Synopsis
Recognise cutaneous clues to internal disease, separate common benign findings from time-critical syndromes, and investigate the whole clinical pattern rather than a skin sign in isolation.
- A skin sign is a clue, not a diagnosis: integrate onset, symptoms, medicines, physiology, mucosae, nails, nodes and organ-specific findings.
- Non-blanching petechiae or purpura in an unwell patient requires urgent assessment for infection, thrombocytopenia, coagulopathy and vasculitis.
- Generalised pigmentation involving creases, scars or oral mucosa with weakness, weight loss and postural dizziness supports primary adrenal insufficiency.
- Acanthosis nigricans commonly tracks insulin resistance; abrupt extensive disease with weight loss or mucosal involvement needs broader assessment.
- For Skin signs of systemic disease, describe what is seen before assigning a diagnosis, and record site, extent, symptoms, duration and change over time.
- A technically adequate result in Skin signs of systemic disease can still be misleading when the wrong lesion, site, preparation or clinical question was selected.
Key red flags
Fever, hypotension, altered mental state, breathlessness, rapidly evolving purpura, mucosal injury, unexplained weight loss or acute kidney findings make a systemic skin sign urgent.
Rapidly evolving non-blanching lesions plus fever, hypotension or altered consciousness can indicate invasive infection or severe haematological disease.
Branching angulated purpura, livedoid change and pain out of proportion suggest vessel occlusion or vasculopathy with possible organ threat.
Investigation priorities
Identify sepsis, shock, respiratory failure or adrenal crisis before diagnostic refinement.
Management branches
The patient is stable and the result will alter diagnosis, referral or follow-up.
- Define the question for Skin signs of systemic disease, explain the process and obtain valid consent before exposing, touching, photographing or sampling skin.
- Choose representative anatomy, optimise lighting or specimen technique, and document site, morphology, symptoms and relevant previous treatment. Apply that step specifically within the skin signs of systemic disease assessment and its recorded clinical context.
- Interpret the result beside the full clinical pattern, communicate uncertainty and arrange ownership of results and safety-netting. Apply that step specifically within the skin signs of systemic disease assessment and its recorded clinical context.