Are these nodules likely to regress spontaneously?

Case 4:
Several weeks earlier these slightly tender nodules erupted on the arms and legs of a 75-year-old woman with extensive sun damage.

What is your clinical impression?

A. Warts.
B. Actinic keratoses.
C. Keratoacanthomas.
D. Squamous cell carcinomas.
E. Folliculitis.

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It would unusual for multiple warts, squamous cell carcinomas, or actinic keratoses to suddenly appear unless the patient was immunocompromised.

The nodules are not typical of folliculitis. A skin biopsy revealed these lesions to be the keratoacanthoma type of squamous cell carcinoma.

How would you treat them?

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A keratoacanthoma, C, is a variant of squamous cell carcinoma that often undergoes spontaneous involution. However, eruptive keratoacanthomas of Grzybowski is defined as a generalized distribution of multiple keratoacanthomas that typically do not involute.¹

The primary treatment of keratoacanthoma is surgery. Medical therapy is reserved for patients with comorbidities that preclude surgery and for those who have multiple lesions or lesions that are not amenable to surgical intervention because of size or location.

Consider systemic retinoids, such as isotretinoin, for patients with numerous lesions.¹ Intralesional methotrexate, 5-fluorouracil, bleomycin, and corticosteroids have been effective in patients who are poor surgical candidates or who have lesions that preclude surgery because of size or location.^2-5 There are also anecdotal reports of the successful use of topical imiquimod and 5-fluorouracil^.6,7

Most of the literature supporting medical therapy for keratoacanthoma consists of case reports. Thus, close follow-up of patients receiving such therapy is warranted because surgery will be indicated for those lesions that do not completely respond.

References:

1. Vandergriff T, Nakamura K, High WA. Generalized eruptive keratoacanthomas of Grzybowski treated with isotretinoin. J Drugs Dermatol. 2008;7:1069-1071.
2. Annest NM, VanBeek MJ, Arpey CJ, Whitaker DC. Intralesional methotrexate treatment for keratoacanthoma tumors: a retrospective study and review of the literature. J Am Acad Dermatol. 2007;56:989-993.
3.. Eubanks SW, Gentry RH, Patterson JW, May DL. Treatment of multiple keratoacanthomas with intralesional fluorouracil. J Am Acad Dermatol. 1982;7: 126-129.
4.Sayama S, Tagami H. Treatment of keratoacanthoma with intralesional bleomycin. Br J Dermatol. 1983;109:449-452.
5. Sanders S, Busam KJ, Halpern AC, Nehal KS. Intralesional corticosteroid treatment of multiple eruptive keratoacanthomas: case report and review of a controversial therapy. Dermatol Surg. 2002;28:954-958.
6.. Dendorfer M, Oppel T, Wollenberg A, Prinz JC. Topical treatment with imiquimod may induce regression of facial keratoacanthoma. Eur J Dermatol. 2003;13:80-82.
7. Gray RJ, Meland NB. Topical 5-fluorouracil as primary therapy for keratoacanthoma. Ann Plast Surg. 2000;44:82-85.