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126 CHAPTER 6: The Skin and Nails
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Long, narrow nail plates. In eunuchoidism and hypopituitarism the nails
are long and narrow resembling those in Marfan syndrome.
Longitudinal ridging in nail plate—reedy nail.
there is no diagnostic signicance (Fig. 6-13C).
Friable nail plates.
soft, and the edges frayed (Fig. 6-13D).
Foot and Toenail Signs.
Callus. Well circumscribed areas of thickened epidermal keratin develop
at points of repeated pressure or friction. Callus normally underlies the rst
and fth metatarsal heads and heel. Callus elsewhere, usually accompanying
smaller normal calluses, indicates unusual weight distribution or pressure
from footwear. Calluses, infrequently painful in themselves, cause pain when
hard callus transmits pressure to tissues impinged between callus and underlying bone. Unlike warts, calluses preserve skin lines.
Hard corn. Tight footwear puts pressure on skin overlying bone between
toes producing a conical callus pointing into the dermis. Pressure produces
pain. The central core is seen when the top is pared away.
Soft corn. This is an interdigital corn macerated by moisture and infection.
It is quite painful.
Plantar wart.
lines are disrupted and black dots from hemorrhage are common. Weight
bearing causes pain.
Neuropathic ulcer. Normal pressure and pain sensation protect the foot from
excessive and prolonged pressure over boney prominences. In the insensitive
foot (e.g., diabetic neuropathy) pressure leads to painless ischemic soft tissue necrosis, infection, and/or ulceration. A punched-out, indolent, painless
ulcer develops under a metatarsal head, at the tip of a toe, over the proximal
inter-phalangeal joint of a hammertoe, or on the heel. Test pressure sensation with graded monolament (Chapter 14, page 645). If bone is exposed or
reached by probing, osteomyelitis is likely.
With radiation injury, growth is stunted, the nail plate is
Warts are caused by human papilloma virus infection. Skin
An exaggeration of normal,
Ingrown toenail. Excessive transverse nail plate growth folds the lateral
edge pinching the nail fold.
affected. An ulcer forms by repeated trauma and infection. Weight bearing is
painless, but nail plate pressure is tender. Exuberant granulation tissue may
form in the nail fold.
Subungual pain—subungual exostosis.
sal distal phalanx penetrates the distal nail bed and nail plate. The great toe
is usually involved. Early, a painless discoloration is visible under the nail.
Later, the nail is pushed up and splits.
Toenail overgrowth—Ram's horn nail. The nail is thickened, conical, and
curved like a Ram’s horn.
Most commonly the lateral great toe nail fold is
An exostosis arising from the dor-
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Vascular Signs.
Pallor. Normal skin and mucous membranes are pink due to the dense net-
work of subcutaneous capillaries containing red blood. Pallor is the absence
of normal pink color of skin and mucous membranes, regardless of the cause.
Inspect the conjunctivae, oral mucosa, palmar creases, and nail beds. Pallor
occurs with edema surrounding supercial blood vessels, vasoconstriction,
anemia, and any combination.
CLINICAL OCCURRENCE: Localized Pallor: Cold exposure, vasoconstric-
tion (e.g., Raynaud phenomenon), arterial insufciency, edema; Generalized
Generalized vasoconstriction—cold exposure, severe pain, hypogly-
Pallor:
cemia, volume depletion, or low cardiac output; Chronic Pallor: Normal
in some persons, anemia, renal failure; Paroxysmal Pallor: Apneic periods
in periodic breathing, hypertensive periods from pheochromocytoma, vertiginous periods in Ménière disease, migraine; Obscuration of Skin Vessels:
Edema, myxedema, scleroderma.
Cyanosis.
Cyanosis, the blue skin and mucous membrane color, becomes
evident when capillary blood reduced hemoglobin concentration is >4.0–5.0
g/dL, or contains >0.5–1.5 g of methemoglobin, or >0.5 g of sulfhemoglobin.
The oxyhemoglobin content does not affect color. Local cyanosis occurs when
venous blood is deoxygenated in vessels from stasis or in tissues following
extravasation.
Generalized cyanosis is seen in the lips, nail beds, ears, and
malar regions. DDX: Central cyanosis becomes more prominent with exertion
or in warm environments. Pressure, by emptying venules, capillaries, and
arterioles, blanches cyanosis distinguishing cyanosis from argyria.
