Cutaneous Manifestations of Systemic Diseases

CTDs & Vasculitides - Immune Skin Wars

• Systemic Lupus Erythematosus (SLE)
  • Malar (butterfly) rash: Spares nasolabial folds.
  • Discoid rash: Erythematous, scaling plaques, follicular plugging, atrophy.
  • Photosensitivity, oral ulcers, alopecia.
  • Raynaud's phenomenon.
• Dermatomyositis
  • Heliotrope rash: Violaceous periorbital edema.
  • Gottron's papules: Violaceous papules on extensor surfaces of joints (MCP, PIP, DIP).
  • Shawl sign, V-sign: Poikiloderma on sun-exposed areas.
  • Mechanic's hands: Hyperkeratosis, fissuring of palms/fingers.
• Scleroderma (Systemic Sclerosis)
  • Limited (CREST): Calcinosis, Raynaud's, Esophageal dysmotility, Sclerodactyly, Telangiectasias.
  • Diffuse: Widespread skin thickening, early visceral involvement.
  • Salt-and-pepper hypopigmentation/hyperpigmentation.
• Vasculitides
  • Palpable purpura: Non-blanching, raised lesions (esp. lower limbs).
  • Livedo reticularis, ulcers, digital necrosis.
  • Henoch-Schönlein Purpura (IgA vasculitis): Palpable purpura, arthritis, abdominal pain, renal involvement.

⭐ Anti-Jo-1 antibodies are strongly associated with interstitial lung disease in dermatomyositis, often presenting with mechanic's hands.

📌 CREST for limited scleroderma features helps recall key manifestations immediately!

Endocrine & Metabolic - Sugar, Spice & Skin Vice

• Diabetes Mellitus (DM):
  • Necrobiosis lipoidica diabeticorum (NLD): Pretibial, waxy, yellow-brown plaques.
  • Diabetic dermopathy: Atrophic hyperpigmented "shin spots".
  • Acanthosis nigricans: Velvety hyperpigmentation (axillae, neck); sign of insulin resistance.
  • Eruptive xanthomas: Sudden yellow papules (↑ triglycerides).
• Thyroid Disorders:
  • Hypothyroidism: Myxedema (non-pitting), dry coarse skin, madarosis (📌 Hertoghe's sign: lateral eyebrow loss).
  • Hyperthyroidism (Graves'): Pretibial myxedema (indurated plaques, peau d'orange), thyroid acropachy.
• Porphyria Cutanea Tarda (PCT):
  • Most common porphyria; photosensitivity, vesicles/bullae, skin fragility, facial hypertrichosis.

  ⭐ PCT is frequently triggered by alcohol, estrogens, Hepatitis C, or hemochromatosis.

• Xanthomas (Lipid Disorders):
  • Eruptive (↑TG), Tuberous & Tendinous (↑Cholesterol, e.g., Achilles).
  • Xanthelasma palpebrarum: Eyelid plaques.
• Cushing's Syndrome: Purple striae, skin atrophy, moon facies, buffalo hump.
• Addison's Disease: Diffuse hyperpigmentation (sun-exposed, buccal mucosa, palmar creases).

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Paraneoplastic Syndromes - Cancer's Skin Clues

• Acanthosis Nigricans (Malignant type): Velvety, hyperpigmented plaques, often in flexures. Assoc: GI adenocarcinoma (esp. stomach).
• Dermatomyositis: Heliotrope rash, Gottron's papules. Assoc: Ovarian, lung, GI cancers.
• Leser-Trélat Sign: Sudden onset/↑ in seborrheic keratoses. Assoc: GI (stomach, colon), lymphoma.
• Necrolytic Migratory Erythema: Annular, erosive lesions. Assoc: Glucagonoma.
• Sweet's Syndrome (Acute Febrile Neutrophilic Dermatosis): Tender, erythematous plaques/nodules, fever. Assoc: AML.
• Erythema Gyratum Repens:

GI & Renal Issues - Gut & Kidney Skin News

• Inflammatory Bowel Disease (IBD):
  • Pyoderma gangrenosum (painful ulcers, violaceous undermined borders)
  • Erythema nodosum (tender red nodules, typically on shins)
  • Oral aphthous ulcers
• Celiac Disease:
  • Dermatitis herpetiformis (intensely pruritic vesicles on extensor surfaces; IgA deposits)
• Peutz-Jeghers Syndrome:
  • Mucocutaneous lentigines (lips, oral mucosa, digits)
• Chronic Kidney Disease (CKD):
  • Uremic pruritus (most common symptom)
  • Xerosis, Calciphylaxis (painful necrosis)
  • Nephrogenic Systemic Fibrosis (post-gadolinium)
  • Half-and-half nails (Lindsay's nails)
• Acrodermatitis Enteropathica:
  • Zinc deficiency; periorificial & acral dermatitis, alopecia. 📌 ADE = Acral, Diarrhea, Eczema (periorificial).

⭐ Dermatitis herpetiformis is strongly associated with celiac disease; skin biopsy shows granular IgA deposits at the dermal-epidermal junction.

High‑Yield Points - ⚡ Biggest Takeaways

• Acanthosis nigricans: Velvety plaques; linked to insulin resistance (diabetes) & GI malignancy.
• Dermatomyositis: Heliotrope rash, Gottron's papules; signals underlying malignancy.
• Erythema nodosum: Tender shin nodules; seen with infections (TB), sarcoidosis, IBD.
• Pyoderma gangrenosum: Painful ulcers, violaceous borders; associated with IBD, arthritis.
• Necrobiosis lipoidica: Atrophic shin plaques; classic for diabetes mellitus.
• Porphyria cutanea tarda: Sun-induced blisters, fragility; linked to liver disease (HCV).
• SLE: Malar rash, photosensitivity, discoid lesions are key cutaneous signs.