Tumors:
(1) basal cell carcinoma
(2) squamous cell carcinoma
(3) malignant melanoma
(4) skin adnexal tumors
(5) lymphoma or leukemia cutis
(6) Langerhans cell histiocytosis
Infections:
(1) Staphylococcus aureus
(2) Streptococcus pyogenes
(3) Lyme disease
(4) syphilis
(5) sporotrichosis, cryptococcosis, histoplasmosis or other deep fungal infection
(6) leishmaniasis
(7) Herpes simplex or Herpes zoster
(8) Pseudomonas aeruginosa and Ecthyma gangrenosum
(9) septic embolism
(10) myobacterial infection (M. tuberculosis, atypical)
(11) cutaneous anthrax
(12) tularemia
(13) rickettsial infection
(14) necrotizing cellulitis
(15) other infection
Toxic:
(1) chemical burn
(2) poison ivy or poison oak
(3) necrotic arachnidism due to another genus of spider
(4) bee or wasp sting
Rheumatologic or vascular:
(1) Wegener's granulomatosis
(2) Takayasu's arteritis
(3) polyarteritis nodosa (PAN)
(4) leukocytoclastic vasculitis
(5) cryoglobulinemia
(6) calcific uremic arteriolopathy
(7) livedoid vasculopathy
(8) antiphospholipid antibody syndrome
(9) small vessel occlusive arterial disease
Skin lesions:
(1) pyoderma gangrenosum
(2) lymphomatoid papulosis
(3) pemphigus vegetans
Other:
(1) factitious injury
(2) pressure ulcer
(3) diabetic ulcer
(4) radiation injury
(5) burn
(6) venous stasis ulcer
(7) trauma
(8) insect bite
(9) foreign body
