Keratoacanthoma developing in previous cryotherapy site for solar keratosis

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.

Pharmacokinetics of ingenol mebutate gel under maximum use conditions in large treatment areas

PURPOSE

Actinic keratoses (AKs) exist on a continuum with squamous cell carcinoma and can occur as sub-clinical and clinically visible lesions in cancerized fields on sun-damaged skin. Ingenol mebutate effectively treats AKs on areas up to 25 cm², but actinic keratosis can affect larger areas of skin. This trial evaluated systemic exposure and safety of ingenol mebutate gel on larger areas of skin under maximum use conditions.

METHODS

Phase I, multicenter, open-label, uncontrolled, non-randomized trial. Patients received ingenol mebutate gel for three consecutive days on approximately 250 cm² of sun-damaged skin on the full face (0.027%), the scalp (0.027%), or arm (0.06%).

RESULTS

Of 61 patients, 10 (face =8; arm =2) had ingenol mebutate in whole blood at subnanomolar levels (0.235-0.462 nM). The assayed metabolites were below the lower limit of quantification. Local skin responses increased during Days 1-4 and declined thereafter, approaching baseline by Day 16. Most adverse events were pain/pruritus of mild or moderate intensity.

CONCLUSIONS

Subnanomolar systemic exposure to ingenol mebutate was measured after application of the gel to approximately 250 cm² on the full face, scalp, or arm under maximum use conditions. No clinically relevant systemic adverse reactions were observed, and local skin responses were manageable.

CD1A-positive cells and HSP60 (HSPD1) levels in keratoacanthoma and squamous cell carcinoma

CD1a is involved in presentation to the immune system of lipid antigen derived from tumor cells with subsequent T cell activation. Hsp60 is a molecular chaperone implicated in carcinogenesis by, for instance, modulating the immune reaction against the tumor. We have previously postulated a synergism between CD1a and Hsp60 as a key factor in the activation of an effective antitumor immune response in squamous epithelia. Keratoacantomas (KAs) are benign tumors that however can transform into squamous cell carcinomas (SCCs), but the reasons for this malignization are unknown. In a previous study, we found that CD1a-positive cells are significantly more numerous in KA than in SCC. In this study, we analyzed a series of KAs and SCCs by immunohistochemistry for CD1a and Hsp60. Our results show that the levels of both are significantly lower in KA than in SCC and support the hypothesis that KA may evolve towards SCC if there is a failure of the local modulation of the antitumor immune response. The data also show that immunohistochemistry for CD1a and Hsp60 can be of help in differential diagnosis between KAs and well-differentiated forms of SCC.