Adnexal tumours of the skin
- Lesion
Tumours of hair follicles and sweat or oil glands are usually benign. A few point to inherited syndromes that also cause internal cancers.
What it is
Adnexal tumours differentiate toward hair follicle, sebaceous gland, or apocrine and eccrine sweat glands. Most are benign, slow-growing papules or nodules on the head and neck, and malignant versions are rare. Their importance lies in the syndromes they mark: multiple cylindromas and trichoepitheliomas in CYLD cutaneous syndrome, sebaceous tumours in Muir-Torre (a Lynch variant), trichilemmomas in Cowden syndrome.
Structure
- Cylindroma: dermal islands of small basaloid cells with peripheral palisading, surrounded and penetrated by hyaline basement membrane material.
- Sebaceous adenoma: lobules with more than half mature vacuolated sebocytes.
- Pilomatricoma: basaloid cells turning into eosinophilic anucleate ghost cells, calcification, giant cells.
Adnexal tumours and the syndromes they flag
| Tumour | Differentiation | Syndrome | Gene |
|---|---|---|---|
| Cylindroma, spiradenoma | Apocrine | CYLD cutaneous syndrome (Brooke-Spiegler) | CYLD |
| Trichoepithelioma (multiple) | Hair follicle | CYLD cutaneous syndrome | CYLD |
| Sebaceous adenoma or carcinoma | Sebaceous | Muir-Torre syndrome | Mismatch repair genes |
| Trichilemmoma (multiple) | Outer root sheath | Cowden syndrome | PTEN |
| Fibrofolliculoma | Hair follicle mantle | Birt-Hogg-Dubé syndrome | FLCN |
| Pilomatricoma | Hair matrix | Sporadic; myotonic dystrophy when multiple | CTNNB1 |
Clinical notes
- A sebaceous neoplasm prompts mismatch-repair immunostaining and a search for Lynch syndrome.
- Malignant adnexal tumours (sebaceous carcinoma of the eyelid, porocarcinoma) are rare but can metastasise.
Test yourself
Think of the answer, then tap the question to see it.
Which syndrome links sebaceous tumours of the skin with colon cancer?
Muir-Torre syndrome, a variant of Lynch syndrome caused by mismatch repair gene defects.
What is a turban tumour?
Many confluent cylindromas covering the scalp, typical of CYLD cutaneous syndrome.
What are ghost cells?
Anucleate eosinophilic keratinised cells characteristic of pilomatricoma.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: CYLD cutaneous syndrome (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.