Keratoakanthoma (overview) D23.-

Authors: Prof. Dr. med. Peter Altmeyer, Pia Nagel

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Last updated on: 29.10.2020

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Epitheliomas multiple self-healing of the skin; idiopathic cutaneous pseudoepitheliomatous hyperplasia; Keratoacanthoma; Keratoakanthom solitäres; Molluscum sebaceum; Molluscum sebaceum and pseudocarcinomatosum; self-healing spiny cell carcinoma; Spiny cell carcinoma self-healing

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Hutchinson, 1889

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Initially fast-growing (according to typical medical history usually a few weeks), solitary, rarely occurring in majority, epithelial tumour, 1.0 to a maximum of 3.0 cm in size, which develops from the hair follicle or from the surface epithelium of the skin (rarely the mucous membrane), initially grows infiltratively and may have a spontaneous regression tendency after weeks to months with expulsion of a central corneal plug (the growth behaviour is interpreted as an analogy to the hair cycle).

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Besides the classical type of KA, different clinical variants have been described: in particular the plate-like type, the destructive subungual type, the aggregated KA, multiple, destructively growing KA, the keratoacanthoma marginatum centrifugum (type Miedzinski-Kozakiewicz) and the giant keratoacanthoma.

All variants show an identical histological picture and differ only in their macro-morphological pattern, their localisation (e.g. in subungual KA) and their growth behaviour (destructive variants).

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Unsolved. Frequently occurring after actinic noxae (predominant occurrence in light-exposed areas), after mechanical trauma, contact with chemical carcinogens, in immunosuppression as well as paraneoplastic in neoplasia of internal organs (especially the intestinal tract).

Genetic factor: occurrence of multiple CA in genetic syndromes (see classification).

The pathogenetic significance of HPV (HPV 25), especially in multiple CA, is still unclear.

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Manifestation rarely before the 20th LJ, more frequent in men from the age of 55 (frequency peaks between 50th-79th LJ). More frequent occurrence is observed in immunocompromised persons. Men are affected about twice as often as women.

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Light-exposed areas of fair-skinned persons, especially face, also back of the hand. Palms of hands and soles of feet remain free, as do mucous membranes.

Clinical features
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The classical keratoacanthoma described here impresses as a solitary, 0.5 cm to a maximum of 3.0 cm (literature: in individual cases up to 9.0 cm!) large, spherically bulging, hard, red or red-brown, centrally dented, painless nodule (or nodule), the surface of which is pervaded by telangiectasia.

A typical feature is a wall-like raised rim which encloses the central, grey-yellow keratotic plug in a lip shape.

The keratoacanthoma is well movable on its base.

A three-phase clinical course is typically observed:

  1. stage of proliferation (duration about 2-6 weeks) with rapid growth (period of clinical presentation)
  2. stage of maturation (static phase; duration indefinite)
  3. stage of regression (this stage is controversial and should not be waited for).

Multiple keratoakanthomas are described as 0.1-1.2 cm large, firm, skin-coloured to reddish papules and nodes.

The giant keratoakanthoma (also called Keroakanthoma giganteum) shows an unusual, oversized (up to 10 cm) size growth with typical clinical and histological morphology.

Keratoacanthoma marginatum centrifugum, an unusual variant of the giant keratoacanthoma, is characterized by a plate-like appearance with no tendency to regression in the marginal area of the tumor.

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  • Histological differentiation from squamous cell carcinoma in punch biopsies or partial excidates is not possible. In this respect, the histological diagnosis of CA can only be made if it presents itself in its typical histomorphological form.
  • In this case a central horn plug is visible, which is surrounded by broad epidermal tumor proliferates in a lip shape. The tumor proliferates show infiltrating and destructive growth. The surrounding connective tissue is clearly fibrosed and infiltrated by round cells. The basal keratinocytes are clearly enlarged and show a strongly eosinophilic cytoplasm. Especially in the proliferation stage the basal tumor parts are clearly cell- and nuclear polymorphic with single cell dyskeratoses as well as numerous pathological mitoses. In addition, small horny beads with concentrically layered keratinocytes. The number of mitoses varies and is clearly increased in young CA, in older ones only moderately. In older CA an increasing inflammatory component is found in the tumor parenchyma with microabscesses of eosinophilic and neutrophilic leukocytes as well as isolated giant cells of the foreign body type.

