Internal Medicine
Board Review

Educational Objective:

Diagnose local reactions to insect stings and differentiate from anaphylaxis.

Key Point:

Local pruritic reactions to stings are not associated with stridor, dyspnea or hypotension and can be managed symptomatically with antihistamines and other therapies, rather than epinephrine.

Explanation:

The most likely etiology of this patient’s rash is a local reaction to an insect sting. Most insect stings are from members of the Hymenoptera order that includes honey bees, bumble bees, yellow jackets, yellow hornets, white-faced hornets, paper wasps, fire ants, harvester ants, bulldog ants, and jack-jumper ants.

This patient lacks any signs of anaphylaxis. Given her history of a pruritic rash, history of being outdoors when the rash appeared, it is likely that this represents a local reaction to an insect sting. Although cellulitis is a possibility, it is not typically associated with pruritus, nor is necrotizing fasciitis.

Management includes limb elevation, cold compresses, topical steroids, and oral nonsedating antihistamines. Systemic steroids can be provided for a few days if a large amount of swelling Remains

References:

Freeman T. Bee, yellow jacket, wasp, and other Hymenoptera stings: Reaction types and acute management. Revised September 10, 2015. Accessed February 5, 2016.

Tran PT, et al. Allergy, hypersensitivity, angioedema, and anaphylaxis. In: Marx JA, et al. Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed.,2014.1543-1557.e.2.

Educational Objective:

Recognize the risk factors for tuberculosis in the United States.

Key Point:

HIV infection is the most important contributor to the re-emergence of TB in the United States.

Explanation:

In the United States, the HIV/AIDS epidemic has had the largest impact on the re-emergence of TB. Immigration from endemic countries, residing in a skilled nursing facility, and homelessness in urban areas are also important risk factors for the disease. In 2013, 7% of patients with TB were coinfected with HIV, 6% were homeless, and 4% were incarcerated. The incidence of TB is 13 times higher in foreign-born individuals than in those born in the United States. The expanding elderly population is not a risk factor for TB. Economic hardship, homelessness and immigration have contributed to the reemergence of TB in the United States, but their contribution has been modest in comparison with that of HIV/AIDS.

Reference:

Ellner JJ. Tuberculosis (chapter 324). In: Goldman L, Schafer A. Goldman-Cecil Medicine. 25th ed., 2016:2030-2039.

Educational Objective:

Identify perirectal/perianal abscesses.

Key Point:

Irritation of the perianal area may be associated with perirectal abscess. Nearly one-half of the abscesses in this area are complicated with the forming of a fistula, which can be treated with an elliptical incision.

Explanation:

Most patients with perirectal abscesses have a continued dull and aching pain brought on by the space-occupying nature of the abscess. Pain can be sharp with defecation, but that is more commonly a characteristic of an anal fissure. Offloading the pressure on the affected area by lying prone or sometimes standing can help the pain as well. Abscesses can "ripen" into fluctuance, but not all do.

Almost one-half of perirectal abscesses are complicated by fistula formation, and the rate of fistula formation is not necessarily decreased by incision and drainage. Treatment is generally an elliptical incision.

Reference:

Steele SR, Kumar R, Feingold DL, Rafferty JL, Buie WD; Standards Practice Task Force of the American Society of Colon and Rectal Surgeons. Practice parameters for the management of perianal abscess and fistula-in-ano. Dis Colon Rectum. 2011;54:1465-1574.

Educational Objective:

Identify xanthoma as a manifestation of hyperlipidemia.

Key Point:

Xanthomas are deposits of lipids in the skin. In the vast majority of cases, xanthomas are a manifestation of hyperlipidemia. Several different types of xanthomas exist, including an eruptive form associated with hypertriglyceridemia.

Explanation:

The next best step in this scenario would be to check her lipid profile. The patient has eruptive xanthomas, which usually present as a group of papular lesions yellow in color, possibly with an erythematous appearance, and can occur suddenly, especially in areas prone to trauma. Eruptive xanthomas are suggestive of hypertriglyceridemia, generally when levels are above 1,000 mg/dL. When the size of the papular lesions is larger, the type of xanthomas is classified as being tuberous.

In the vast majority of cases, xanthomas are manifestations of hyperlipidemia. Tendinous xanthomas may occur as nodules over muscle tendons. Xanthelasmas are yellowish deposits in the eyebrows. Tendinous xanthomas and xanthelasmas are more frequently associated with elevated cholesterol levels, not hypertriglyceridemia.

The patient does not have any symptoms suggestive of a rheumatologic condition, so testing for rheumatoid arthritis, lupus erythematosus, or vasculitides is not appropriate.

ESR and CRP levels are unspecific, acute-phase reactants, so abnormal values will not have diagnostic value on this patient.

Any patient with a type of xanthoma should be evaluated for familial hyperlipidemia syndrome.

Reference:

Baron RB. Lipid disorders. In: Papadakis MA, et al, eds. Current Medical Diagnosis & Treatment. 2016:1202-1211.

Educational Objective:

Know the critical complications of hemorrhagic shock that must be addressed if the patient is to survive.

Key Point:

The combination of acidosis, hypothermia and coagulopathy is usually lethal unless these factors are promptly corrected.

Explanation:

The triad is made up of acidosis, hypothermia, and coagulopathy. Although the other factors listed are never desirable, the combination of these 3 is particularly deadly. In hemorrhagic shock, monitoring clotting factors, acidosis, and temperature are priorities. The pathophysiologic explanation for this triad is multifactorial. Inadequate tissue perfusion results in increased lactate production leading to metabolic acidosis.

Shock results in diminished adenosine triphosphate (ATP) production, which is thought to be due to inadequate delivery of nutrients to the cells. ATP, in turn, helps to maintain homeostatic temperatures. Diminished ATP production results in the body drifting to the ambient temperature.

Deficiency of clotting factors result from a combination of consumption during massive hemorrhage, dilution from infusion of fluid devoid of clotting factors, and reduction in clotting factor activity as the result of hypothermia (proposed).

References:

Hanke AA, Rahe-Meyer N. Trauma-induced coagulopathy. Unfallchirurg. 2014;117:95-98.

Rhee P. Shock, electrolytes and fluid. In: Townsend CM Jr, et al. Sabiston Textbook of Surgery: The Biological Basis of Modern Surgical Practice. 19th ed., 2012.