Trunk



Trunk





OVERVIEW

The trunk is a large area that is host to a vast assortment of inflammatory, autoimmune, idiopathic, and neoplastic skin disorders. There are also many eruptions and symptoms that result from adverse drug reactions, infestations, as well as viral and bacterial infections.

Since the trunk is generally sun-protected by clothing, it is less likely to develop nonmelanoma skin cancers such as actinic keratoses, basal cell carcinomas, and squamous cell carcinomas; however, the back and anterior torso are common sites for melanoma to appear, particularly in men. (Since most of the infectious eruptions of the trunk occur in infants and children, Fever and Rash discusses them in Chapter 21.)



CHEST AND BACK


Pruritus



Pruritus, the most common symptom of all skin diseases, can be simply defined as an unpleasant sensation that elicits the urge to scratch. It is most commonly associated with a primary skin disorder such as xerosis, atopic dermatitis, urticaria, lichen planus, psoriasis, arthropod assault reaction, or it may be idiopathic. Pruritus is more common in the elderly.

Pruritus may present as a primary complaint, as an indication of an underlying systemic or psychiatric disorder, or as an isolated problem with no other explanation (pruritus of unknown origin). There are numerous exogenous causes such as drugs, cocaine abuse, contact dermatitis (e.g., poison ivy), scabies, lice infestation, fiberglass, and aquagenic pruritus.

Patients who suffer from chronic, unremitting, itching without signs of a primary skin condition, or an obvious exogenous or psychogenic cause, should undergo a thorough evaluation for an underlying systemic disorder such as chronic renal failure, acquired immunodeficiency syndrome, polycythemia vera, cholestasis, primary biliary cirrhosis, diabetes mellitus, thyroid disease, carcinoid syndrome, as well as an associated malignancy, such as Hodgkin disease, leukemia, and multiple myeloma.



Diagnosis

A search for the cause of the pruritus is based on the following:



  • A careful history


  • Physical findings (e.g., linear excoriations and crusts) (Fig. 11-1)


  • Appropriate symptom directed lab tests








Management



  • Relies on establishing the cause and then either treating or removing it


  • Specific therapy for any underlying skin or internal disease


Topical Treatment May Include



  • Ice packs to cool the skin


  • Menthol/camphor lotions


  • Regular use of emollients, especially if skin is dry


  • Topical corticosteroids for short periods


  • Topical calcineurin inhibitors such as tacrolimus 0.1% ointment (Protopic) or pimecrolimus 1% cream (Elidel) for itch associated with inflammatory skin conditions


  • Topical dapsone 5% cream (Zonalon)


  • Crisaborole 2% ointment (Eucrisa)


  • Topical hypochlorous acid-based topical prescription products (Levicyn™ Antipruitic Gel, or Dermal Spray)


Systemic Treatment May Include



  • Antihistamines—most useful in urticaria in which histamine is released but are not very effective for pruritus. However, sedating antihistamines can be used primarily for their sedative effects


  • Doxepin and amitriptyline—tricyclic antidepressants that have antipruritic action


  • Antiepileptic drugs—sodium valproate, gabapentin, and pregabalin


  • Dupixent, a monoclonal antibody that binds to the alpha subunit of the interleukin-4 receptor (IL-4Rα) and modulates both IL-4 and IL-13 signaling, appears to be highly effective for pruritus, though it is not yet officially approved for this indication


Phototherapy



  • Broadband ultraviolet B or narrow-band UVB phototherapy alone, or in conjunction with UVA, has been shown to be helpful for pruritus associated with chronic kidney disease, psoriasis, atopic eczema, and cutaneous T-cell lymphoma


helpful hintsHelpful Hints



  • Scabies should be considered if more than one family member itches


  • Hodgkin disease may present with pruritus of unknown origin that precedes the diagnosis by up to 5 years


  • Topical antihistamines should not be used for chronic itch because they may sensitize the skin and result in allergic contact dermatitis



Notalgia Paresthetica



Notalgia paresthetica (NP) most often presents with a localized, unilateral area of recurrent itching, less often pain, that characteristically occurs on the lower or mid-scapula. NP is a common condition seen most often in middle-aged and elderly patients. It is thought to represent a sensory neuropathy that may be caused by nerve impingement from spinal arthritis.



