Sweat Gland Tumours
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Direct answer
Eccrine and apocrine lineages generate a long list of cutaneous adnexal tumours whose names intimidate but whose logic is orderly: know the lineage, the classic site and the one discriminating histological image for each. Eccrine derivatives include syringoma of the lower eyelids, eccrine poroma of the palm and sole, and eccrine spiradenoma — a classically painful blue-red dermal nodule. Apocrine derivatives include cylindroma of the scalp, which accumulates into the "turban tumour" of Brooke-Spiegler syndrome, and hidradenoma papilliferum of the vulva. Malignant counterparts are rare but real, and the gene to carry into the examination hall is CYLD, the tumour suppressor whose germline mutation unites cylindroma, spiradenoma and trichoepithelioma in one family syndrome.
What you must remember
- Eccrine line, commonest first: syringoma — small firm papules of the lower eyelids and cheeks in adolescent women; histology shows comma-shaped or "tadpole" eccrine ducts in a fibrous stroma.
- Eccrine poroma: a red, moist, sometimes bleeding nodule on the palm or sole (acral skin is eccrine territory — the site itself is the clue), histologically connected to the epidermis with poroid cells; porocarcinoma is its rare malignant counterpart.
- Eccrine spiradenoma: a solitary, dome-shaped, blue-red dermal nodule that is markedly tender — one of the classically painful skin tumours alongside glomus tumour, piloleiomyoma, angiolipoma and traumatic neuroma; two populations of basaloid cells arranged in rosettes with hyaline stroma.
- Chondroid syringoma: the cutaneous mixed tumour of the head and neck, combining epithelial structures with a chondroid (cartilage-like) stroma — the skin's pleomorphic adenoma analogue.
- Apocrine line: cylindroma — scalp nodule(s) of pink-brown colour; histology of mosaic "jigsaw puzzle" cylinders of basaloid cells with hyaline sheaths; multiple lesions form the turban tumour.
- Brooke-Spiegler syndrome: autosomal dominant CYLD mutation (chromosome 16) uniting cylindromas, spiradenomas and trichoepitheliomas; malignant transformation of cylindroma or spiradenoma is uncommon but reported.
- Hidradenoma papilliferum: a benign apocrine tumour, typically a small nodule on the vulva (occasionally perianal or nipple) of adult women, with characteristic papillary infoldings into a cystic space.
- Practical rule: painful dermal nodule, no obvious inflammation — think spiradenoma (or glomus); slow scalp nodule — think cylindroma; eyelid papules in a young woman — syringoma.
Mapping by site and symptom
Organise the family the way clinics present it. A young woman with dozens of 1-to-2-millimetre papules clustered on both lower eyelids has syringoma — the distribution does the diagnosis before the biopsy confirms tadpole ducts. A middle-aged man with a 1-centimetre, exquisitely tender nodule on the forearm flexor surface, present for years and unchanged but sore, generates the painful-tumour differential: spiradenoma wins on dermoscopy (blue-red, well-circumscribed) and on histology (two basaloid cell populations, hyaline globules); excision is curative and the relief is immediate. A 50-year-old woman whose scalp carries multiple lobulated nodules coalescing over the vertex like a turban has cylinomatosis — and the next question is the family tree, because Brooke-Spiegler syndrome marches through generations with CYLD; genetic counselling and planned excision or laser ablation of disfiguring lesions follow.
Acral skin completes the map: a friable, red, oozing nodule on the heel, misread as a pyogenic granuloma or amelanotic melanoma, biopsies as eccrine poroma; the wrong assumption is harmless, but a porocarcinoma in the same site behaves aggressively, so histological confirmation of any persistent acral "granuloma" is the discipline.
Where the exam sets its traps
The painful-tumour list is the trap that keeps giving: candidates forget spiradenoma and leap to glomus tumour (subungual, ice-pick pain) or leiomyoma (cold-induced pain); spiradenoma earns its place by being the tender blue-red dermal nodule of young adults. Second, the tumour-suppressor gene is misassigned — CYLD belongs to cylindroma and Brooke-Spiegler syndrome, not to the syringoma family, and CYLD-associated tumours can hybridise (spiradenocylindroma), which is itself a recognised report line. Third, do not overcall malignancy: multiple scalp cylindromas look alarming but are benign until growth acceleration, ulceration or atypical histology says otherwise — and then management changes to wide excision with margin control.
Frequently asked questions
Which sweat gland tumour is characteristically painful?
Eccrine spiradenoma — a tender, blue-red dermal nodule with two basaloid cell populations on histology, excision being curative.
What is a turban tumour?
Multiple cylindromas of the scalp coalescing into a large, lobulated mass, classically in Brooke-Spiegler syndrome with CYLD mutation.
Which gene and inheritance pattern underlie Brooke-Spiegler syndrome?
Germline mutation of the CYLD tumour suppressor on chromosome 16, autosomal dominant, uniting cylindromas, spiradenomas and trichoepitheliomas.
Where does eccrine poroma occur and what does it mimic?
On acral skin, especially the palm and sole, where it mimics pyogenic granuloma or amelanotic melanoma as a red, friable nodule.
What is hidradenoma papilliferum and where is it found?
A benign apocrine tumour with papillary infoldings, presenting as a small nodule on the vulva of adult women.