Eruptive squamous atypia (also known as eruptive keratoacanthoma): Definition of the disease entity and successful management via intralesional 5-fluorouracil.

BACKGROUND

Eruptive squamous atypia (ESA), which is an idiopathic, sometimes koebnerizing, proliferation of atypical but well-differentiated keratinocytes (also termed eruptive keratoacanthoma), is often misdiagnosed as cancer and managed by excisional surgery, provoking further koebnerization. A clear definition of this phenomenon and treatment outcome data are lacking.

OBJECTIVE

To define ESA and evaluate efficacy of intralesional (IL) 5-fluorouracil (5-FU) treatment.

METHODS

A retrospective cohort study examined patients with ESA that arose spontaneously or within a recent surgical scar and was treated with IL 5-FU at a tertiary academic center between January 2008 and December 2016. Complete clearance, partial clearance, and number of surgical excisions performed were tabulated.

RESULTS

Of 30 patients with 136 ESA lesions, 20 (67%) had resolution of ESA with IL 5-FU monotherapy. In all, 10 patients (33%) required additional therapy (topical 5-FU, steroids, cryotherapy, or acitretin). No IL 5-FU-treated ESA lesions required surgical excision. The number of excisional procedures decreased significantly (P = .006), with 27 patients (90%) needing fewer excisions 12 months after versus 12 months before initiation of IL 5-FU therapy. Dyspigmentation was the only adverse event.

LIMITATIONS: Limitations include retrospective analysis and use of data from a single institution.

CONCLUSION

With close clinical monitoring, IL 5-FU can be used to successfully treat ESA.