Diagnosis



  • Intermittent itching in a specific place; typically, on the lower or mid-scapula


  • The localization and postinflammatory hyperpigmentation that sometimes results from the chronic rubbing and scratching reveals the diagnosis and is often the only clinical finding (Fig. 11-2)



Management



  • Topical corticosteroids, topical anesthetics (e.g., pramoxine or lidocaine), and oral gabapentin as well as acupuncture bring variable results


  • Capsaicin cream (Zostrix), which depletes nerve endings of their chemical transmitters, applied three to five times daily may decrease symptoms


  • There have been case reports of successful treatment with botulinum toxin type A for this condition; however, treatment is often futile







Nodulocystic Acne



Nodulocystic acne (NA) is a severe form of acne affecting the face, chest, and back. It is characterized by multiple inflamed nodules that frequently result in scars, both hypertrophic and atrophic. The nodules favor the chest, shoulders, the back, the face, the buttocks, and upper arms. Acne conglobata (AC) is an uncommon and unusually severe form of NA. Conglobate means a gathering into balls (Latin globus, ball). AC is characterized by burrowing and interconnecting abscesses and scars, often producing pronounced disfigurement. Both NA and AC are seen most often in males.


Distinguishing Features



  • Nodules, cystic lesions, pustules (Fig. 11-3)


  • Healing with hypertrophic as well as atrophic scars


  • Abscesses and interconnecting sinuses may result



Management



  • See Cheeks


  • Treatment may require a combination of medications that includes oral antibiotics, intralesional steroid injections, and possibly hormonal therapy in women


  • If all else fails, the recommended treatment for nodulocystic acne is oral isotretinoin (formerly known as Accutane), which, if started early, may prevent scarring. The treatment is required for at least 5 months, and repeated courses are sometimes necessary








Hypertrophic Scar



A hypertrophic scar represents an exaggerated formation of scar tissue in response to skin injuries such as lacerations, infections, insect bites, and surgical wounds. These scars are widened, thick, and unsightly lesions that do not extend beyond the original boundaries of an original injury.

Hypertrophic scars also may result from healed inflammatory lesions (e.g., acne, chickenpox). Such exaggerated scars occur less frequently at the extremes of age—the very young and the elderly. There is no racial preponderance as seen in keloids. In recent years, the popularity of skin-piercing procedures and tattooing has increased the frequency of these undesirable scars and has expanded the sites on the body where they may occur.


Distinguishing Features



  • Elevated, firm, shiny, hairless, papules, or nodules; may be flesh-colored or tan


  • Lesions that are inflamed are usually of recent onset. They may be red or purple in color (Fig. 11-4)


  • Most often, they arise on the sternum (Fig. 11-5), the deltoid region of the upper arm, shoulders, and upper back


  • The most common sites on the head and neck are the earlobes, nasal alae, mandibular border, and posterior neck


  • Unlike keloids, the hypertrophic scar reaches a certain size and subsequently stabilizes or regresse, whereas keloids do not regress without treatment and tend to recur after excision













Diagnosis



  • Clinical appearance



Management



  • Advise patient to discontinue or avoid repetitive skin trauma such as tattooing and skin-piercing practices, particularly in areas that are prone to abnormal scarring such as the presternal areas and earlobes


  • Topical corticosteroids: clear surgical tape impregnated with flurandrenolide (Cordran Tape) has been shown to soften and flatten hypertrophic scars over time


  • Intralesional corticosteroid injections (triamcinolone 10 to 40 mg/mL); these injections are also useful for diminishing pruritus and tenderness


  • Pulsed-dye lasers and resurfacing lasers such as CO2 laser and Erb:Yag and nonablative fractional lasers have been used successfully on some persistent hypertrophic scars


Keloid



A keloid is an overgrowth of dense fibrous tissue, a scar whose size far exceeds that which would be expected from the extent and margins of an injury to the skin (see also Ears). As with hypertrophic scars, keloids are an exaggerated response to a skin injury, inflammatory lesion (e.g., acne), or a surgical wound.



