Answer: ABCDE


DISCUSSION:

In patients with symptomatic malignant pericardial effusions, management options may be designed to establish a diagnosis, relieve symptoms, or prevent recurrence.

Pericardiocentesis is very successful in removing fluid for diagnosis and alleviating symptoms; however recurrence rates are greater than 50%. This rate can be reduced to around 20% with instillation of sclerosing agents such as tetracycline or bleomycin.

Surgical techniques, including subxiphoid pericardiotomy and thoracotomy with pericardiectomy, offer the highest success rates (approximately 90%) but are more invasive and usually require general anesthesia.

Systemic antitumor therapy with chemotherapy or radiation therapy can be effective in controlling malignant effusions in cases of sensitive tumors such as lymphomas, leukemias, and breast cancer.

Option B

Initial treatment consists of stabilizing the patient and gastric decontamination. As ethylene glycol is rapidly absorbed, gastric decontamination needs to be performed soon after ingestion to be of benefit. Gastric lavage or nasogastric aspiration of gastric contents are the most common methods employed in ethylene glycol poisoning. Ipecac-induced vomiting or activated charcoal (charcoal does not adsorb glycols) are not recommended.

Aggressive intervention should be initiated at the time of diagnosis. Intervention should consist of intravenous infusion of sodium bicarbonate to enhance renal clearance of glycolate through ion trapping; intravenous infusions of ethanol or fomepizole to block the metabolism of ethylene glycol; and hemodialysis for the removal of ethylene glycol and glycolate. Regular monitoring of the osmolar gap (corrected for ethanol level if I.V. ethanol is being used during treatment) and the anion gap will help guide therapy during hemodialysis.

Answer: b

Although small cell and non-small cell lung cancers do differ by histology and clinical behavior, they probably have a common origin since c-myc or n-myc amplified small cell lung cancer lines will undergo transition to non-small cell phenotypes after insertion of an activated ras/gene. The overall incidence of lung cancers is 80% non-small cell and 20% small cell. Only the small cell carcinoma is predictably responsive to chemotherapy.

The staging system for small cell lung cancer is based on limited vs. extensive disease outside of a tolerable radiotherapy portal while the International Staging System uses TNM descriptors for 4 clinical stages. Unfortunately, only about 30% of patients with non-small cell lung cancer have potentially resectable tumors.

Answer: c, e

Survival after resection for non-small cell lung cancer is related to the stage of the disease with a strong adverse effect from nodal involvement. This is true even for large peripheral tumors that extend into the chest wall as in this case where a 40–50% survival would be expected in the absence of nodes (T3N0:Stage IIIa) but only a 15% survival with nodal involvement. Radiation therapy would be a postoperative consideration to reduce the incidence of local recurrence. En bloc operative resection of the involved lobe and mediastinal nodes for staging would offer the greatest likelihood of cure.

Answer: c

There are a number of controversial areas in the area of operative approaches to metastatic disease in the lung, but there is general agreement that any extrathoracic metastases preclude eligibility for pulmonary resection. Although tumor doubling time is a measure of its aggressiveness, it is too variable to have prognostic significance and is generally disregarded as a criterion for resection. Primary site recurrence must be treated before the metastatic focus to prevent further seeding. If effective systemic therapy is available as would be expected in breast and testicular cancer or osteogenic sarcoma, it is preferred over surgical resection. Similarly, pulmonary resection should not be undertaken unless the pulmonary reserve will allow all metastatic foci to be resected.

Answer: a, c, d

In the absence of atypia, carcinoids are only locally malignant and can be managed by limited lung and/or bronchial resection. Therefore, a sleeve resection of the bronchus preserving distal lung would be appropriate. Lymph node sampling at the time of resection, however, is advisable to ensure that a complete resection has been performed. The carcinoid syndrome is rarely found except in the presence of a large primary tumor or hepatic metastases. When the carcinoid syndrome does occur, it is left-sided cardiac valves that are affected rather than right, which one would expect with gastrointestinal carcinoids.

Answer: b, c, e

Preoperative cessation of smoking for a period of 2 weeks can reduce pulmonary complications and should be required. In the preoperative assessment for pulmonary resection, the PaCO2 is of more value than the PaO2 since an elevated PaCO2 > 50 mmHg identifies the very high risk patient with chronic lung disease. Hypoxemia may be secondary to the mechanical effects of the tumor producing ventilation/perfusion mismatch. The latter can be confirmed by V/Q lung scan which also serves to identify areas of functioning lung in patients with marginal pulmonary function. The best screening test for adequacy of pulmonary reserve is the FEV1. It identifies obstructive pulmonary disease which is more important than the restrictive lung disease identified by vital capacity measurement. Diffusion capacity measurement provides little additional information of value.

Option c

Rhabdomyolysis causes hyperkalemia.

Option B

Option B

Hemodialysis removes toxins, electrolytes, and fluid by circulating the patients’ blood through a hemodialyzer (artificial kidney). Patients are usually scheduled to receive hemodialysis for two to six hours three times per week. The basic components of hemodialysis include circulatory access, water treatment system, water distribution system, dialysate (components), dialysis machines, blood tubing and the hemodialyzer

Option D

Rhabdomyolysis is a potentially life-threatening syndrome resulting from the breakdown of skeletal muscle fibers with leakage of muscle contents into the circulation.

