Medical Image of the Week: Elemental Mercury Poisoning

Figure 1. Panel A: Abdominal x-ray showing radiopaque matter. Panel B: Repeat x-ray after colonoscopy.

A 34-year-old woman presented to the Emergency department with abdominal pain after ingestion of an unknown liquid that family felt might be poisonous. The patient had a past history of prior suicide attempts, as well as a history of polysubstance and alcohol abuse. The patient was confused, tangential and a difficult historian. The patient had a heart rate of 72, was normotensive, and had an oxygen saturation of 100% on room air.  She was confused and answered questions intermittently. The remainder of her physical examination including her neurological exam was normal. The initial serum chemistry, anion gap, lactate, liver function tests were normal. Urine drug screen was positive for benzodiazepines, for which the patient was prescribed. An abdominal x-ray was performed showing a radiopaque substance in the abdomen (Figure 1A). It was eventually determined she ingested elemental mercury. Blood levels were elevated, and she did eventually have hematochezia. Colonoscopy was performed which removed some of the metallic liquid mercury (Figure 1B).

Mercury in any form is poisonous, with mercury toxicity most commonly affecting the neurologic, gastrointestinal (GI) and renal organ systems (1). Poisoning can result from mercury vapor inhalation, mercury ingestion, mercury injection, and absorption of mercury through the skin.

Elemental mercury is poorly absorbed after ingestion but easily vaporizes at room temperature and is well absorbed (80%) through inhalation. Once absorbed elemental mercury is mostly converted to an inorganic divalent or mercuric form by catalase in the erythrocytes. This inorganic form has similar properties to inorganic mercury (e.g., poor lipid solubility, limited permeability to the blood-brain barrier, and excretion in feces).

Treatment of mercury toxicity consists of removal of the patient from the source of exposure, supportive care, and chelation therapy. Our patient had limited symptoms, and for this reason, chelation therapy was not performed. She made an uneventful recovery after discharge to psychiatry. Her blood levels eventually returned to normal in a few months.

Michel A. Boivin, MD

Pulmonary/Critical Care/Sleep Medicine

Department of Internal Medicine

University of New Mexico

Albuquerque, NM USA

Reference

1. Olson DA. Mercury poisoning. Medscape. August 14, 2017. Available at: https://emedicine.medscape.com/article/1175560-overview (accessed 5/22/18).

Cite as: Boivin M. Medical image of the week: Elemental mercury poisoning. Southwest J Pulm Crit Care. 2018;16(5):287-8. doi: https://doi.org/10.13175/swjpcc067-18 PDF 

Medical Image of the Week: Thoracic Splenosis

Figure 1. A: Axial CT of the chest without intravenous contrast demonstrates a cluster of soft tissue nodules adjacent to the left posterior hemi-diaphragm (blue arrows). B: Axial CT of the chest without intravenous contrast demonstrates absence of the spleen and a surgical clip (blue arrow) consistent with a prior splenectomy.

Figure 2. Fused technetium 99m-label sulfur colloid uptake study and axial CT of the chest without intravenous contrast demonstrates uptake of radiotracer in the previously seen soft tissue nodules adjacent to the posterior aspect of the left hemi-diaphragm (red arrows) which confirms the diagnosis of thoracic splenosis.

A 38-year-old man with a history of a motor vehicle collision about 20 years prior to presentation which resulted in multiple left-sided rib fractures, a left-sided pneumothorax requiring chest tube placement, and a high-grade splenic laceration necessitating an emergent splenectomy that presents to outpatient pulmonary clinic for evaluation of pulmonary nodules at the request of his primary care physician. He is asymptomatic. He has a 20-pack-year of smoking history and currently smokes 6 cigarettes per day. He denies any significant exposures or recent infections. He has a family history significant for heart disease and depression, but no history of malignancy. His vital signs and physical examination are normal. He had a CT of the chest performed with representative images from the study shown in Figure 1.

A nuclear medicine scan was subsequently requested which demonstrated uptake of the technetium 99m-labeled sulfur colloid in the soft tissue nodules adjacent to left hemi-diaphragm (Figure 2) confirming the diagnosis of thoracic splenosis. No further treatment or diagnostic work up was required.

Splenosis is defined as auto-transplantation of splenic tissue following traumatic or surgical disruption of the spleen. Splenosis usually occurs in the abdomen, most commonly in the left upper quadrant (1,2). However, with disruption of the diaphragm in the setting of trauma, splenic tissue can migrate into the thoracic cavity, and most often settles in the inferior, posterior left pleural space (as in our patient).  The diagnosis of thoracic splenosis should be suspected when one sees left basilar pleural nodules/masses in the setting of a previous trauma necessitating a splenectomy. A technetium 99m-labeled sulfur colloid study will demonstrate uptake of the radiotracer in the auto-transplanted splenic tissue as this radiotracer has a strong affinity for tissue arising from the reticuloendothelial system.

Gregory Gardner MD¹, Kevin Breen¹, Tammer Elaini MD², and Tiffany Ynosencio MD²

¹Department of Internal Medicine

²Division of Pulmonary, Critical Care, Allergy and Sleep

University of Arizona College of Medicine

Tucson, AZ USA

References

1. Khosravi MR, Margulies DR, Alsabeh R, Nissen N, Phillips EH, Morgenstern L. Consider the diagnosis of splenosis for soft tissue masses long after any splenic injury. Am Surg. 2004 Nov;70(11):967-70. [PubMed]
2. Rosado-de-Christenson ML, Abbott GF. Diagnostic Imaging: Chest. 2^nd edition. Philadelphia, PA: Lippincott Williams & Wilkins; 2012: 30-1.

Cite as: Gardner G, Breen K, Elaini T, Ynosencio T. Medical image of the week: thoracic splenosis. Southwest J Pulm Crit Care. 2018;16(5):285-6. doi: https://doi.org/10.13175/swjpcc066-18 PDF