1. What is the typical rate at which the eruption of cutaneous larva migrans progresses?

a. About 0.5 cm per day

b. About 2 cm per day

c. About 1 cm per week

d. About 5 cm per week

2. Under which of the following circumstances do pruritic urticarial papules and plaques of pregnancy (PUPPP) most commonly occur?

a. Primagravida, first trimester

b. Multigravida, first trimester

c. Primagravida, third trimester

d. Multigravida, third trimester

3. Approximately what percentage of hair follicles are in the active growth (anagen) phase on a normal scalp?

a. 30%

b. 50%

c. 70%

d. 90%

4. Which of the following sutures is associated with the least intense tissue inflammatory response?

a. Nylon

b. Catgut

c. Silk

d. Cotton

5. In a patient with psoriatic arthritis, which of the following features would be an expected finding?

a. Symmetrical joint involvement

b. All of the joints in one digit are affected

c. Initial involvement of five or more joints

d. Affected joints are swollen without erythema

6. Which of the following growths is not classified as a hamartoma?

a. Trichofolliculoma

b. Nevus sebaceous

c. Dermatofibroma

d. Chondroid syringoma

7. By what age does the marked freckling associated with xeroderma pigmentosum most commonly occur?

a. 9 months old

b. 2 years old

c. 5 years old

d. 10 years old

8. Which of the following medications is least likely to place patients at risk for developing Stevens-Johnson syndrome or toxic epidermal necrolysis?

a. Furosemide

b. Sulfamethoxazole

c. Allopurinol

d. Carbamazepine

9. What is the appropriate term for describing excessive longitudinal ridging of the nails?

a. Beau's lines

b. Koilonychia

c. Muehrcke's lines

d. Trachyonychia

10. In which condition would a positive Nikolsky sign not be expected?

a. Porphyria cutanea tarda

b. Staphylococcal scalded-skin syndrome

c. Pemphigus vulgaris

d. Toxic epidermal necrolysis

ANSWERS

1. b. About 2 cm per day. In cutaneous larva migrans, the life cycle of the parasites begins when eggs are passed from animal feces into warm, moist, sandy soil, where the larvae hatch and molt twice before the infective third stage. By using their proteases, larvae penetrate through follicles, fissures, or intact skin of the new host where they shed their natural cuticle and begin migration within a few days. In animal hosts, the larvae are able to penetrate into the dermis and are transported to the lungs where they break through into the alveoli, migrate to the trachea, are swallowed, and mature sexually in the intestine, and their eggs are then excreted. Within humans, the larvae lack the collagenase needed to penetrate the basement membrane and invade the dermis; therefore, the larvae remain limited to the skin. The larvae are acquired through activities such as going barefoot at the beach, playing in sandboxes, carpentry or plumbing under homes, and gardening. The most commonly affected areas are the feet, buttocks, genitals, and hands. Shortly after inoculation, slightly pruritic papules appear, and as the larvae begin to burrow, they create thin, linear, twisting, winding lines. The tortuous linear lesions are often interrupted by papules that mark the site of resting larvae. Migration generally begins 4 days after inoculation, although the larvae may remain quiescent for several days or months. The larvae progress at a rate of about 2 cm per day, and as the eruption advances, old parts tend to fade. If left untreated, the larvae usually die in 2-8 weeks, with resolution of the eruption, although rarely it has been reported to persist for up to 1 year.

James, W. D., Berger, T. G., & Elston, D. M. (2011). Andrews' diseases of the skin: Clinical dermatology (11th ed.). Philadelphia, PA: Saunders/Elsevier; Robles, D. T. (2011). Cutaneous larva migrans. Retrieved from http://emedicine.medscape.com/article/1108784-overview

2. c. Primagravida, third trimester. The term "pruritic urticarial papules and plaques of pregnancy" (PUPPP) was first used by Lawley et al in 1979. The eruption is characterized by erythematous papules and plaques that begin as 1- to 2-mm lesions within the abdominal striae. They then spread over the course of a few days to involve the abdomen, buttocks, thighs, and in some cases, arms and legs. The lesions coalesce to form urticarial plaques, and intense pruritis is characteristic. Most cases occur in primagravidas and rarely recur with subsequent pregnancies. Onset is generally late in the third trimester, and delivery results in resolution. Fetal and maternal outcomes are not affected.