Distinguishing Features



  • Uncontrolled overgrowth of scar tissue with extension beyond the site of the original wound with a tendency to send out “claw-like” prolongations (Fig. 11-6)


  • Usually asymptomatic, although some are pruritic and others may be quite painful and tender


  • Keloids, by virtue of their excessive size, are generally of great cosmetic concern to patients



Diagnosis



  • Clinical appearance



Management



  • Intralesional corticosteroid injections with triamcinolone acetate, often in concentrations as high as 40 mg/mL per treatment, can help flatten keloids and diminish itching and erythema. A 27- to 30-gauge needle at 4- to 6-week intervals often helps to flatten the lesions (Fig. 11-7). Overtreatment may result in skin atrophy, telangiectasias, and overdepressed scars (Fig. 11-8)


  • Excision using aseptic operative technique in combination with other postoperative modalities, such as triamcinolone acetate injections, compression dressings, silicone sheeting, radiotherapy, topical imiquimod cream, or injected interferon


  • Lasers have been used as alternatives to excision. As with excisional therapy, laser results are best when combined with postoperative injected steroids


  • There is recent evidence that dupilumab (Dupixent), which is an effective treatment for atopic dermatitis, may be beneficial in managing keloids












Adverse Drug Reactions



The trunk is a common site for adverse drug reactions (ADRs) to appear. Undesirable reactions to drugs are more often seen in the elderly because seniors take more drugs than younger people, frequently taking more than one drug at a time, and are more likely to have been previously sensitized. Furthermore, individuals who are immunocompromised have a higher risk of developing a drug eruption than the general population.

Reactions to drugs may be allergic (immunologic) or nonallergic (toxic). Certain classes of systemic medications, such as antimicrobial agents, nonsteroidal anti-inflammatory drugs (NSAIDs), chemotherapeutic agents, and psychotropic agents, are particularly associated with a high rate of cutaneous reactions. Nonallergic drug eruptions are more common than allergic-type eruptions. Vertigo due to high-dose oral minocycline and irritant reactions from topical retinoids are examples of nonallergic reactions.

Most ADRs appear as macular and papular (morbilliform) rashes as noted in measles and they usually fade in a few days. More serious reactions include exfoliative erythroderma, erythema multiforme major (Stevens-Johnson syndrome), and toxic epidermal necrolysis (all are discussed in Generalized Eruptions). Other cutaneous reactions to drugs include erythema nodosum, urticaria, fixed drug eruption, vasculitis, purpura, and photosensitivity reactions (see Table 11-1).















Common Examples of ADRs

Morbilliform reactions (measles-like) consist of blanchable red macules and papules that are seen predominantly on the trunk, thighs, upper arms, and face. Most often caused by sulfonamides, penicillin, aspirin, blood products, hydantoins, thiazide diuretics, allopurinol, quinidine, ACE inhibitors, barbiturates, carbamazepine, isoniazid, NSAIDs, and phenothiazines.


Distinguishing Features



  • Reactions often occur suddenly with or without fever and are often indistinguishable from viral exanthems


  • Lesions are pink, red, or purple in color (Fig. 11-9)


  • May become confluent in a symmetric, generalized distribution that often spares the face


  • Itching is common. The mucous membranes, palms, and soles may be involved


  • The onset occurs 7 to 10 days after starting the responsible drug, but sometimes may not appear until after the drug is discontinued


  • An eruption may last for 1 to 2 weeks and then fade

Acneiform eruptions generally appear on the trunk and are usually due to systemic steroids, topical steroids, lithium, and androgenic hormones.


Distinguishing Features



  • Lesions generally appear on the trunk as monomorphic acne-like papules and pustules (Fig. 11-10)

Contact dermatitis may be an irritant reaction from a topical tretinoin for acne or an allergic contact dermatitis from, e.g., topical neomycin or a preservative in a topical medication.

Photosensitive and phototoxic reactions are most commonly induced by phenothiazines, thiazide diuretics such as hydrochlorothiazide, griseofulvin, and doxycycline.


















Distinguishing Features



  • Lesions appear in sun-exposed areas such as the “V” of the neck, upper sternum, extensor forearms, and the face as an exaggerated sunburn (Fig. 11-11)

Pruritus without a rash may be seen with ACE inhibitors.

Urticarial eruptions are most often caused by penicillin derivatives and sulfa drugs (see next section).


Diagnosis of Drug Eruptions



  • Obtaining a detailed, careful history is paramount


  • A drug-induced reaction should be considered in the differential diagnosis of any symmetric cutaneous eruption with sudden onset in a patient who takes medications


  • Skin biopsy of an exanthem showing perivascular lymphocytes and eosinophils may be helpful, but not diagnostic


  • Patch tests are useful in diagnosing allergic contact dermatitis (see Appendix: Diagnostic and Therapeutic Techniques)



Management



  • Often, the decision whether to continue or discontinue a potentially vital drug presents a dilemma


  • The presence of urticaria, mucosal involvement, extensive or palpable purpura, or blisters almost always requires discontinuation of the responsible drug