CLINICAL OCCURRENCE: Local Cyanosis: Localized venous stasis or arterial
obstruction, Raynaud phenomenon, blood extravasations into supercial tissue;
Central Cyanosis: Hypoxemia (right-to-left shunt, impaired oxygenation from
lung disorders), abnormal hemoglobins (methemoglobin or sulfhemoglobin);
Peripheral Cyanosis (normal arterial oxygen content but increased local oxygen
extraction because of sluggish capillary ow): Cutaneous vasoconstriction sec-
ondary to cold exposure, reex response to decreased cardiac output.
Abnormal nailfold capillaries—scleroderma. Episodic digital vasospasm is
common in scleroderma (Raynaud phenomena) and in otherwise normal persons (Raynaud disease). Abnormal nailfold capillaries are strongly associated
with later appearance of scleroderma. They also can be seen in dermatomyositis and polymyositis.
Arterial circulation signs. Normal skin temperature indicates adequate arterial ow. Normal nail beds are red or pink. If warm feet have blue nail beds,
heat has been applied to feet with inadequate arterial ow. Signs of poor
arterial ow must be distinguished from those of impaired venous return.
Arterial decits cause dermal pallor, coldness, and tissue atrophy. Smallvessel disturbances are recognizable as specic patterns in the skin. Diseases
of larger arteries cause regional hypoperfusion. Conditions which affect
smaller vessels, such as vasculitis, tend to be more diffuse.
Skin pallor and coldness—chronic arterial obstruction. See Chapter 8, page
338. Pallid cool skin suggests regional hypoperfusion. Though normal in cold
environments, it should rapidly resolve on warming.
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A.
B.
FIG. 6-16Circulation of the Skin in the Extremities. A. Dependent rubor. The legs are dependent to observe
the color of the skin and nail beds. Arterial deficit produces a violaceous color from pooling of the blood in the venules.
B. Elevation produces blanching. While the patient is supine, the foot is elevated above the level of venous pressure
(15 cm [6 in.] above the rig ht heart or 25 cm [10 in.] above t he table when t he patient is su pine). Elevation drai ns the foot of
venous blood, so the skin color reflects only the presence of arterial blood. Compare elevated leg with the opposite extremity.
C. Elevating the hand to asses arterial flow. The hand is raised above heart level so that skin color is produced
exclusively by arterial blood.
C.
Dependent rubor and coldness—chronic arterial insufciency. The skin and
nail beds are blue or purple because arterial ow is not displacing deoxygenated blood from venous capillaries. Raise the part above heart level draining
away blue venous blood unmasking pallor of arterial insufciency (Fig. 6-16).
When the part is lowered, the pink color returns in ≤20 seconds. Color return
in ≥45–60 seconds conrms arterial insufciency. See Chapter 8, page 339.
Acute pain, pallor, and coldness.
Acute occlusion of a major peripheral ar-
tery causes skin and nailbed pallor, decreased temperature, and ischemic
pain. See Chapter 8, page 339.
Malnourished skin. The thin skin appears shiny with nely textured wrinkles when pinched. Normal epidermal furrows are absent. Lanugo hair is
absent from the backs of hands, feet, and toes.
Skin scars. Skin on the arms and legs contains atraumatic round scars covered with atrophic skin (Fig. 6-17A) resulting from obstruction of small arteries.
Malnourished nails. The nails grow slowly or not at all. They are dry, brittle,
and contain transverse ridges. Later, they become thickened (Fig. 6-17B).
Skin ulcers. Ischemic ulcers occur over the tips of the toes, malleoli, heels,
metatarsal heads, and dorsal arches. Called cold ulcers, they lack the warm,
red coloration that are characteristic of ulcers caused by infection. The borders
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A
B
C
FIG. 6-17
dermal atrophy, with or without pigmentation resulting from small superficial infarctions. B. Dystrophic nails. The toenails
grow more slowly than normal, and the nail plates become thickened and laminated, the layers forming transverse ridges.
C. Necrosis. Gangrene of the distal parts may develop from arterial deficit. The sketch shows a round spot of gangrene on
the tip of the great toe, and the middle toe blackened from dry gangrene.
Dermal Lesions from Arterial Deficit. A. Atrophy. The skin over the legs contains round areas of
frequently appear punched out. They are also seen in sickle cell disease and
diabetes mellitus with severe neuropathy.
