern Ireland. London: HMSO, 1986. 7 Editorial: Breast cancer screening in women under 50. Lancet 1991;337:1575-1576. 8 Wolfe JN. Breast parenchymal patterns and their changes with age. Radiology 1976;121:545 552. 9 Teixidor HS, K a y a n E. Combined mammographic-sonographic evaluation o f breast masses. American Journal o f Roentgenology 1977; 128:409-4 17. 10 Warwick D J, Smallwood JA, Guyer PB, Dewbury K C , Taylor I. Ultrasound m a m m o g r a p h y in the management of breast cancer. British Journal o f Surgery I988;75:243-245. 11 Catarzi S, Guisepetti G M , Rizzatto G, Rosseli-Del-Turco M. Studio multicentrico per la valutazione delrefficacia diagnostica della mammografia e dell'ecografia nelle neoplsie m a m m a r i e non palpaili. Radiol Med Torino 1992;84:193 197. 12 Lawrence W, Bassett M D , Richard H, Gold M D . Breast cancer detection. Orlando: Grune & Stratton, 1987:161-162. 13 Egan RL. Breast imaging. Philadelphia: WB Saunders Co, 1988:604-605. SIR We thank Dr Husein for the interest he has shown in our paper  and note that he agrees with our conclusion that m a m m o g r a p h y should not be withheld on age grounds in patients with symptomatic breast disease. In answer to some of the specific points Dr Husein raises: the design of the study was dictated by the need to judge m a m m o g r a p h i c accuracy against the gold standard of histology. Ethical considerations therefore restrict patient selection to those who had either clinical or imagingdetected abnormalities sufficient to warrant biopsy. The primary object of this paper was to compare mammographic accuracy with patient age. By keeping the criteria for inclusion into the study the same for different patient age-groups, and with blind review o f the m a m m o g r a m s , we maintain that the results are entirely valid for this albeit selected group of patients. We have specified that extrapolation to the screening population should be made with caution. Guessing the patient's age from the m a m m o g r a m is unreliable since a substantial proportion of women under 50 have fatty replacement of the breast tissue and an even larger number of those over 50 retain dense glandular tissue, especially those on hormone replacement. -
R. J. DAVIES E. C. M O S K O V I C
Department o f Diagnostic Radiology Royal Marsden Hospital Fulham Road London SW3 6JJ
Reference 1 Davies RJ, A ' H e r n RP, Parsons CA, Moskovic EC. M a m m o g r a p h i c accuracy and patient age: a study o f 297 patients undergoing breast biopsy. Clinical Radiology 1993;47:23 25.