Keratoacanthoma Differential Diagnoses

Updated: Feb 24, 2020
  • Author: Tsu-Yi Chuang, MD, MPH, FAAD; Chief Editor: William D James, MD  more...
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Diagnostic Considerations

See the list below:

  • Eruptive keratoacanthoma (KA) of Grzybowski: This is characterized by a generalized eruption of numerous dome-shaped, skin-colored papules from 2-7 mm in diameter. Multiple larger typical keratoacanthomas may also appear. The eruption is usually generalized, but spares the palms and soles. Severe pruritus may be a feature. The papular lesions typically do not involute.

  • Multiple Ferguson-Smith keratoacanthoma: This is a rare autosomal dominant self-healing type of keratoacanthoma, with lesions arising in early adulthood.

  • Keratoacanthoma centrifugum margination: This variant is characterized by progressive peripheral growth and eventual size often 5-30 cm.

  • Muir-Torre syndrome: Keratoacanthoma may be a component of Muir-Torre syndrome, which is a cancer-associated genodermatosis with multiple sebaceous neoplasms (adenomas, epitheliomas, carcinomas), keratoacanthomas, and gastrointestinal malignancies (most commonly colon), although other carcinomas have been reported (genitourinary, pulmonary, endometrial). When Muir-Torre syndrome is diagnosed, an age-appropriate cancer screening workup is indicated. An approximately equal number of internal malignancies are diagnosed before and after the cutaneous neoplasm. These internal malignancies tend to be low grade, but early diagnosis is important. Colonoscopy, rather than flexible sigmoidoscopy, is recommended, since the colon cancer frequently is found in the right ascending colon, proximal to the hepatic flexure.

Differential Diagnoses