see also:

• dermatology
• pustular rashes

• when discussing “nodular rashes” this is generally referring to “panniculitis” (inflammation of the subcutaneous tissue)
• superficial skin nodules are a separate diagnostic entity

• inflammation of the subcutaneous tissue
• diagnosis can be confusing as many clinically look similar with features of:
  • deep induration
  • swelling of skin
  • erythema, warmth, tenderness
  • possible ulceration of overlying skin
• any diagnostic biopsy needs to include the subcutaneous tissue via either:
  • incisional biopsy
  • double punch biopsy technique (2nd punch is in same spot and provides access to subcutaneous layer)

• lupus profundus
• pancreatic
• alpha-1 antitrypsin deficiency
• cold panniculitis
• infection induced

• erythema nodosum (ant. shins esp.)
• erythema induratum
• esp. post. lower legs and may ulcerate
• occas. assoc with tuberculosis (TB) or as reaction to drugs or infections
• usually has septal vasculitis and is of a lobular pattern
• dermatomyositis
• lipodermaosclerosis (mainly medial, just above ankles)
• traumatic panniculitis
• subcutaneous panniculitis like T cell lymphoma