Retiform necrosis.
Necrotic skin in an angulated, stellate (retiform) pattern
suggests obstruction of a dermal arteriole; suspect vasculitis.
Skin gangrene.
Initial lesions are round, <1 mm in diameter, with pitted cen-
ters of black skin (Fig. 6-17C). Gangrene may spread to involve an entire foot.
When the skin is black, wrinkled, and dry, the term is dry gangrene. Infection
is associated with swelling oozing of uid, wet gangrene.
Nodular vessels. —polyarteritis nodosa. See Chapter 8, page 362.
Purpura, intradermal hemorrhage.
In general, mucocutaneous bleeding
occurs with platelet abnormalities (number or function) or vessel wall problems (e.g., scurvy). Bleeding into joints or viscera is likely related to clotting
factor deciencies or inhibitors. Blood extravasating into the skin is rst red,
then blue. Within days, hemoglobin degrades changing the color to green or
yellow before fading. Pressure does not blanch the area.
Petechiae are discrete
round hemorrhagic areas <2 mm in diameter. Larger spots are ecchymoses.
When occurring in groups the term is purpura. Purpuric lesions can become
conuent, usually without elevating the skin or mucosa (macules and patches).
Spontaneous purpura is most common on the lower legs. Minor trauma can
induce it
mucosa elevation. Extravasated blood dissects along tissue planes.
elsewhere. A hematoma is a hemorrhagic nodule causing skin or
DDX:
Infectious purpura may predominate on the thorax and abdomen. Palpable
purpura suggests vasculitis. Larger nodules may be palpable in polyarteritis
nodosa. In subacute bacterial endocarditis septic emboli cause petechiae anywhere. Petechiae can be distinguished from small angiomas by not blanching
under pressure.
CLINICAL OCCURRENCE: Vascular Abnormalities: Eroded or trauma-
tized large vessels, hereditary hemorrhagic telangiectasia, vasculitis, infections (Rocky Mountain spotted fever), scurvy, Schamberg disease, Cushing
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syndrome; Hematologic Abnormalities—Quantitative Platelet Defects:
Autoimmune thrombocytopenic purpura, heparin-induced thrombocytopenia, hypersplenism; Qualitative Platelet Defects: Aspirin, von Willebrand
disease, Glanzmann syndrome, thrombotic thrombocytopenic purpura
(TTP), bone marrow failure (e.g., aplastic anemia, leukemia, chemotherapy),
meningococcemia, cryoglobulinemia, disseminated intravascular coagulation (DIC).
Nonpurpuric vascular lesions.
Flushing and blushing. Episodic and often paroxysmal dilation of cutaneous
arterioles oods the capillaries causing reddening of the involved skin. Flush-
ing is more generalized than blushing which is limited to the head, neck, and
upper chest. DDX: Blushing is usually very situational and transient. Flushing
may or may not have a trigger and is more sustained. Generalized erythroderma does not have a trigger and is persistent.
CLINICAL OCCURRENCE: Flushing: Rosacea, carcinoid syndrome, pheo-
chromocytoma, fever, hot environments, generalized erythrodermas (toxic
shock syndrome, drug eruptions, SLE); Blushing: Emotional triggers, for
example, embarrassment, shame, fear.
Arterial spider (spider angioma, spider telangiectasia). A coiled arteriole
arising perpendicularly from a deeper artery ends in horizontally radiating
branches in the plane of the skin. The ery red vascular gure has a central
area, varying from a pinpoint to a papule from which radiate arterialized capillaries forming the spider legs (Fig. 6-18D). The vessels may dip into the tissue
to reappear further on, forming short, visible segments. An area of erythema
surrounds the body and extends several millimeters beyond the radicular
tips. Rarely, the body is visibly pulsatile, and pulsation may be felt. Pressure
over the body with a glass slide shows the blood emerging from the punctum
in pulses. Pressing the body with a pencil tip fades the radicles which ll centrifugally when pressure is released. Spiders commonly occur on the face and
neck and, in diminishing frequency, on the shoulders, anterior chest, back,
arms, forearms, and backs of the hands and ngers. Spiders are rare below the
umbilicus. In liver disease and pregnancy, they are frequently accompanied
by palmar erythema. The most common causes of arterial spiders include
high esterogen states including chronic liver disease with cirrhosis, hyperestrinism, pregnancy (disappearing after delivery) and, occasionally, following
signicant cumulative sun exposure.