The most common causes are crush injury, overexertion, alcohol abuse and certain medicines and toxic substances.

Several inherited genetic disorders, such as McArdle's disease and Duchenne's muscular dystrophy, are predisposing factors for the syndrome.

Clinical features are often nonspecific, and tea-colored urine is usually the first clue to the presence of rhabdomyolysis.

Hepatic dysfunction occurs in only about 25 percent of the individuals.

Option D

Alcoholism is another common cause of rhabdomyolysis. This may be secondary to to alcohol related trauma, seizures, or coma, or may be due to a direct toxic effect of ethanol on skeletal muscle, resulting in both a chronic myopathy, and acute rhabdomyolysis

Alcohol directly injures the sarcolemma and increases sodium permeability. This in turn increases the activity of the Na+,K+-ATPase pump, with the eventual exhaustion of energy stores. Increased cytosolic Na+ enhances the accumulation of cytosolic Ca++, which in addition to increased mitochondrial Ca++ causes cellular injury. Analysis of skeletal muscle from chronic alcoholics and experimental animals fed ethanol shows a marked depletion of potassium, phosphorus, and magnesium, and elevated sodium, chloride, calcium and water content. Acute hypophosphatemia would shut off ATP synthesis.

Uniform muscle necrosis, leukocyte and macrophage invasion of degenerated muscle fibers are observed with light microscopy, and ultrastructural changes include the separation of myofibrils and other cellular elements by clear spaces.

Acute alcohol-induced rhabdomyolysis can occur after binge drinking or a sustained period of alcohol abuse, and is associated with pain and swelling of muscles, particularly the quadriceps.

Symptoms resolve if the patient abstains from alcohol use.

Option B

Disseminated intravascular coagulation may develop in patients with rhabdomyolysis. This complication is usually worse on the third to fifth day of presentation.

Compartment syndrome may be an early or late complication, resulting mainly from direct muscle injury or vigorous muscle activity. This complication occurs primarily in muscles whose expansion is limited by tight fascia, such as the anterior tibial muscles. Peripheral pulses may still be palpable, in which case nerve deficits (mainly sensory) are more important findings. A delay of more than six hours in diagnosing this complication can lead to irreversible muscle damage or death. Decompressive fasciotomy should be considered if the compartment pressure is greater than 30 mm Hg.

Option C

Screening may be performed with a urine dipstick test. The orthotoluidine portion of the dipstick turns blue in the presence of hemoglobin or myoglobin. Positive urine "blood" can be used as a surrogate marker for myoglobin if freshly spun sediment of urine shows no red blood cells. In this setting, a serum sample with normal color indicates myoglobinuria, whereas a pigmented brown or red serum sample indicates hemoglobinuria.

Option B

Initial hypocalcemia should not be corrected unless a patient is symptomatic. It is important to avoid further aggravating the hypercalcemia that commonly develops during the recovery phase of rhabdomyolysis, when calcium deposited in the injured muscles is mobilized back to the extracellular space.

Option C

Option B

Traumatic, Heat-Related, Ischemic and Exertional Causes of Rhabdomyolysis

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Traumatic causes

Lightning strike

Immobilization

Extensive third-degree burn

Crush injury

Heat-related causes

Heatstroke

Malignant hyperthermia

Neuroleptic malignant syndrome

Ischemic causes

Ischemic limb injury

Exertional causes

Marathon running

Physical overexertion in untrained athletes

Pathologic muscle exertion

Heat dissipation impairment

Physical overexertion in persons with sickle cell disease

Infectious, Inflammatory, Metabolic and Endocrinologic Causes of Rhabdomyolysis

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Infectious causes

Viruses: influenza virus B, parainfluenza virus, adenovirus, coxsackievirus, echovirus, herpes simplex virus, cytomegalovirus, Epstein-Barr virus, human immunodeficiency virus

Bacteria: Streptococcus, Salmonella, Legionella, Staphyloccus and Listeria species

Inflammatory causes

Polymyositis

Dermatomyositis

Capillary leak syndrome

Snake bites (mostly in South America, Asia and Africa)

Metabolic and endocrinologic causes

Electrolyte imbalances: hyponatremia, hypernatremia, hypokalemia, hypophosphatemia, hypocalcemia

Hypothyroidism

Thyrotoxicosis

Diabetic ketoacidosis

Nonketotic hyperosmolar syndrome

Option B

The treatment of rhabdomyolysis is primarily directed at preserving renal function. Up to 12 L of fluid may be sequestered in the necrotic muscle tissues, thereby contributing to hypovolemia, which is one cause of renal failure in patients with rhabdomyolysis.

Initially, normal saline should be given at a rate of 1.5 L per hour. Urine output should be maintained at 300 mL per hour until myoglobinuria has ceased. High rates of IV fluid administration should be used at least until the CK level decreases to or below 1,000 units per L. If these measures successfully thwart the development of oliguria, the patient can be switched to 0.45 percent saline with the addition of one or two ampules of sodium bicarbonate (40 mEq) and 10 g per L of mannitol.

