Clear cell lacanthoma D23.L

Degos 1962

0.5 to 2 cm in size, oval, skin-coloured to pale red, rarely light brown, slow-growing, dome-shaped papule/nodules with usually only slightly scaly surface, which is sometimes colarette-like at the edges. Rarely multiple occurrences. Clinically, the "inconspicuous" neoplasms are usually classified as seborrhoeic keratoses.

Broad, acanthotic epithelial band with sharply defined area of large epithelia with water clear, PAS-positive, non-diastase resistant cytoplasm and a small, centrally located nucleus. Above the light-cellular zone a severe parakeratosis is usually visible. The dermis shows spindly lymphoid cell infiltrates. No increase of the mitosis rate. The epithelial ligament regularly contains sparsely distributed neutrophil granulocytes, which are rarely compressed to subcorneal microabscesses.

Some authors distinguish 4 histological types in clear cell acanthoma:

• Psoriasiform type
• Solid-acanthotic type
• Reticular type
• Exophytic type

Clinical:

• Verruca seborrhoica: Clinically indistinguishable; usually more pigmented.
• Porom ekkrines: Histological incidental diagnosis
• Stukkokeratosis: flat, usually wart-like neoplasm with powdery surface

Histologic:

• Verruca seborrhoica: No clear cell component
• eccrine poroma: proliferation of cuboidal CEA-positive cells, tubular structures
• Tricholemmoma: Low-lying sharply demarcated nodule, trichilemmal keratinization
• clear cell hidradenoma: extension into the dermis, no involvement of neutrophilic granulocytes

1. Blum A et al (2001) The dermatoscopic pattern of clear-cell acanthoma resembles psoriasis vulgaris. Dermatology 203: 50-52
2. Bugatti L et al (2003) Psoriasis-like dermoscopic pattern of clear cell acanthoma. J Eur Acad Dermatol Venereol 17: 452-455
3. Degos R et al (1962) Tumeur épidermique d'aspect particulier: acanthome à cellules claires. Dermatologica 129: 361-372
4. Fandrey K et al (1995) Multiple clear cell lacanthomas. Dermatologist 46: 865-868
5. Finch TM et al (2000) Clear cell acanthoma developing on a psoriatic plaque: further evidence for an inflammatory aetiology. Br J Dermatol 142: 842-845