  • Oral antihistamines such as diphenhydramine (Benadryl), hydroxyzine (Atarax), or the nonsedating agents such as cetirizine (Zyrtec) or loratadine (Claritin) may be helpful


  • Systemic steroids are given only in severe cases in which an infectious etiology is ruled out


helpful hintsHelpful Hints



  • A drug eruption may easily be confused as being a feature of the condition that it is intended to treat (e.g., a viral exanthem treated with an antibiotic)


  • If it is necessary to continue a responsible drug (i.e., there is no alternative medication) and the adverse reaction is mild or tolerable, the difficulty can be minimized by decreasing the dosage or treating the adverse drug reaction


  • If a patient is taking multiple medications, it is sometimes difficult to identify the specific agent that is responsible for an adverse reaction. In these instances, a reference guide to drug eruptions and interactions could suggest the most likely suspect drug


  • An ADR can occur days after a drug has been discontinued


  • ADRs from systemic medications tend to be symmetrical in distribution; however, certain eruptions have specific regional predilections (e.g., fixed drug eruptions and erythema nodosum)



Urticaria



Urticaria, commonly known as “hives,” is a reaction of cutaneous blood vessels that produces a transient dermal edema consisting of papules or plaques of different shapes and sizes. Individual lesions of urticaria typically do not persist in the same location for more than 24 hours. Urticaria may be classified as acute or chronic. By definition, in acute urticaria hives last for less than 6 weeks; chronic urticaria lasts longer than 6 weeks.

Pathophysiology involves the release of histamine and other compounds by mast cells and basophils. Mast cell activation causes degranulation of intracellular vesicles that contain histamine, leukotriene C4, prostaglandin D2, and other chemotactic mediators that recruit eosinophils and neutrophils into the dermis. Histamine and chemokine release leads to extravasation of fluid into the dermis resulting in edema.

Histamine effects account for many of the clinical and histologic findings of urticaria. Immune-mediated urticaria is activated by immunoglobulin E (IgE). Certain foods, drugs, acute upper respiratory infections, parasites, and whole blood transfusions are the most common causes.

Non-IgE-mediated urticaria includes reactions to certain physical stimuli that can produce hives in susceptible individuals. Physically induced urticarias include dermatographism, cold urticaria, solar urticaria, aquagenic urticaria, and exercise-induced urticaria.


Acute Urticaria



Acute urticaria may be caused by an obvious precipitant such as an acute upper respiratory infection, a drug reaction, a parasitic infection, or bee sting. The most common drugs that may cause acute urticaria are antibiotics (especially penicillin and sulfonamides), as well as pain medications such as aspirin, NSAIDs, narcotics, radiocontrast dyes, diuretics, and opiates, e.g., codeine. The most common foods associated with acute urticaria are milk, wheat, eggs, chocolate, shellfish, nuts, fish, and strawberries. Food additives and preservatives such as salicylates and benzoates may also be responsible.


Distinguishing Features



  • Wheals are the color of the patient’s skin or appear pale red


  • Pruritus without excoriations


  • Annular or gyrate shapes (Fig. 11-12)


  • Individual lesions, by definition, last less than 24 hours (evanescent wheals)


  • Overall, acute urticarial episodes can last for days (generally less than 30 days)


  • Lesions may be accompanied by a deeper swelling (angioedema)








Diagnosis



  • The diagnosis is usually made on clinical observation and history



Management



  • If possible, the cause of the hives should be determined and eliminated


  • Treatment is symptomatic with antihistamines, cool soaks, and ice packs


  • Over-the-counter first-generation sedating antihistamines, such as histamine H1 blockers: hydroxyzine (Atarax), diphenhydramine (Benadryl), and cyproheptadine (Periactin)


  • Over-the-counter second- and third-generation less-sedating antihistamines: loratadine (Claritin), fexofenadine (Allegra), cetirizine (Zyrtec), and levocetirizine (Xyzal), may be used during the daytime


  • Antihistamines can be used at up to four times the standard dose in the treatment of urticaria


  • A more sedating H1/H2 blocker such as doxepin (Sinequan) can be prescribed at a much lower dosage than when it is used as an antidepressant, especially at bedtime

image Alert: Anaphylaxis or an anaphylactoid reaction can occur

image Alert: Epinephrine, which is sometimes administered by intramuscular or subcutaneous injection for acute urticaria, should not be used for routine cases of hives; rather, it should be reserved for cases of acute anaphylaxis

image Alert: Patients who have severe anaphylactic reactions should consider wearing a Medic Alert Bracelet that describes their problem



Chronic Urticaria



Chronic urticaria, often referred to as chronic idiopathic urticaria (CIU) when no underlying cause is identified, is defined as urticaria that lasts for more than 6 weeks. It is most commonly seen in middle-aged women. In some instances, an autoimmune disorder, such as hyper- or hypothyroidism, Celiac disease, or Sjogren syndrome, may be associated with chronic urticaria.


