Keratoacanthoma developing in prurigo nodularis treated with cryotherapy

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.

Keratoacanthomas arising in association with prurigo nodules in pruritic, actinically damaged skin

BACKGROUND

There is no known association between the development of keratoacanthomas and prurigo nodules.

OBJECTIVE

We report a case series of 7 patients with a long-standing history of actinic damage, pruritus, and prurigo nodularis who developed widespread keratoacanthomas within the same affected area.

METHODS

This was a retrospective case series assessing the clinical characteristics of patients with multiple keratoacanthomas arising in association with prurigo nodules.

RESULTS

All 7 patients were elderly Caucasian women (mean age 79 ± 3.7 years) with actinically damaged skin and a long-standing history of widespread pruritus and prurigo nodules. All patients had histologically confirmed keratoacanthomas, or squamous cell carcinomas with the clinical appearance of a keratoacanthoma, that developed within the field of prurigo nodules. All 7 patients had a clinical response to acitretin with a decrease in the number of lesions. Four patients had an associated eczematous dermatitis and were also treated with cyclosporine with improvement in pruritus and prurigo nodules and no increase in keratoacanthomas.

LIMITATIONS

The retrospective design and small number of patients are limitations to this study.

CONCLUSION

Our case series represents a distinct subset of elderly individuals with extensive actinic damage who we believe are predisposed to developing both prurigo nodules and keratoacanthomas.

Diagnosis and Follow-Up of Keratoacanthoma-Like Lesions: Clinical-Histologic Study of 43 Cases

Background:

Keratoacanthoma (KA) is easily confused with squamous cell carcinoma (SCC) on a clinical or a histopathologic basis. However, KA undergoes spontaneous regression, whereas SCC does not.

Objective:

Our objective was to study the histopathologic features associated with clinical regression in KA-like lesions to support the therapeutic option.

Methods:

Forty-three biopsies of KA-like lesions were taken at patient admission. One month later, surgical excision was performed in 18 growing lesions. Regressing lesions were left untreated. Classic histopathologic features and diagnosis were blindly recorded in both biopsies and surgical specimens.

Results:

On a clinical and a histologic basis, 32 lesions were assessed as KA and 11 as SCC. Features that indicated malignancy were observed in both groups, but the probability of SCC was 31 times higher in tumors with five or more of such features. Several of the histologically atypical lesions were found to regress.

Conclusion:

SCCs and KAs have more pathologic similarities than differences, especially in the proliferative phase. The combination of the most useful features did not allow the nosologic diagnosis in difficult cases but helped. Differential diagnosis was easier to determine after the 1-month follow up. Complete surgical excision should be indicated in nonregressing and growing lesions.

Keratoacanthoma developing in previous cryotherapy site for solar keratosis

Keratoacanthoma is a relatively common benign squamous neoplasm that may show spontaneous clearing. Although the cause of the tumour is unknown, there are some reports describing keratoacanthoma following various types of trauma or secondary to other skin lesions. Thermal burns are reported to be important preceding traumas in the development of keratoacanthomas. whereas there is only one report of cold trauma of cryotherapy. We report a rare case of keratoacanthoma arising in the site of cryotherapy applied for solar keratosis.

Keratoacanthoma: A Clinico-Pathologic Enigma

BACKGROUND

Keratoacanthoma (KA) is an extraordinary entity. Once considered a benign neoplasm that resembled a highly malignant one (pseudomalignancy), it is now viewed in an opposite light as a cancer that resembles a benign neoplasm (pseudobenignity).

OBJECTIVE

The goal was to delineate the malignant potential of this neoplasm based on the author's experience and a review of recent data and research and to emphasize the KA as a possible part of an autosomal dominant familial cancer syndrome, the Muir-Torre syndrome.

METHODS

This is a review of the literature.

RESULTS

In this work, the KA is reviewed with recent advances emphasized.

CONCLUSION

KA is an abortive malignancy that rarely progresses into an invasive SCC. The KA may serve as a marker for the important autosomal dominant familial cancer syndrome, the Muir-Torre syndrome, as a result of a defective DNA mismatch repair gene.