James, W. D., Berger, T. G., & Elston, D. M. (2011). Andrews' diseases of the skin: Clinical dermatology (11th ed.). Philadelphia, PA: Saunders/Elsevier.

3. d. 90%. Approximately 90%-93% of scalp follicles are in the active growth (anagen) phase, which lasts for 2-8 years. Catagen is the involution stage in between the anagen and telogen phases. During this phase, massive keratinocyte apoptosis leads to involution of the lower two thirds of the hair follicle, shortening scalp follicles from 2-5 mm to 0.25-0.5 mm. Most follicles that are not in the anagen phase are in the resting (telogen) phase in which the hairs are prepared for expulsion. Approximately 1% of the telogen follicles are in the exogen phase, meaning that they are shedding their hair shafts.

Goldsmith, L. A., Katz, S. I., Gilchrest, B. A., Paller, A. S., Leffell, D. J., & Wolff, K. (2012). Fitzpatrick's dermatology in general medicine (8th ed.). New York, NY: McGraw-Hill Medical.

4. a. Nylon. Sutures made from natural products like silk, catgut, and cotton are associated with high tissue reactivity (the degree of the tissue's inflammatory response to the suture). Most other sutures are made from synthetic fibers and cause low amounts of tissue reactivity, including nylon (Ethilon, Dermalon, Nurolon, Surgilon), polypropylene (Prolene, Surgilene, Surgipro), and polyester (Dacron, Mersilene, Ethibond) sutures.

New Zealand Dermatological Society Incorporated. (2012). Suture materials. Retrieved from http://www.dermnetnz.org/procedures/sutures.html; Goldsmith, L. A., Katz, S. I., Gilchrest, B. A., Paller, A. S., Leffell, D. J., & Wolff, K. (2012). Fitzpatrick's dermatology in general medicine (8th ed.). New York, NY: McGraw-Hill Medical.

5. b. All of the joints in one digit are affected. Psoriatic arthritis typically manifests with asymmetric joint involvement and commonly affects all of the joints in one digit whereas the others remain free of arthritis. It is an inflammatory arthritis that typically manifests with swelling and overlying erythema of the affected joints. Psoriatic arthritis has a gradual onset and usually begins as an oligoarthritis (four or fewer joints) that may progress to a polyarticular (more than four joints) disease. About half of the affected individuals experience morning stiffness that lasts for more than 60 minutes and gets better with activity. Enthesitis (inflammation at the site of tendon or ligament insertion into the bone) is present in up to 42% of patients and most commonly involves the attachment of the Achilles tendon or the plantar fascia to the calcaneus. Dactylitis (uniform swelling of a digit, also called "sausage digit") occurs in up to 49% of individuals and results from simultaneous involvement of all three joints and tenosynovitis of the involved digit.

Garg, A., & Gladman, D. (2010). Recognizing psoriatic arthritis in the dermatology clinic. Journal of the American Academy of Dermatology, 63(5), 733-748.

6. c. Dermatofibroma. Dermatofibromas are fibrohistiocytic tumors, which, unlike hamartomas, are considered a neoplastic growth. Hamartomas are benign proliferations composed of cellular elements, normal to a given site, in aberrant proportion. Hamartomas can be congenital, such as nevus sebaceous, or acquired, such as trichofolliculoma or chondroid syringoma.

Bolognia, J. L., Jorizzo, J. L., & Schaffer, J. V. (2012). Dermatology (3rd ed.). St. Louis, MO: Elsevier/Mosby.

