Connective Tissue Disorders of the Skin

Connective Tissue Disorders of the Skin

Connective Tissue Disorders of the Skin

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Overview of CTDs - Skin's Support Woes

  • Diverse group affecting skin's connective tissues (collagen, elastin, ground substance). Lead to compromised structural integrity, support, and altered skin appearance.
TypePathogenesisCommon Skin Manifestations / Examples
AutoimmuneImmune-mediated damage to connective tissuePhotosensitivity, rash (SLE, DM); Skin thickening (Scleroderma)
HeritableGenetic mutations affecting protein structure/fxnSkin hyperextensibility, fragility (EDS); Striae, ectopia lentis (Marfan)

⭐ Many autoimmune CTDs show interface dermatitis histologically, a key pattern to recognize.

Lupus Erythematosus - Butterfly's Sting

Autoimmune CTD; key skin manifestations:

TypeLesionsSystemicAntibodies
DLEErythematous plaques, adherent scale, follicular plugging, atrophy, scarringRareOften ANA -ve
SCLEPapulosquamous/annular, photosensitive, non-scarring~50% mild SLEAnti-Ro, Anti-La
SLEMalar rash, photosensitivity, oral ulcers, discoid lesions (can occur)CommonANA, Anti-dsDNA

Malar rash in lupus erythematosus

⭐ Direct immunofluorescence (DIF) of lesional skin showing a 'lupus band' (granular deposits of IgG, IgM, C3 at DEJ) is highly characteristic of LE.

Scleroderma Spectrum - Hardening Truths

  • Systemic Sclerosis (SSc): Autoimmune disorder; progressive skin thickening & visceral organ fibrosis.
FeatureLimited Cutaneous SSc (lcSSc)Diffuse Cutaneous SSc (dcSSc)
Skin InvolvementFingers, hands, face/neck. Distal to elbows/knees. Slow progression.Widespread: trunk, proximal & distal limbs. Rapid progression.
📌 MnemonicCREST: Calcinosis, Raynaud's, Esophageal dysmotility, Sclerodactyly, Telangiectasias.-
Key AntibodiesAnti-Centromere (ACA)Anti-Scl-70 (topoisomerase I), Anti-RNA Polymerase III
Major Organ RiskPulmonary Arterial Hypertension (PAH)Interstitial Lung Disease (ILD), Scleroderma Renal Crisis

Anti-Scl-70 (topoisomerase I) antibodies are strongly associated with diffuse cutaneous systemic sclerosis and an increased risk of pulmonary fibrosis.

Dermatomyositis - Rash & Weakness

Autoimmune inflammatory myopathy; characteristic skin findings & proximal muscle weakness.

  • Key Skin Signs:
    • Heliotrope rash (eyelids)
    • Gottron's papules (knuckles)
    • Gottron's sign (extensor surfaces)
    • Shawl sign (shoulders/back), V-sign (neck/chest)
    • Mechanic's hands Gottron's papules on hand in dermatomyositis
  • Muscle: Symmetrical proximal weakness; ↑CK, aldolase.
  • Associations: Interstitial lung disease (ILD), calcinosis cutis.
  • Antibodies: Anti-Mi-2 (classic), Anti-Jo-1 (ILD, mechanic's hands).

⭐ Adult-onset dermatomyositis carries a 15-25% risk of underlying internal malignancy (ovarian, lung, GI), requiring screening.

Heritable CTD Snippets - Genetic Threads

  • Focus: Genetic defects primarily affecting collagen & elastin.
DisorderGene(s) / Protein DefectKey Skin Manifestations
Ehlers-Danlos (EDS)COL genes; CollagenSkin hyperextensibility, atrophic "cigarette paper" scars, easy bruising
Pseudoxanthoma (PXE)ABCC6; MRP6 proteinYellow papules ('plucked chicken skin') in flexures, lax skin
Marfan SyndromeFBN1; Fibrillin-1Striae atrophicae (esp. shoulders, buttocks, back), thin skin

Pseudoxanthoma elasticum (PXE), caused by ABCC6 gene mutations, classically presents with 'plucked chicken skin' appearance in flexural areas and may have serious cardiovascular and ocular (angioid streaks) complications.

High‑Yield Points - ⚡ Biggest Takeaways

  • Lupus Erythematosus: Interface dermatitis, liquefaction degeneration, thickened basement membrane (PAS+), positive Lupus Band Test.
  • Dermatomyositis: Heliotrope rash, Gottron's papules; interface changes; associated with internal malignancy.
  • Scleroderma: Homogenized collagen, loss of adnexa; Anti-Scl-70 (diffuse), Anti-centromere (CREST).
  • Morphea: Localized scleroderma with dermal sclerosis, no systemic features.
  • Ehlers-Danlos Syndrome: Defective collagen causing skin hyperextensibility, joint hypermobility.
  • Pseudoxanthoma Elasticum: Calcified elastic fibers; angioid streaks; ABCC6 mutation.

Practice Questions: Connective Tissue Disorders of the Skin

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A female patient of 26 years, presents with oral ulcers, photosensitivity and skin malar rash in face sparing the nasolabial folds of both side.

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Flashcards: Connective Tissue Disorders of the Skin

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Inflammation in _____-myositis is mediated by CD-4+ T cells

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Inflammation in _____-myositis is mediated by CD-4+ T cells

dermato

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