Reticular pattern—livedo reticularis. Skin on the arms and legs is mottled with circinate bands of cyanosis surrounding patches of normal skin
(Fig. 6-18E, Fig. 6-19). Three types are described. In cutis marmorata the mottling appears on exposure to cold and disappears with warming. Livedo re-
ticularis idiopathica, which is not associated with other disease, and also can
improve with rewarming, whereas livedo reticularis symptomatica persists, and
is a frequent accompaniment of the antiphospholipid syndrome, cryoglobulinemia, and polyarteritis nodosa. Ulceration sometimes complicates those that
persist with warming. Livedo reticularis is seen with atheroemboli (page 153).
Palmar erythema. Fixed, diffuse erythema involves the hypothenar eminence and, with less intensity, the thenar prominence (Fig. 6-18F). In severe
D. Arterial spider E. Livedo reticularis F. Palmar erythema
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A. Caviar lesions
of tongue
Blue
Red
punctum
B. Scrotal venous
angiomas
mottling
Blue
C. Glomus tumor
under nail
FIG. 6-18Some Named Superficial Vascular Lesions. A. Caviar Lesions of the Tongue. Varicose veins
under t he tongue for m bluish mas ses that app ear as bunche s of caviar. B. Scr otal venous ang iomas. When the scrotum
is sprea d, multiple dark red or blue papules, 3 –4 mm in diamet er, are se en. C. Glomus tumor under the nail. An ele-
vated n odule, 2–10 mm in diameter, ma y occur any plac e in the skin, fre quently un der the nail pl ate. It is extre mely painf ul.
D. Venous stars and arterial spiders. One form of venous star is depicted; the lesions may also appear as cascades,
flares, rockets, comets, or tangles. A typical form of arterial spider, with punctum and radicles, is presented. While venous
stars are bluish, spiders are fiery red. Both lesions fade with pressure. Pressing the center with a pencil tip will not blanch
the branches of a star; the radicles of the spiders will fade with pressure on the punctum. The star always overlies a large
vein; the spider is not associated with a visible large vessel. As seen through a pressing glass slide, the venous star does
not pulsate; the arterial spider fills from the center with pulsatile spurts. E. Livedo reticularis. Seen most often on the
legs, the skin is mottled, with deeply cyanosed areas interspersed with round pale spots. In one type, the discoloration
disappears with warming; in others, it does not. F. Palmar erythema. There is intense diffuse erythema which is
deepest over the hypothenar eminence and less pronounced on the thenar eminence and distal fingers. The erythema is
not mottled.
FIG. 6-19Livedo Reticularis. The netlike pattern of dilated cutaneous veins is readily apparent on both thighs.
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cases, the palmar surfaces of the digits and thumb are similarly reddened.
Examples:
Erythroderma.
inammation, fever, and/or release of bacterial toxins and involves over 80%
to 90% of the body. The patient presents with generalized cutaneous erythema.
Asymptomatic in benign conditions, it is intensely painful and burning with
systemic inammation (Fig. 6-20).
tococcal toxic shock syndrome, staphylococcal scalded-skin syndrome, scarlet fever, drug eruptions (exfoliative dermatitis), Stevens–Johnson syndrome,
toxic epidermal necrolysis, psoriasis, SLE, cutaneous T-cell lymphoma.
Acute generalized exanthematous pustulosis (AGEP). Acute generalized
erythroderma is accompanied by fever, chills, and leukocytosis. The erythroderma progresses over hours to widespread pustulosis. The condition is
self-limited and appears to follow exposure to viruses or certain drugs, e.g.,
NSAIDs.
Pink papules—rose spots of typhoid fever.
ules 2–4 mm in diameter that blanch with pressure. They appear in the second
week, usually in crops, commonly on the upper abdomen and lower thorax.
Each lesion persists for 2–3 days, then disappears leaving a faint brown stain.
Red macule or papule—cherry angioma (papillary angioma). Usually <3 mm in
diameter and often no larger than a pinhead, the cherry angioma is bright red,
discrete, and irregularly round, surrounded by a narrow halo of pallid skin.
Larger lesions may be slightly elevated. Occasionally they are pedunculated.
Liver disease; pregnancy, disappearing after delivery.
