Mercury is unique in that it is the only metal that is liquid at room temperature. It tends to form perfectly shaped minute spheres when in contact with air or wa- ter because of its high surface tension. Due to such a physical property, the injection of mercury into soft tis- sue produces a characteristic radiographic appearance.
We report a case of mercury foreign bodies within the soft tissue of the arm with imaging findings, including MRI findings.
Case Report
A 25-year-old male was referred to the department of
orthopedic surgery from an outside hospital due to the presence of foreign bodies in his right upper arm. The foreign bodies were first identified 2 years prior, while serving in the military. The subject claimed to have had no subjective symptoms, except for mild pain in the right upper arm during his tenure in the military. After discharge from military service, the patient visited our hospital to remove the foreign bodies. The radiographs revealed metallic foreign bodies scattered in his right upper arm (Fig. 1A). A physical examination revealed a palpable mass in the lateral aspect of the right upper arm without tenderness or swelling. Upon admission, the patient’s serum mercury level was 14.82 ug/dL (nor- mal level < 0.5 ug/dL). Otherwise, his laboratory exam results were within the normal range, except for a slight- ly elevated CRP value, as follows: WBC count = 6470, ESR = 9, CRP = 1.09. Despite this finding, the patient denied any history of exposure or self-administration of mercury.
Computed tomography (CT) and MRI were performed to assess the degree of mercury presence. The CT demonstrated two clusters of interspersed, high density foreign bodies in the muscle and periosteal areas of the humerus, with a beam hardening artifact (Fig. 1B). The
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MR Imaging Findings of Mercury Deposits in the Upper Arm: A Case Report1
Seung-Moon Joo, M.D., Jung-Ah Choi, M.D.1,2, Sung-Hwan Hong, M.D., Ja-Young Choi, M.D., Yeo Ju Kim, M.D.2, Joo Han Oh, M.D.3, Jin-Haeng Chung, M.D.4, Heung Sik Kang, M.D.1,2
1Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul, Korea
2Department of Radiology, Seoul National University Bundang Hospital, Seong Nam, Gyeongi-do, Korea
3Department of Orthopedic Surgery, Seoul National University Bundang Hospital, Seong Nam, Gyeongi-do, Korea
4Department of Pathology, Seoul National University Bundang Hospital, Seong Nam, Gyeongi-do, Korea
Received April 13, 2008 ; Accepted July 2, 2008
Address reprint requests to : Jung-Ah Choi, M.D., Department of Radiology, Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam-si, Gyeonggi-do 463-707, Korea
Tel. 82-31-787-7609 Fax. 82-31-787-4011 E-mail: [email protected]
The incidental injection of metallic mercury into soft tissue is a rare event in the gen- eral population. Mercury can produce local inflammation, abscesses, granuloma, and membranous fat necrosis. Herein, we report a rare case of soft tissue mercury deposits with imaging findings, including magnetic resonance (MR) imaging findings, located at the mercury droplet deposits which appear as signal voids on all sequences, with sur- rounding intermediate to high signal intensity on the T2- weighted image.
Index words :Mercury Foreign bodies
Magnetic resonance (MR) Soft tissue
Seung-Moon Joo, et al : MR Imaging Findings of Mercury Deposits in the Upper Arm
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A C
D E F
G H
Fig. 1. A 24-year-old male with soft tissue and periosteal mercury deposits in his right upper arm.
A. Oblique view of the right humerus demonstrates radiodense particles in the soft tissue and periosteal areas.
B. Axial scan on computed tomography shows multiple small radiodense particles scattered in the subcutaneous and periosteal areas.
C-F. Axial T1-weighted (C), T2-weighted (D), contrast enhanced T1-weighted fat suppressed axial (E) sagittal (F) images, mercury deposits are demonstrated as multifocal signal void lesions. For the T2-weighted image, the surrounding intermediate high signal intensity areas are visible. This is probably due to the foreign body reaction and edematous change around the mercury deposits.
G. The gross specimen shows multiple gray and silvery droplets of mercury.
H. A follow-up AP view of the right humerus after surgery shows a decreased bulk of radiodense materials in both the soft tissue and periosteal areas of the right upper arm.
B
MRI results revealed several dot-like signal voids in the periosteum of the humerus on an axial T1-weighted im- age (Fig. 1C). The axial T2-weighted image showed in- termediate signal intensity lesions surrounding the dot- like signal voids (Fig. 1D). The contrast-enhanced fat sat- urated T1-weighted image showed fairly intense en- hancement (Fig. 1E, F).
Four weeks after the patient’s initial visit, surgical ex- ploration revealed the mercury as small dark silver spheres (Fig. 1G). The histologic specimen revealed the formation of a microabscess and fibrosis with several sil- very globules (< 1 mm). Subsequent to the surgical pro- cedure, a follow-up radiograph revealed a decrease in the amount of radiodense particles in both the soft tissue and periosteal areas of the right upper arm (Fig. 1H).
The postoperative evaluation found that the patient did not complain of any specific symptoms, except for inter- mittent pain in his right upper arm.
Discussion
Mercury can be found in household items such as thermometers, barometers, commercial batteries, and fluorescent light bulbs. The subcutaneous or intra- venous injection of metallic mercury has been reported as accidental or deliberate. The latter has been described in psychiatric patients, suicide attempts, and in athletes hoping to increase their physical performance (1).