Differential diagnosis
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Radiation therapy
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X-ray soft tissue irradiation: Not very common, only if a surgical intervention is out of the question due to the size of the tumour, the age of the patient or due to unfavourable localisation. Dosage: 4-5 times 5 Gy (2 fractions per week). Keratoacanthomas regress very slowly over a period of several weeks.

Internal therapy
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In multiple keratoacanthomas most therapy approaches prove to be unsatisfactory. Trials with acitretin (neotigason) 0.5-1.0 mg/kg bw/day, isotretinoin and methotrexate are described.

Operative therapie
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  • Excision is the treatment of choice. Safety distance to the side and to a depth of 2-3 mm.
  • Alternatively: curettage and immediate application of a 5-fluorouracil cream(e.g. Efudix). Repeat Efudix treatment 3-4 times in 2-day intervals.
  • Alternatively, curettage followed by immediate cryosurgery (2 cycles, closed procedure) or curettage and cauterization of the base.

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Cheap. Spontaneous regression is possible. Transition to squamous cell carcinoma is also possible, metastasis has been reported in individual cases.

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The keratoacanthoma cannot be distinguished clinically or histologically from a spinocellular squamous cell carcinoma. It is therefore not recommended to wait for a "self-healing" of the tumor.

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  1. Boateng B et al (1995) Multiple keratoacanthomas (Witten-Zak type) in prurigo simplex subacuta. dermatologist 46: 114-117
  2. Chu DH et al (2003) Generalized eruptive keratoacanthoma of Grzybowski. J Drugs Dermatol 2: 318-319
  3. Consigli JE et al (2000) Generalized eruptive keratoacanthoma (Grzybowski variant). Br J Dermatol 142: 800-803
  4. Hsu S et al (2003) Reactive multiple keratoacanthoma in a patient with chronic renal insufficiency. Br J Dermatol 148: 1270-1271
  5. Hutchinson J (1889) The crateriform ulcer of the face, a form of acute epithelial cancer. Trans Pathol Soc London 40: 275-281
  6. Jasnoch V et al (1995) The rare variants of keratoacanthomas. dermatologist 46: 244-9
  7. Kato N et al (2003) Ferguson Smith type multiple keratoacanthomas and a keratoacanthoma centrifugum marginatum in a woman from Japan. J Am Acad Dermatol 49: 741-746
  8. Laaff H et al. (1992) Eruptive keratoacathomas type Grzybowski and ectropion. A therapeutic problem. Dermatologist 43: 143-147
  9. Norgauer J et al (2003) Human papillomavirus and Grzybowski's generalized eruptive keratoacanthoma. J Am Acad Dermatol 49: 771-772
  10. Peris K et al (2003) Successful treatment of keratoacanthoma and actinic keratoses with imiquimod 5% cream. Eur J Dermatol 13: 413-414
  11. Remling R et al (2000) Intralesional methotrexate injection: an effective time and cost saving therapy alternative in keratoacanthomas that are difficult to treat surgically. dermatologist 51: 612-614
  12. Rinker MH et al (2001) Histologic variants of squamous cell carcinoma of the skin. Cancer Control 8: 354-363
  13. Schwartz RA et al (2002) Generalized eruptive keratoacanthoma of Grzybowski: follow-up of the original description and 50-year retrospect. Dermatology 205: 348-352
  14. Sanchez Yus E et al (2000) Solitary keratoacanthoma: a self-healing proliferation that frequently becomes malignant. At J Dermatopathol 22: 305-310


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Last updated on: 29.10.2020