7. b. 2 years old. In most patients with xeroderma pigmentosum, marked freckling of sun-exposed areas usually occurs before 2 years old. More than half of the individuals with this condition have a history of acute sunburn reaction with blistering or persistent erythema after minimal ultraviolet exposure. Ophthalmologic involvement in xeroderma pigmentosum is almost as common as the cutaneous abnormalities, with the onset of symptoms at around 4 years old. About 30% of patients with xeroderma pigmentosum experience progressive neurologic degeneration. The earliest clinical signs of neurologic involvement are diminished or absent deep tendon reflexes and high-frequency hearing loss. These may occur in infancy or be delayed until the second decade of life. Other neurologic findings include microcephaly, progressive intellectual deterioration, spasticity, ataxia, or seizure. Xeroderma pigmentosum is an example of accelerated photoaging, and among affected individuals who are 20 years old or younger, there is a greater than 1,000-fold increased risk of cutaneous basal cell carcinoma, squamous cell carcinoma, or melanoma. Patients with this condition also have an approximately 10- to 20-fold increase in internal malignancies, including cancer of the brain, lungs, hematopoietic system, kidney, and gastrointestinal tract. More severely affected patients tend to die of neoplastic complications by 20 years old.

Chantorn, R., Lim, H. W., & Shwayder, T. A. (2012). Photosensitivity disorders in children: Part II. Journal of the American Academy of Dermatology, 67(6), 1113.e1-1113.e15.

8. a. Furosemide. Although furosemide has been implicated in a few case studies as a potential cause of Stevens-Johnson syndrome or toxic epidermal necrolysis, it is not considered to be a high-risk medication. These two severe drug reactions are characterized by erythematous macules of the skin and mucous membranes that evolve progressively into confluent flaccid blisters that lead to epidermal detachment. Drugs that are considered to have a high risk for developing this type of reaction include allopurinol, sulfamethoxazole, sulfadiazine, sulfapyridine, sulfadoxine, sulfasalazine, carbamazepine, lamotrigine, phenobarbital, phenytoin, phenylbutazone, nevirapine, oxicam, Nonsteroidal anti-inflammatory drugs, and thiacetazone.

Goldsmith, L. A., Katz, S. I., Gilchrest, B. A., Paller, A. S., Leffell, D. J., & Wolff, K. (2012). Fitzpatrick's dermatology in general medicine (8th ed.). New York, NY: McGraw-Hill Medical.

9. d. Trachyonychia. The term trachyonychia is used to describe rough, often thin, nails because of excessive longitudinal ridging. If all nails are affected, the term "twenty nail dystrophy" is often used. Causes include lichen planus, alopecia areata, psoriasis, and dermatitis. Beau's lines are transverse depressions or grooves that move distally with nail growth. They occur because of the temporary interruption of nail matrix activity. Involvement of a single nail usually indicates trauma, whereas multiple nail involvement indicates a systemic cause such as severe or febrile illness, erythroderma, or certain medications. The term koilonychia refers to thin, concave, spoon-shaped nails that are usually physiologic in children and occupational or associated with iron deficiency anemia in adults. Muehrcke's lines are paired, narrow, white transverse bands, separated from each other and the lunula by strips of pink nail. They are an abnormality of the nail bed that is associated with hypoalbuminemia and chemotherapy and do not grow out with the nail.

Linton, C. P. (2012). Describing nail abnormalities. Journal of the Dermatology Nurses' Association, 4(2), 149-150.

10. a. Porphyria cutanea tarda. The vesicles and bullae of porphyria cutanea tarda result from a subepidermal process and are not associated with a positive Nikolsky sign. Nikolsky sign is positive when lateral pressure on normal-appearing skin at the periphery of active lesions results in shearing away of the epidermis. This easy detachment of the epidermis is noted in blistering disorders in which the pathology is above the basement membrane zone. These conditions include staphylococcal scalded-skin syndrome, pemphigus vulgaris, and toxic epidermal necrolysis.

Goldsmith, L. A., Katz, S. I., Gilchrest, B. A., Paller, A. S., Leffell, D. J., & Wolff, K. (2012). Fitzpatrick's dermatology in general medicine (8th ed.). New York, NY: McGraw-Hill Medical.