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The Case Files is an anecdotal collection of emergency medicine cases to enable physicians and researchers to find clinically important information on unusual conditions.

Case reports should focus on:

    • Unusual side effects or adverse interactions.
    • Unusual presentations of a disease.
    • Presentations of new and emerging diseases, including new street drugs.
    • Findings that shed new light on a disease or an adverse effect.

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Wednesday, March 13, 2019


A 2-year-old girl was playing outside when she spotted a furry caterpillar. Like her stuffed animals, it was fluffy and had long hair. She let the insect crawl on her legs, but then suddenly screamed in pain. Her parents brought her to the ED, though she was no longer in distress by the time she arrived.

The patient had a large urticarial lesion on her inner right thigh and a smaller one on her left thigh. (Photo.) There were no puncture wounds, bite marks, or barbs visible or palpable. Her vital signs and physical exam were within normal limits. The patient's father had captured the culprit in an empty pill bottle and brought it to the ED for identification. (Photo.)

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Urticarial lesions prompting ED presentation.

Megalopyge opercularis, known as the puss caterpillar, woolly slug, possum bug, or perrito (Spanish for little dog), is a moth found all over the United States. (United States Department of Agriculture. Department Circular 288. 1923; The larval caterpillar form has venomous long hair-like setae protruding from its body. (van Nieukerken EJ, et al. Order Lepidoptera Linnaeus, 1758. In: Animal Biodiversity: An Outline of Higher-Level Classification and Survey of Taxonomic Richness, Zhang ZQ (Ed), Magnolia Press: Auckland 2011. Vol 3148, p. 212.) Its fluffy, stuffed animal-like appearance is often confused, especially by children, for an innocuous caterpillar.

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Adverse reactions after contact with poisonous or barbed caterpillars, moths, or butterflies are classified as lepidopterism. (MMWR Morb Mortal Wkly Rep 1990;39[13]:219; This encompasses a group of symptoms varying in severity that includes sting reactions, hypersensitivity reactions, and lonomism, the most severe form. Most stinging and hypersensitivity reactions are self-limiting and require only minor supportive care with analgesics and antihistamines, but lonomism is a bleeding diathesis that has a much more serious presentation.

This bleeding diathesis activates prothrombin with simultaneous degradation of several important clotting factors, including fibrin, fibrinogen, and factor XIII. (Thromb Res 2004;113[2]:147; Thromb Res 2001;102[5]:437.) Patients with lonomism present with excruciating localized pain at the envenomation site, vague neurological symptoms such as dizziness or altered mental status, generalized abdominal pain, and evidence of bleeding. It can be lethal in up to four percent of patients and requires inpatient supportive care, hematology consultation, and possibly serum immunoglobulin and dialysis if symptoms of acute renal failure develop. (Thromb Res 2004;113[2]:147.)

Megalopyge opercularis, fortunately for our patient, is only capable of sting reactions and has not been reported to cause hypersensitivity reactions or lonomism. (JAMA 1961;175[13]:1155.) The identity of the organism responsible for a bite or sting can dictate expectations, outcome, and therapeutic management. The mild, self-resolving symptoms, relatively benign physical exam, and correct identification of the organism reassured the patient and her family. Minimal supportive care, such as removing any potentially retained barbs with adhesive tape and giving NSAIDs, is sufficient treatment. A final take-home point: It is best to stay away from unknown insects, even ones that may have a friendly appearance.

Dr. Lynch is a junior resident, and Dr. Supino is the associate program director of the emergency medicine residency at Jackson Health System/University of Miami.

Tuesday, February 26, 2019


The progressive suprapubic pain was a cunning symptom.

The 38-year-old man had had five days of that pain and dysuria. By the time he presented to our ED, his pain had spread to the right lower quadrant as well. He had a history of diverticulitis after a laparoscopic left hemicolectomy four years earlier.

He reported no fevers, but complained of nausea and diarrhea. He was afebrile at 36.8°C with a pulse of 76 bpm. All other vital signs were normal. Physical exam was significant for suprapubic pain and right lower quadrant tenderness to palpation without rebound, guarding, or distention.

His workup revealed a normal white blood cell count of 4.2, as well as a normal basic chemistry and urinalysis. A CT of the abdomen and pelvis with intravenous contrast showed a dilated appendix tip measuring 12 mm with mucosal enhancement and fat stranding. The appendix was elongated and overlying the bladder.

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Computed tomography of the abdomen and pelvis with intravenous contrast. The yellow arrows show the appendix coursing through the lower abdomen and overlying the bladder.

