A. Palpable Purpura

1. Gonococcemia
2. Meningococcemia
3. Vasculitis
   1. Purpura Group: Henoch-Schonlein, Hypersensitivity, Cryoglobulinemia
   2. ANCA+ Group: polyarteritis nodosa, Behcet's Disease
4. Drug Hypersensitivity - especially hydralazine, procainamide, sulfa drugs
5. Cholesterol Emboli
6. Rocky Mountain Spotted Fever
7. Cardiac Myxoma

B. Non-Palpable Purpura

1. Disseminated Intravascular Coagulopathy
2. Subacute Bacterial Endocarditis
3. Vitamin C Deficiency - Scurvy

C. Vesicles and Bullae

1. Erythema Multiforme - target lesions
2. Stevens-Johnson Syndrome - target lesions with mucocutaneous vesicular eruptions
3. Toxic Epidermal Necrolysis
4. Staphylococcal scalded skin syndrome (S. aureus)
5. Pseudomonas Sepsis - pyoderma gangrenosum
6. Pemphigus Vulgaris bullae not easily extended
7. Bullous pemphigoid - rare disease; bullae easily extended)

D. Cellulitis [1]

1. Common
   1. Deep vein thrombosis
   2. Superficial thrombophlebitis
   3. Contact dermatitis
   4. Insect stings
   5. Drug reactions
   6. Eosinophilic cellulitis (Wells Syndrome)
   7. Gouty arthritis
   8. Foreign body reactions
2. Uncommon
   1. Carcinoma erysipelatoides
   2. Familial Mediterranean fever (FMF)
   3. Urticaria
   4. Lymphedema
   5. Systemic lupus
   6. Sarcoid
   7. Lymphoma / Leukemia
   8. Paget disease
   9. Panniculitis

References

1. Falagas ME and Vergidis PI. 2005. Ann Intern Med. 142(1):47