Diffuse dilation of cutaneous capillaries accompanies systemic
CLINICAL OCCURRENCE: Fever, viral exanthems, staphylococcal or strep-
Rose spots are erythematous pap-
FIG. 6-20Erythroderma. There is diffuse, generalized cutaneous capillary dilation which blanches with hand pressure.
This patient’s erythroderma is due to systemic lupus erythematosus.
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Pressure causes little or no blanching. Small lesions may be distinguished from
petechiae only by their permanence when observed for several days. Angiomas occur more often on the thorax and arms than the face and abdomen; they
are less frequent on forearms and on legs. With advancing age, some fade and
become atrophic. Everyone has a few, the number increases after age 30 years.
They have no clinical signicance.
Blue papule—venous lakes.
Gentle pressure empties them leaving lax indentations beneath skin level.
They rarely occur before age 35 and increase with age. Associated with sun
exposure they are much more common in men than women. Lakes are more
frequent on ears and facethan on the lips and neck; they are uncommon elsewhere.
Blue papules—scrotal venous angioma (Fordyce lesion). Figure 6-18B and
Chapter 12, page 518.
Blue nodule—rubber-bleb nevi of skin and gastrointestinal tract.
three types of lesions: a large disguring angioma, a uctuant thin-skinned
bleb containing blood that leaves a rumpled sac when compressed, and an
irregular blue area gradually merging with surrounding skin and only partially fading with pressure. Similar lesions in the gut are a risk for serious
hemorrhage. The skin lesions may be few or many scattered over the body.
The condition is not hereditary.
Painful red or blue nodule—glomus tumor. Glomus tumors are more common in the hands and ngers, especially beneath a nail (Fig. 6-18C). The tumor is a red or blue elevated nodule 2–10 mm in diameter. It is exquisitely
painful, completely disproportionate to its size. The pain may occur in paroxysms. Relief may require surgical excision.
Irregular spongy tumor—cavernous hemangioma. The tumor occurs in any
tissues and varies in size from microscopic to involvement of an entire arm
or leg. Usually present at birth and enlarging with age, it can involve skin,
subcutaneous tissue, muscle, and even bone. The surface is irregular, nodular,
frequently bluish, and uctuant. Raising the involved limb may cause partial
emptying. Hemangiomas can consume platelets and coagulation factors producing a DIC picture (Kasabach–Merritt syndrome).
Thin-walled papules ll with venous blood.
There are
Stellate gure—venous star.
obstruction, small supercial veins radiate from a central point (Fig. 6-18D).
Patterns include stars, angular Vs, cascades, ares, rockets, and tangles varying from a few millimeters to several centimeters in diameter. Venous stars
are more common in women. Common sites are the top of the foot, leg, medial aspect of the thigh above the knee, and back of the neck.
to distinguish venous stars from arterial spiders. Like spider angiomas, the
branches fade with pressure relling from the center after pressure is released, but the vessels are blue-purple, whereas arterial spiders are bright red.
In contrast to arterial spiders, pressure on the central point does not blanch
the radicles. Stars always overlie a larger vein; spiders are not associated with
another vessel.
Occurring with aging or arising from venous
DDX: It is easy
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Reticular pattern—costal fringe. Usually seen with aging in older men, supercial veins near the anterior ribs and xiphoid form networks, sometimes
in bands with rough correspondence to the diaphragm attachments.
Reticular pattern—facial telangiectasis. Vessels on the nose and face dilate
from exposure to wind and cold, and with aging in some persons. They also
occur with rosacea and liver disease.
Reticular pattern—radiation telangiectasis. Therapeutic irradiation produces skin changes months after exposure. The chief signs are pigmentation,
atrophy, and telangiectasias which are the most conspicuous. Fine red or blue
vessels form a disordered network.
Signs of Systemic Lipid Disorders.
Xanthomas. Systemic disorders of lipid metabolism lead to lipid deposition
in cutaneous and subcutaneous structures including tendons. The asymptom-
atic lesions are macules, papules, plaques, or nodules, often brown to orange
in color. Their distribution is highly suggestive of the underlying disorder.
Xanthelasma. There are soft, usually symmetrical, often coalescent elevated
yellow to beige-colored plaques on the eyelids, increasingly common after
age 60. It may occur in otherwise normal people and with elevated lowdensity lipoprotein cholesterol.