Our patient was diagnosed with acute appendicitis. He was given antibiotics, intravenous fluids, kept NPO, and admitted to the surgical team. He underwent uncomplicated laparoscopic appendectomy and was discharged the next day.

Suprapubic pain and right lower quadrant pain are typical chief complaints in the emergency department, but it is important to keep a broad differential diagnosis when evaluating patients. In acute appendicitis, migrating right lower quadrant pain, fever, anorexia, nausea, and vomiting are unreliable, occurring consistently in only about half of cases. (Hong Kong Med J 2000; 6[3]:254;

When considering additional diagnoses, it is important to recall anatomical structures near where the pain is reported and to be mindful of variations in appendiceal sizes and locations. The appendix in the retrocecal position can cause inflammation of the retroperitoneal organs, mimicking biliary colic or gastroenteritis. (Adv J Emerg Med 2018;2[2]:e21; A perforated appendix can cause fistula formation to the anterior abdominal wall and present as a palpable mass. (BMJ Case Rep 2016 Nov 10; Our patient's appendix was elongated and overlying the bladder, resulting in suprapubic pain and dysuria.

Dr. Lombardo is a senior resident in emergency medicine, and Dr. Supino is the associate program director of the emergency medicine residency at Jackson Health System/University of Miami.

Wednesday, February 20, 2019


The patient was blue, her primary care physician noted. Quite literally, in fact.

The 38-year-old woman had sought care for a recurrent urinary tract infection, and that's when her primary care physician found her pulse oximetry to be 74%. He was concerned about hypoxia and asked us to evaluate her.

The patient reported taking an SSRI for anxiety and having a hormone-eluting IUD. She had previously had a Roux-en-Y gastric bypass. She said she had a headache, but had been instructed not to take NSAIDs. She said she had just finished a course of Cipro for her UTI, but continued to be symptomatic with urinary frequency, urgency, and burning, for which she had been taking the over-the-counter drug phenazopyridine (Azo, Pyridium). Her exam was otherwise unremarkable, with no fever, chest pain, or shortness of breath.

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Her vital signs were a pulse of 104 bpm, respirations of 24 bpm, blood pressure of 138/74 mm Hg, and SpO2 of 92% on 4 lpm via nasal cannula (low 80s on arrival). The patient was cyanotic, and her lips and fingers were blue, but she was not dyspneic in conversation and walked to the bathroom without difficulty. She was mildly tachypneic and tachycardic, but her lung sounds were clear and she had no cardiac murmurs or thrills, abdominal abnormalities, or peripheral edema.

Her white blood cell count, hemoglobin, hematocrit, and D-dimer were within normal limits, and her arterial blood gas was unremarkable, not acidotic, and she had no oxygen, carbon dioxide, or bicarb abnormalities. A chest x-ray showed no infiltrate or effusion, and urine microscopy revealed 6-20 WBC and 6-20 RBC.

Atypical pneumonia, carbon monoxide poisoning, pulmonary embolus, left-right shunt, sarcoidosis were high on our initial differential list, but initial labs and studies did not support these. Instead we considered the five causes of hypoxemia. These can be broken down into two groups: those with a normal A-a gradient, which is the difference between inspired oxygen at the alveolar level (A) and that at the arterial level (a), and those caused by a high A-a gradient (less oxygen transferred from the alveoli to the blood).

High A-a Gradient Possible Causes

Ventilation/perfusion (V/Q) mismatch: This is most common of the five causes of hypoxemia. COPD is unlikely in a young nonsmoker, and she has no clinical indicators for asthma. Nevertheless, we gave an albuterol/ipratropium nebulizer, but she did not improve clinically. Questioning the negative D-dimer, a CTA of the chest was obtained to rule out pulmonary embolus, which revealed healthy lungs and no clot. Carboxyhemoglobin levels were negative, ruling out carbon monoxide poisoning.

Thickened diffusion barrier: Interstitial lung disease is the major culprit for this cause, a physical barrier to exchange. Examples are fibrotic changes like those in asbestosis and sarcoidosis. No fibrosis was seen on chest x-ray or CT, and no hilar adenopathy suggested of sarcoid disease. (Am Fam Physician. 1998;58[9]:2041; The patient had no history of pulmonary vascular or alveolar disease.

Right-left shunt: This most commonly is the result of atrial septal defect or ventricular septal defect. No murmur or thrill was appreciated on our patient's exam; an echocardiogram was obtained and was unremarkable. An alveolar shunt caused by a blockage, such as empyema or pulmonary edema, was unlikely given the woman's presentation, history, and exam. An AV malformation was not appreciated in the great vessels on CTA of the chest.