Distinguishing Features



  • The morphology and duration—less than 24 hours—of individual lesions is similar to that of acute urticaria; however, the condition, by definition, lasts for more than 6 weeks


  • Patients may also experience a coexistent physical urticaria such as dermatographism (see below)


  • Symptoms may continue for weeks, months, or years; however, in most cases the disease ends spontaneously



Diagnosis



  • The diagnosis is usually made on clinical observation and history


  • A symptom-directed search for an underlying illness (e.g., systemic lupus erythematosus, thyroid disease, and lymphoma) should be undertaken


  • If a complete review of systems is normal and a physical urticaria is ruled out, some the following laboratory tests may be obtained to determine a cause: CBC, ESR, ANA, thyroid function studies, stool examination for ova and parasites, hepatitis-associated antigen test, assessment of the complement system, and RAST test for immunoglobulin E antibodies



Management



  • Antihistamines (see under Acute Urticaria above)


  • Systemic steroids are sometimes helpful for temporary relief but should be used with caution


  • Food testing and elimination diets are rarely helpful


  • Montelukast (Singulair), a leukotriene receptor antagonist, has also been used for urticaria


  • Cyclosporine and mycophenolate mofetil (CellCept) have demonstrated temporary improvement


  • The biologic omalizumab (Xolair) has also shown positive results with chronic idiopathic urticaria; however, urticaria has tended to recur. It should be administered with caution in regard to rare cases of anaphylaxis


helpful hintsHelpful Hints



  • Aspirin/NSAIDs, opiates, and stress tend to exacerbate CIU


  • Determining an underlying cause for CIU is often a futile search







Clinical Variants

Physical urticaria is diagnosed by challenge testing. The following is a list of some of the physical urticarias and their causes:



  • Dermatographism (“skin writing”): urticaria that results from firm stroking or from scratching the skin. It can also be elicited by wearing tight garments (e.g., bras) (Fig. 11-13)


  • Cold urticaria: itchy hives occur at sites of cold exposure caused by cold winds or immersion in cold water


  • Solar urticaria: from sun exposure (Fig. 11-14, A and B)


  • Cholinergic urticaria: brought about by heat or exercise


Tinea Corporis



Tinea corporis (“ringworm”) is most often acquired by contact with an infected human or animal, usually kittens and occasionally puppies (see also Cheeks). It also may spread from skin-to-skin contact via transmission from wrestling (tinea gladiatorum) or other activity. Acquisition of infection may also occur via secondary spread from one’s own body from other sites of dermatophyte infection (e.g., scalp, feet).


Distinguishing Features



  • Lesions often annular with peripheral enlargement and central clearing (Fig. 11-15)


  • Begins as a pruritic, circular or oval, erythematous, scaling patch or plaque that spreads centrifugally


  • Central clearing follows, while an active, advancing, raised border remains. The result is an annular (ring-shaped) plaque from which the disease derives its common name (“ringworm”)


  • Single or multiple lesions


  • May be pruritic or asymptomatic














Diagnosis



  • A history of a newly adopted kitten, or of another infected contact, is helpful


  • Diagnosis is confirmed by a positive potassium hydroxide (KOH) examination or fungal culture best taken from the “active border” of a lesion or from periodic acid-Schiff stain on biopsy specimens


  • A fungal culture is an alternative, albeit slower, method for diagnosis



Management



  • Topical antifungal agents such as ketoconazole 2% cream twice daily


  • Systemic antifungal agents such as terbinafine (Lamisil), itraconazole (Sporanox), ketoconazole, or griseofulvin are sometimes necessary


  • If pets appear to be the source of infection, they may also need antifungal treatment after evaluation by a veterinarian


Acute Lyme Disease



Acute Lyme disease (LD), or Lyme borreliosis (LB), is a systemic infection caused by the spirochete, Borrelia burgdorferi. Most cases occur from late spring through early fall, because that is when ticks in the nymphal stage are seeking a blood meal. The probability of a tick bite—and thus, the likelihood of contracting Lyme disease—is highest in persons who spend time outdoors, particularly in wooded, brushy, or grassy habitats, in a geographically endemic area.