Eruptive xanthomas. Hypertriglyceridemia leads to rather sudden appearance of multiple closely packed yellow to red-to-brown cutaneous papules and
nodules. Most common on the elbows and buttocks, they may occur anywhere.
Palmar xanthomas. The inltration of the hand’s creases producing yellowish ridges is pathognomonic for familial dysbetalipoproteinemia.
Tendon xanthomas.
ligaments, particularly the Achilles and hand tendons, associated with markedly elevated serum cholesterol.
Relatively large nodules are palpable along tendons and
SKIN AND NAIL SYNDROMES
Common Skin Disorders:.
Acne vulgaris. Androgens promote sebaceous gland obstruction, and
Propionibacterium acnes proliferate within the pilosebaceous unit. Lesions
are distributed with sebaceous glands on face, chest, and upper back.
Uninamed comedones are either open to air oxidizing sebum in orice (a
blackhead) or closed producing a white papule. Rupture of the obstructed
pilosebaceous unit leads to inammatory papules, pustules, and nodules.
Rosacea. Patients develop inamed papules and telangiectasia on the forehead,
cheeks, and chin progressing to chronic edema and thickened skin. Women are
more affected than men, although rhinophyma is more common in men.
Eczema—Dermatitis. Dermatitis literally means skin inammation,
in practice it is synonymous with eczema a specic class of epidermal
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inammation. Several types are distinguished by their etiology, pattern,
and appearance.
Atopic dermatitis.
with seasonal allergies, asthma, or atopic dermatitis.
fancy or childhood and may be lifelong. Lesions are erythematous intensely
pruritic papules or plaques usually on exor surfaces of elbows, neck, and
wrists, and face, feet, and hands. Scratching temporarily relieves the itch, but
increasing inammation and pruritus producing lichenication.
Lichen simplex chronicus. Chronic rubbing or scratching produces intensely
pruritic hyperkeratotic plaques. Nodular lesions, prurigo nodularis, occur with
persistent picking.
Dyshidrotic eczema. Deep pruritic vesicles coalesce on hands and feet, especially intertriginous areas, palms, and soles. Scratching produces lichenication. DDX: Consider contact allergens and autosensitization dermatitis from
dermatophyte infection of the feet (id reaction).
Asteatotic eczema.
like a drying lakebed, with erythematous margins and commonly marginal
scaling. Intensely pruritic, it is common on extremities and trunk in cold dry
climates and exacerbated by use of soap and water.
Papular eczema.
tremities. DDX: Guttate psoriasis is similar but has supercial scale.
Nummular eczema.
with sharp borders and a raised edge, most common on the legs and trunk of
older men. They may weep, especially with excoriation.
Stasis dermatitis. Increased venous and capillary pressure produces
inammation, edema, subcutaneous brosis, and skin atrophy with hemosiderin staining. Pitting edema, erythema, and warmth, often with tenderness, are prominent. Chronically, subcutaneous tissues become brotic and
the edema no longer pits (brawny edema or lipodermatosclerosis). The skin
thins and is easily injured leading to ulcers and secondary infection. DDX:
When erythema and warmth are present it can be confused with cellulitis.
Common in rst-degree relatives, it is often associated
Atopy begins in in-
Dry skin is cracked into irregular rhomboidal plates,
The lesions are pruritic erythematous papules on the ex-
The nummular (coin-like) lesions are 1–3 cm plaques
Contact dermatitis.
tion or an inammatory response to skin irritants. Irritant contact dermatitis
can occur in anyone, e.g., chemical burns. Allergic contact dermatitis requires
prior exposure with sensitization. The lesions are erythematous intensely
pruritic plaques. The distribution lesions and exposure history are critical for
correct diagnosis (Fig. 6-21).
(but so does rhus dermatitis) and evolves more rapidly than allergic disease.
CLINICAL OCCURRENCE: Allergic: rhus dermatitis (poison ivy and oak),
many other plant and animal sources, drugs (neomycin, sulfonamides), chromate, solvents, latex, metals especially nickel (common in earrings, buckles,
snaps), cosmetics, clothing dyes, industrial oils, and many others; Irritants:
acids and alkali, cement, solvents, cutting oils, detergents, etc.
This is either a cell-mediated response to prior sensitiza-
DDX: Irritant disease often has early vesiculation
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