Normal A-a Gradient Possible Causes

Hypoventilation: The ABG showed normal PaO2 but not a high PaCO2, so this was ruled out. Clinically, the patient was not hypoventilating, was not taking opioids or any drugs that would suppress her respiratory drive, and did not have a chest wall disorder or obstructive disease such as COPD, obesity, or scoliosis/kyphosis.

Low inspired oxygen level: This would likely be seen at high altitude, and it was easily ruled out because we were at sea level.

Healing Thyself

The patient was interviewed and assessed a second time after being in the ED for several hours without a definitive diagnosis. She said she had 16 UTIs in the past year and that she takes Azo “all the time” because it was the only medication that relieves her symptoms and allows her to work.

She said she took four to six 97.2 mg tablets of phenazopyridine up to six times daily, and had been taking it for three to four days. This is about five times the maximum recommended dose (200 mg three times a day for a maximum of two days). (WebMD;

Phenazopyridine is a drug noted for causing acquired methemoglobinemia, which causes hypoxia via a V/Q mismatch by modifying the hemoglobin molecule. (Goldfrank's Toxicologic Emergencies, 9th ed. New York: McGraw-Hill Companies; July 1, 2010; p. 1698.) A methemoglobin level was obtained six hours after arrival, which was 15% and put her in the symptomatic but not emergent category for this condition. Normal levels are 0.5-3%. Emergent cases (40% methemoglobin level or hypoxic and not responding to conservative treatment) are treated with methylene blue. (UpToDate Sept 30, 2016;

The modification made by Azo to the Hg, changing some heme binding sites from ferrous (Fe++) heme to ferric (Fe+++) heme, prevented red blood cells from bringing oxygen to its end tissue, leading to tissue hypoxia. In some ways, this mimics carbon monoxide poisoning, but the difference is that the hemoglobin molecule is altered in methemoglobinemia, rendering it unable to transport oxygen, while the hemoglobin is unchanged but has an affinity to CO in CO poisoning, displacing oxygen. (UpToDate Sept 30, 2016; In both scenarios, the oxygen binds to the remaining Hg sites more tightly and is less likely to release at the tissue site, exacerbating the hypoxia. Other drugs that can do this are benzocaine, prilocaine, nitrates, metoclopramide (Reglan), and buprenorphine/naloxone (Suboxone). (British Colombia Drug and Poison Information Center, 2011;

The patient was admitted and observed overnight, and her condition had resolved at discharge with conservative management. She did not require methylene blue, only supplemental oxygen. She was counseled to avoid this medication in the future, and outpatient follow-up was arranged with urology for suspected interstitial cystitis.

Mr. Murphy is a board-certified emergency medicine physician assistant at MDI Hospital in Bar Harbor, ME.

Tuesday, February 12, 2019


A 30-year-old man with no previous medical history presented with one day of epigastric pain, nausea, and vomiting. He described the pain as moderate, aching, and nonradiating. He said Tylenol provided minimal relief.

The patient reported vomiting four or five times since the start of his symptoms and described the vomit as yellow in color. He had no history of recent travel, recent sick contacts, trauma, pain with eating, fever, chills, shortness of breath, chest pain, headaches, dizziness, changes in bowel movements, or urination. The patient confirmed a past surgical history for a broken left arm as a child. His father also had diabetes, and his paternal uncle had an unknown cancer.

The patient said he smokes cigarettes once a month, but reported no illicit drug use. He said he drinks beer, up to eight to 10, and confirmed drinking 10 beers two days before he presented to the ED. Review of systems confirmed abdominal pain, nausea, and vomiting, but all others were negative. His physical exam was unremarkable.

A CT with contrast of his abdomen and pelvis showed an ill-defined region of hyperenhancement at the hepatic dome but no cholelithiasis. Extensive peripancreatic stranding with enlargement and hypoenhancement were seen in the pancreatic head. Associated wall thickening with extensive stranding surrounding the distal gastric body and duodenum was also noted. Free fluid was seen in the right upper quadrant and along the right paracolic gutter, as was wall thickening with pericolonic stranding involving the distal ascending colon at the hepatic flexure and transverse colon, which was likely reactive to the peripancreatic and duodenal inflammatory change.

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A focal fitting defect at the portosplenic confluence was compatible with thrombus. An additional thrombus was found in the right portal vein. The patient was diagnosed with acute pancreatitis.