The bacteria are introduced into the skin by a bite from an infected Ixodes tick. The ticks cling to vegetation (not trees) in grassland, marshland, and woodland habitats. They transfer to animals and humans when there is brushing against the vegetation.

Transmission of the spirochete requires 48 to 72 hours, thus affording the tick (usually the larva or nymph) enough time to embed in the skin. The tick must stay attached for at least 24 hours for infection to occur. Once in the skin, the spirochete may stay localized at the site of inoculation, or it may disseminate via the blood and lymphatic glands. Hematogenous dissemination can occur within days or weeks of the initial infection. The organism can travel to other areas of the skin, the heart, the joints, and the central nervous system.

The tick vector, Ixodes dammini, is found in the northeastern and midwestern United States, where most cases are reported. Ixodes scapularis is the tick in the southeastern United States, Ixodes pacificus on the Pacific coast, and Ixodes ricinus, the sheep tick in Europe, are also vectors.


Distinguishing Features


Initial Phases



  • Initially, the LB lesion is a red macule or papule at the site of a tick bite. The bite itself usually goes unnoticed. Approximately 2 to 30 days after infection, the rash appears


  • Common sites are the trunk, groin, and thigh


  • Usually asymptomatic, the initial lesion expands to form an annular erythematous lesion, erythema migrans, which is the classic lesion of LB (Fig. 11-16)


  • Typically measures from 4 to 70 cm in diameter, generally with central clearing


  • The center of the lesion, which corresponds to the putative site of the tick bite, may become darker, vesicular, hemorrhagic, or necrotic













  • Lesions may be confluent (not annular), and concentric rings may form


  • Multiple lesions sometimes occur, likely the result of bacteremia (Fig. 11-17)


  • At the early stage of disease, flu-like symptoms, such as malaise, arthralgias, headaches, and a low-grade fever and chills, may develop


Intermediate, Chronic, and Late Phases



  • Some of the signs and symptoms of LB may not appear for weeks, months, or even years after the initial tick bite and are believed to be caused by immunopathogenic mechanisms. They include arthritis, nervous system problems, Bell palsy, headaches, memory loss, and cardiac dysrhythmias


  • Rarely, a lesion of lymphocytoma cutis or acrodermatitis chronica atrophicans appears



    • Late Lyme disease refers to symptoms, primarily rheumatologic and neurologic, that occur months to years after initial infection



Diagnosis



Early Diagnosis

To diagnose early LB, the following are important:



  • A history of tick exposure or bite in an endemic area


  • Most patients at the erythema migrans stage are seronegative


  • Currently, CDC recommends a two-step testing procedure. The first step typically consists of a screening enzyme immunoassay (EIA) or enzyme-linked immunosorbent assay (ELISA); if results are positive or equivocal, a Western immunoblot test is performed to confirm the results. Testing should be repeated after about 1 month if negative, because the test may be negative shortly after exposure



Management


Tick Recognition



  • Ixodes ticks are much smaller than dog ticks. In their larval and nymphal stages, they are no bigger than a pinhead


  • Unengorged adult ticks are the size of the head of a match (Fig. 11-18)


Tick Removal



  • An attached tick should be removed carefully by using a pair of tweezers. The tick should be grasped by the head (not the body) as close as possible to the skin, to avoid force that may crush it



Treatment

Oral antibiotics are effective. The duration of recommended therapy ranges from 10 to 30 days. Use one of the following:



  • Doxycycline (100 mg twice per day for 21 days [do not use in children younger than 10 years or in pregnant women]) or


  • Amoxicillin (500 mg three times per day for 21 days) or


  • Ceftriaxone (Ceftin) or cefuroxime (500 mg twice per day for 21 days [expensive; use if patient is unable to tolerate the other antibiotics])


  • Azithromycin (Zithromax) and erythromycin: second-line drugs that should be considered for those who are allergic to beta-lactam antibiotics



Prevention



  • People who are outdoors in endemic areas in the summer should wear long pants and socks, use insect repellents, and frequently examine themselves and their clothing for ticks


  • Doxycycline: a single dose of 200 mg given in less than 72 hours of tick removal is reported to prevent the disease


helpful hintHelpful Hint



  • In endemic areas, patients with probable erythema migrans and a recent source of tick exposure should be started on treatment without blood tests.