| Inflammatory |
| Asteatotic dermatitis | Common M > F Age: typically >60 years | Pruritus and dry skin Waxing and waning course Worse in winter | Dry, fissured, cracking, mildly scaly and inflamed plaques on bilateral anterior lower legs (Figure 8-3) |
| Stasis dermatitis | Common F > M Age: middle-aged and elderly adults | Asymptomatic or pruritic Associated with leg swelling | Erythematous, scaly plaques, may be hyperpigmented, lichenified, or sclerotic on bilateral anterior lower legs, especially medial ankles (Figure 29-1) |
| Nummular eczema | Common M > F Age: Adults | Pruritus Chronic, waxing, and waning course Worse in fall and winter | Round, light pink, scaly, thin, 1-3 cm plaques on legs (Figure 8-11) |
| Psoriasis vulgaris | Common M = F. Onset at any age but peaks in 20s and 50s | Asymptomatic to mildly pruritic. Chronic course. May be associated with arthritis Family history of psoriasis | Red papules and plaques with silvery, thick, adherent scale, commonly on knees (Figure 9-1) |
| Erythema nodosum | Uncommon F > M Age: 20-40 years | Tender lesions Variable course May be associated with fevers and arthralgias | Indurated, tender, red, deep, poorly defined nodules, usually on bilateral shins (Figure 24-14) |
| Pyoderma gangrenosum | Rare F ≥ M Age: all ages, but typically 30-40 years | Painful. May last months to years Spontaneous healing may occur | Initially, a hemorrhagic pustule with surrounding erythema. Later, ulceration with granulation tissue, eschar and purulent material at the base, and a dusky red/purple border (Figure 2-13) |
| Infectious |
| Cellulitis | Common M = F Age: more common in older adults | Pain, swelling, fever, chills, and malaise Increased risk in diabetics | Localized warm, red, tender plaque with ill-defined borders, usually on lower leg (Figure 12-3) |
| Tinea corporis | Common M > F Age: any age | Mild pruritus History of concomitant tinea pedis | Solitary or grouped, well-demarcated red annular plaques with a raised border and peripheral scale (Figure 10-4). Sometimes peripheral vesicles or pustules |
| Neoplastic |
| Stucco keratoses | Common M > F Age: older adults | Asymptomatic and usually unnoticed | Keratotic, stuck on appearing, whitish-grey papules bilaterally on extensor surface (Figure 16-3) |
| Systemic |
| Diabetic dermopathy | Uncommon M:F unknown Age: usually >50 years | Asymptomatic Appears in crops. Slowly resolves with scarring | Well-circumscribed, round, atrophic, and hyperpigmented plaques that heal with scarring on bilateral shins |
| Necrobiosis lipoidica | Uncommon F > M Age: young adults | Usually asymptomatic, but may ulcerate and become painful. Gradual onset, may last years. One-third have history of diabetes or minor trauma | Well-demarcated, shiny plaque with a mildly elevated erythematous border and an atrophic, yellowish, waxy center on bilateral shins (Figure 24-8) |
| Thrombocytopenic purpura (TTP) | Uncommon M = F Age: any age, depending on etiology | Asymptomatic Onset: hours Associated with low platelets due to HIV, TTP, ITP, DIC, drugs, infections, and bone marrow dyscrasias | Petechiae: pinpoint, nonblanching, nonpalpable red macules (Figure 25-1) Ecchymosis: larger red macules and black-and-blue patches |
| Vascular |
| Superficial thrombophlebitis | Uncommon M:F unknown Age: young to middle aged adults | Asymptomatic or tender Idiopathic or due to trauma, infection, IV extravasation, or migratory thrombophlebitis | Red and tender subcutaneous cord with swelling along the course of a vein Can occur on the trunk or extremities, but most commonly occurs on the legs |
| Leukocytoclastic vasculitis. | Uncommon M = F Age: all ages | Asymptomatic, pruritic, or tender. Duration: days to years depending on etiology. Idiopathic or due to drugs, underlying CVD, infections, or malignancy | Classic presentation is palpable purpura/petechiae with bright red well-defined macules and scattered red papules on lower legs and ankles (Figure 25-4) |
| Pigmented purpuric dermatosis (Schamberg's disease) | Common M > F Age: typically 30-60 years | Asymptomatic or mildly pruritic. Slowly evolving over months. Chronic course, lasting years | Characteristic purpuric, speckled, "cayenne pepper-like" macules or less commonly annular plaques and lichenoid papules on lower legs |
| Physiologic livedo (cutis marmorata) | Common M:F unknown Age: more apparent in neonates, infants, and children | Asymptomatic A physiologic phenomenon that occurs in the cold | Purple discoloration of the skin in a netlike distribution on the lower extremities that resolves with warming |
| Primary and secondary pathologic livedo reticularis (LR) | Uncommon M < F Age: 20-30 years of age | Asymptomatic. Secondary LR is associated with conditions that cause vasospasm, increased blood viscosity, vasculitis, or intravascular obstruction | Purple discoloration of the skin in a netlike distribution on the lower extremities that persists after rewarming (Figure 2-28) |