Patients with acute pancreatitis present clinically with an acute onset of pain. This pain is often located in the epigastric region, but can also be in the right upper quadrant or, in some cases, isolated to the left side. A small percentage of patients can have no pain, and may actually present with idiopathic hypotension. Ninety percent of patients with acute pancreatitis will present with nausea and vomiting. (UpToDate 2018;

The vast majority of patients will have tenderness to palpation in the epigastric region or diffuse abdominal tenderness to palpation. Other findings on physical exam may include abdominal distention, hypoactive bowel sounds, tachypnea, hypoxemia, hypotension, Cullen's sign, Grey Turner's sign, subcutaneous nodular fat necrosis, panniculitis, and hepatomegaly. Diagnosing acute pancreatitis requires the presence of two of three criteria: acute onset of persistent, severe epigastric pain often radiating to the back; elevation in serum lipase or amylase to three times or greater than the upper limit of normal (our patient's lipase was 920 U/L); and characteristic findings of acute pancreatitis on imaging (contrast-enhanced CT, MRI, or transabdominal ultrasound). Acute pancreatitis is typically self-resolving within five to seven days; patients should be NPO.

Acute pancreatitis can also cause portal vein thrombosis. Clinically, it may present as pain, but is clinically silent in many cases and is often incidentally diagnosed. (UpToDate 2018; Physical exam may demonstrate abdominal distension if the patient with portal vein thrombosis has an ileus. Laboratory studies are not the best diagnostic tool for this. They may show elevated acute phase reactants or in the case of patients with bowel infarction, metabolic acidosis, leukocytosis, and elevated hematocrit. The diagnosis is definitively made with abdominal imaging studies that show the portal vein occlusion—abdominal CT, MRI, or ultrasound. Treatment is anticoagulation. It is also important to investigate the underlying cause and treat it accordingly.

Ms. DePrimo is a fourth-year medical student at the University of Medicine and Health Sciences in St. Kitts, and Dr. Malik is the chief of emergency medicine at Weiss Memorial Hospital in Chicago.

Tuesday, February 12, 2019


An 81-year-old woman with a past medical history of atrial fibrillation, three coronary artery bypass graft surgeries, and a prior cerebrovascular accident presented to the emergency department with right arm pain. Her symptoms had grown worse for two days, and she experienced paralysis about two hours before arrival.

Her initial vital signs were a temperature of 97.7°F, a blood pressure of 196/43 mm Hg (left arm), a heart rate of 60 bpm, and a respiratory rate of 18 bpm. She had obvious pallor to her right upper arm with no brachial or radial pulses. She was unable to extend her fingers with 0/5 grip strength. Sensation was reduced below the elbow, with a capillary refill time of more than five seconds.

The remaining neurovascular and neurological exam was unremarkable. Cardiopulmonary exam revealed an irregularly irregular rhythm and lungs that were clear to auscultation bilaterally. She underwent an emergent CT angiogram of the right upper extremity that revealed luminal narrowing (Photo A) followed by eventual complete thrombotic occlusion of the right axillary artery (Photo B) with no evidence of blood flow distally.

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Acute limb ischemia like this patient's must be recognized quickly to avoid the complications that arise from untreated limb hypoperfusion. The signs and symptoms of acute limb ischemia include pain, pallor, parasthesias (late finding), poikilothermia, pulselessness, and paralysis (late finding). Research has shown that extensive tissue necrosis can occur within six hours. Emergent recognition with appropriate intervention is important for limb salvage.

The three main causes of thromboembolism are damage to the intima of the artery (penetrating or blunt trauma, thoracic outlet syndrome, vasculitis, fibromuscular dysplasia, atherosclerosis, and connective tissue diseases); hypercoagulable states (antiphospholipid syndrome, heparin-induced thrombocytopenia, hyperviscosity states such as sickle cell disease and leukostasis in leukemia, thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome); and hemodynamic blood flow disturbances such as embolic occlusion secondary to atrial fibrillation.

Our patient was taken emergently to the OR where she underwent embolectomy of the right axillobrachial artery and three-compartment right forearm fasciotomy. She was eventually transitioned from a heparin drip to apixaban. Arterial thrombosis was thought to be likely secondary to thromboembolic phenomenon from her atrial fibrillation. She improved during her hospital course, and was eventually admitted into inpatient rehabilitation. Her follow-up with vascular surgery a month later revealed that she had regained complete function of her right arm without pain.

Dr. Taylor is an emergency medicine resident at Beaumont Hospital in Farmington Hills, MI, a teaching hospital of Michigan State University. Dr. Zelenka-Joshowitz is an emergency physician and core faculty for the emergency medicine residency at Beaumont Hospital, Farmington Hills, MI, and a clinical instructor at Michigan State University.