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Cutaneous signs of internal malignancy
Some skin diseases are "messengers" of internal cancer — they appear before or with it and disappear when it is treated; recognising them early leads to early diagnosis of the tumour.
Why it matters in the exam
Exam stems show classic signs: sudden widespread acanthosis nigricans in a thin older adult (gastric adenocarcinoma), the sudden appearance of dozens of seborrhoeic keratoses (Leser-Trélat sign), dermatomyositis in an adult (ovarian, lung, gastric and pancreatic cancer), necrolytic migratory erythema around the mouth and groin (glucagonoma), migratory thrombophlebitis (Trousseau sign in pancreatic cancer), "wood-grain" erythema gyratum repens (lung cancer), and Bazex paraneoplastic acrokeratosis (pharyngeal and oesophageal cancer). The question tests matching the sign to the tumour and the right work-up. Remember that in dermatomyositis TIF1-gamma and NXP2 antibodies raise the cancer risk, and that screening follows age and sex, including CT of the chest, abdomen and pelvis and a gynaecological examination in women. The key understanding is that a paraneoplastic sign heals when the tumour is treated and returns when the tumour returns. With every such sign, ask about weight loss, night sweats and change in bowel habit.
Key points
- Paraneoplastic skin signs appear before or together with the cancer and disappear with its treatment.
- Malignant acanthosis nigricans is linked to gastric adenocarcinoma, and the Leser-Trélat sign to a sudden eruption of seborrhoeic keratoses.
- Dermatomyositis in an adult is linked to ovarian, lung, gastric and pancreatic cancer, especially with TIF1-gamma antibodies.
- Necrolytic migratory erythema around the mouth and groin is a sign of glucagonoma.
- Erythema gyratum repens is linked to lung cancer, and Bazex acrokeratosis to pharyngeal and oesophageal cancer.
Summary table
| Skin sign | Appearance | Associated malignancy | Note |
|---|---|---|---|
| Malignant acanthosis nigricans | Dark velvety thickening in the axillae and neck, sudden onset, "tripe palms" | Gastric adenocarcinoma | Unlike the common form linked to insulin resistance |
| Leser-Trélat sign | Sudden appearance of many seborrhoeic keratoses | Gastrointestinal adenocarcinoma | Often together with malignant acanthosis |
| Dermatomyositis | Heliotrope rash, Gottron papules, rash on the shoulders and chest, proximal weakness | Ovary, lung, stomach, pancreas, nasopharynx | TIF1-gamma antibodies raise the risk; cancer screening |
| Necrolytic migratory erythema | Migrating peeling plaques around the mouth, groin and folds, diabetes and weight loss | Glucagonoma | Glucagon level; octreotide |
| Erythema gyratum repens and Bazex acrokeratosis | Gyratum: migrating concentric wood-grain bands; Bazex: violaceous scale on the nose, ears and fingers | Gyratum: lung cancer; Bazex: pharyngeal and oesophageal cancer | Disappear with tumour treatment |
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Sources
- Fitzpatrick's Dermatology, 9th edition (2019) — Cutaneous manifestations of internal malignant disease
- EULAR/ACR classification criteria for idiopathic inflammatory myopathies, 2017 — Dermatomyositis
- British Association of Dermatologists guidance on paraneoplastic dermatoses, 2020 — Investigation
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.