Cutaneous Markers of Systemic Disease
The skin is often the first organ to provide visible evidence of underlying systemic pathology. Recognizing these associations is vital for clinical diagnosis.
Systemic Associations Table
| Dermatological Finding | Systemic Association |
|---|---|
| Acanthosis Nigricans | Diabetes (insulin resistance) or GI malignancy. |
| Erythema Nodosum | Sarcoidosis, IBD, or Streptococcal infection. |
| Dermatitis Herpetiformis | Celiac disease (gluten-sensitive enteropathy). |
| Pyoderma Gangrenosum | Inflammatory Bowel Disease (IBD) or Rheumatoid Arthritis. |
Autoimmune & Endocrine Indicators
- Dermatomyositis: Look for Gottron papules (knuckles), heliotrope rash (eyelids), and the shawl sign. High risk for paraneoplastic disease.
- Lupus Erythematosus (SLE): Malar “butterfly” rash, discoid lesions, and photosensitivity.
- Hyperthyroidism: Pretibial myxedema (thickening of the skin over the shins).
High-Yield Exam Pearl:
- Pyoderma Gangrenosum: A classic “pathergy” lesion—it worsens with minor trauma or surgical debridement. Manage with systemic immunosuppressants, not surgery.
- Dermatitis Herpetiformis: Extremely pruritic vesicles on elbows and knees. Pathologically shows microabscesses of neutrophils at the dermal papillae.