The objectives are to alkalinize urine to a pH of greater than 6.5 (thereby decreasing the toxicity of myoglobin to the tubules) and to enhance the flushing of myoglobin casts from renal tubules by means of osmotic diuresis.

Option D

Acute renal failure and diffuse intravascular coagulation are late complications of rhabdomyolysis (i.e., past 12 to 24 hours). Acute renal failure, the more serious complication, develops in up to 15 percent of patients and is associated with high morbidity and mortality.

Renal damage results from the mechanical obstruction of tubules by myoglobin precipitation, the direct toxic effect of free chelatable iron on tubules, and hypovolemia.

In addition, the release of vasoactive kinins from muscle may interfere with renal hemodynamics. There is a loose predictive correlation between CK levels and the development of acute renal failure, with levels higher than 16,000 units per L more likely to be associated with renal failure.

The rate at which serum creatinine levels increase is typically faster in patients with myoglobinuric renal failure (up to 2.5 mg per dL per day [220 µmol per L]) than in those with other causes of acute renal failure.

Option C

Complications of Rhabdomyolysis

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Early complications

Hyperkalemia

Hypocalcemia

Hepatic inflammation

Cardiac arrhythmia

Cardiac arrest

Late complications

Acute renal failure

Disseminated intravascular coagulation

Early or late complication

Compartment syndrome

Answer: a, b, d

The risk of local recurrence for non-small cell carcinomas of the lung is much more common for those of squamous cell histology than the others and averages 20%–30% overall. The greatest risk, however is of distant metastases which occur in 70%–80% of patients, regardless of stage. Almost all recurrences are seen within five years, and of the distant metastatic sites, the brain is most commonly affected. In this patient with Stage II disease, radiation therapy would be a consideration to reduce the incidence of local recurrence, but not chemotherapy. After five years, the highest risk would be from a new lung cancer rather than a recurrence.

Answer: b, d

In the evaluation of a solitary lung lesion, previous radiographs are important, particularly if the lesion is new. A coin lesion that is growing slowly does not necessarily indicate malignancy, since the most common benign tumor, hamartoma, has a variable pattern of slow growth and typically will show “popcorn” calcification. Concentric calcification is also most suggestive of a benign granuloma. In the absence of previous radiographs, the lesion must be assumed to be malignant until proved otherwise and should not be dismissed to follow-up. If a CT scan shows mediastinal adenopathy, then mediastinoscopy with biopsy is appropriate to make a diagnosis. Needle aspiration results of “chronic inflammatory cells” is non-diagnostic.

Answer: all of the above

The term bronchial adenoma includes a spectrum of tumors arising from epithelial stem cells which vary from the benign mucous gland adenoma to the malignant adenoid cystic and mucoepidermoid carcinomas as well as the carcinoid tumors of similar varied behavior. Among these variants, the carcinoid are most common representing 80%–90% of all bronchial adenomas.

Answer: d, e

The presence of a pleural effusion in association with a primary lung cancer is usually an ominous sign precluding surgical resection. However, if more than one sample of the effusion is negative for malignant cells and it is non-bloody, it can be considered unrelated to the tumor and excluded as a staging element. When the effusion cytology is positive, the tumor is considered T4 regardless of size or nodal status.

Answer: c

Chest wall tumors are uncommon, accounting for only 1–2% of all body tumors. About 57% of chest wall tumors are primary, whereas 43% are metastatic. Solitary metastases most frequently arise from the thyroid gland, the GU tract and the colon. Overall, about 60% of chest wall tumors are malignant, most arising form bone or cartilage. The CT scan is of value in demonstrating the relationship between the mass and contiguous structures, but of little value in determining bone destruction because of the oblique course of the ribs. Specific rib films are most helpful. Now that multimodality therapy is available, core needle biopsies are recommended and have not increased the incidence of local recurrence.

Answer: a, b

A new pulmonary lesion in a patient with a history of a previously treated malignancy poses a diagnostic and therapeutic challenge. A CT scan should always be obtained since plain radiographs can detect lesions only 9 mm in diameter or greater. The lesion is most likely to be metastatic if the prior malignancy was sarcoma or melanoma and most likely to be a new primary lung cancer if the prior malignancy originated in the head, neck or breast. When the original lesion was in the GI or GU tract, there is an equal chance that it is metastatic or a new primary. Fine needle aspiration does not usually alter the plan for excision and is done only when the patient is not an operative candidate or desires to know the diagnosis.

Answer: b, c

The complication of tracheoinnominate artery fistula characteristically occurs in young women and is often heralded by bleeding during the tracheostomy suctioning. Deflation of the tracheal tube cuff confirms the diagnosis if massive bleeding occurs. At that point the tracheal tube cuff should be overinflated and a finger inserted into the tracheostomy incision to tamponade the bleeding. Throughout this, the airway must be protected. Operative repair through an upper sternal split requires resection of the innominate and coverage of the oversewn vessels with viable tissue since the wound is contaminated. No prosthetic material should be inserted and tracheal resection is not necessary.