The injection of mercury in soft tissue produces local and systemic effects, which includes local inflamma- tion, abscesses, granulomas, and membranous fat necro- sis at local injection sites (2). The systemic absorption of mercury from soft tissue deposits, probably due to vas- cular or lymphatic spread, has been reported, and has been found to result in elevated blood mercury levels (3). Consistently, our patient also showed elevated blood mercury levels. Once injected, the mercury is converted into mercuric ions, which are then for the most part ex- creted in the urine, with a half-life of about 60 days (4).
However, the continuous release of mercury from the soft tissue deposits causes chronic exposure, as in our case.
In previous reports, the early excision of subcutaneous mercury deposits has been reported to effectively lower blood mercury concentrations (3). Krohn and co-work- ers suggest that the proper management of subcuta- neously injected metallic mercury includes four steps: a) excision of all readily accessible subcutaneous mercury, b) monitoring of the CNS and renal function for evi-
dence of mercurial toxicity, c) chelation therapy when there is such systemic toxicity, and d) psychiatric con- sultation and treatment when indicated (5).
Histologically, the mercury on hematoxylin and eosin preparations classically appears as spaces with adjacent or intraluminal dark grey to black opaque globules with surrounding microabscesses and granuloma formations (6). For the radiographs and CT, the small mercury glob- ules appeared as numerous small globular metallic opac- ities (7), which is consistent with our study. A sono- graphic examination found that the mercury globules appear as multiple small echogenic dots (8).
Monu et al. (9) described the MR imaging findings of soft-tissue granuloma, which are associated with the presence of foreign bodies. The granuloma appeared as a signal voids in an area of high signal intensity on T2- weighted images. These signal voids represent non- metallic foreign bodies such as wood and plastics. On the contrary, Lee et al. (10) described high signal intensi- ty foreign bodies, surrounded by mild high signal inten- sity granulomas on T1-weighted images. In this case, the foreign bodies represented oil droplets. In our case, the mercury droplets appeared as small globular signal void lesions for all sequences, similar to the nonmetallic for- eign bodies described in the previous report (9). The sig- nal voids are surrounded by an intermediate to high sig- nal intensity area on T2-weighted images with diffuse enhancement on enhanced images. This enhancement indicated the presence of the reaction to foreign bodies in the form of edema, which was proven by histologic specimen, since the mercury is a diamagnetic metal.
However, unlike the previously reported cases, no defi- nite soft tissue mass-like lesion, representing the granu- lomas, were observed in our case (9, 10).
Herein, we report a case of mercury injection in the soft tissue of the upper arm of our patient, which was di- agnosed by preoperative imaging (plain radiograph, CT, and MRI), and was attributed to the peculiar appearance of mercury, despite the patient’s denial of mercury ex- posure.
References
1. McFee RB, Caraccio TR. Intravenous mercury injection and inges- tion: clinical manifestations and management. J Toxicol Clin Toxicol 2001;39:733-738
2. Ramdial PK, Jogessar V, Dada MA. Membranous fat necrosis due to subcutaneous elemental mercury injections. Am J Forensic Med Pathol 1999;20:369-373
3. Soo YO, Wong CH, Griffith JF, Chan TY. Subcutaneous injection of metallic mercury. Hum Exp Toxicol 2003;22:345-348
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4. Ellenhorn, MJ, Schonwald S, Ordog G, Wassenberger J. Ellenhorn’s medical toxicology; Diagnosis and Treatment of Human poisoning. 2nd ed. Baltimore: Williams and Wilkins, 1997:1588-1600
5. Krohn IT, Solof A, Mobini J, Wagner DK. Subcutaneous injection of metallic mercury. JAMA 1980;243:548-549
6. Lupton GP, Kao GF, Johnson FB, Graham JH, Helwig EB.
Cutaneous mercury granuloma: a clinicopathologic study and re- view of the literature. J Am Acad Dermatol 1985;12:296-303 7. Hunter TB, Taljanovic MS. Foreign Bodies. Radiographics
2003;23:731-757
8. Romero M, Bargallo X, Lo pez-Quin˜ones MT, Bun˜esch L, Bianchi L, Bru C. Sonography of a mercury foreign body in the hand. J Ultrasound Med 2004;23:711-714
9. Monu JU, McManus CM, Ward WG, Haygood TM, Pope TL Jr, Bohrer SP. Soft-tissue masses caused by long-standing foreign bod- ies in the extremities: MR imaging findings. AJR Am J Roentgenol 1995;165:395-397
10. Lee SY, Lee NH, Chung MJ, Chung GH. Foreign-body granuloma caused by dispersed oil droplets simulating subcutaneous fat tissue on MR images. AJR Am J Roentgenol 2004;182:1090-1091
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대한영상의학회지 2008;59:111-114
상완연부조직에 수은침착의 자기공명영상소견1
1서울대학교병원 영상의학과
2분당서울대학교병원 영상의학과
3분당서울대학교병원 정형외과
4분당서울대학교병원 병리과
주승문・최정아1, 2・홍성환・최자영・김여주2・오주한3・정진행4・강흥식1,2
연부조직에 직접 주입된 수은 이물은 드물며, 염증, 농양, 육아종 및 지방괴사 등을 일으킬 수 있다. 몇몇 문헌에 서 단순촬영과 CT, 초음파 소견을 보고하였다. 저자들은 조직학적으로 증명된 연부조직 내 수은 이물의 자기공명 영상 소견을 보고한다.
