Keratoacanthoma arising in hypertrophic lichen planus

Hypertrophic Lichen Planus: An Up-to-Date Review and Differential Diagnosis

CONTEXT.—

Hypertrophic lichen planus (HLP) is a variant of lichen planus that can be difficult to diagnose based on histopathologic features alone. Thus, patient clinical history and clinicopathologic correlation are essential considerations to make the correct diagnosis.

OBJECTIVE.—

To discuss the clinical and histologic presentation of HLP and provide a thorough review of commonly encountered mimickers in the differential diagnosis.

DATA SOURCES.—

Data were derived from a literature review, personal clinical and research experiences, and a review of cases in the archives of a tertiary care referral center.

CONCLUSIONS.—

In general, HLP involves the lower extremities and is characterized by thickened, scaly nodules and plaques that are often pruritic and chronic in nature. HLP affects both males and females and is most common in adults 50 to 75 years of age. Unlike conventional lichen planus, HLP tends to have eosinophils and classically displays a lymphocytic infiltrate most concentrated around the tips of rete ridges. The differential diagnosis for HLP is broad and encompasses numerous entities in many different categories, including premalignant and malignant neoplasms, reactive squamoproliferative tumors, benign epidermal neoplasms, connective tissue disease, autoimmune bullous disease, infection, and drug-related reactions. Therefore, a high index of suspicion must be maintained to avoid a misdiagnosis and potential inappropriate treatments.

To treat or not to treat: PD-L1 inhibitor-induced keratoacanthoma and squamous cell carcinoma

Keratoacanthoma (KA) and squamous cell carcinoma (SCC) are rare side effects of programmed cell death ligand-1 (PD-L1) inhibitors that can disrupt therapy. There is no consensus on optimal treatment. We investigated the management strategy and factors influencing pathophysiology. An institutional cancer registry and literature search were used for this retrospective study. Only PD-L1-induced KA and SCC cases were included. Pathology specimens were stained with immune markers and management strategies were analyzed. Four cases were identified at our institution. Immunohistochemistry of atypical keratinocytes revealed PD-1/PD-L1 positivity, high p53, and low bcl-2 for all cases with differential expression of CD44 and beta-catenin for KA versus SCC. Nivolumab was continued or temporarily held with complete resolution. In addition, a literature search identified 30 additional cases of KA/SCC after PDL-1 inhibitor use. The most common treatment was excision/destruction followed by topical and/or intralesional corticosteroids. Therapy was definitely withheld in 22% of KA patients and in 9% of SCC cases. The expression of PD-L1 by atypical keratinocytes helps to explain the effects of nivolumab on the development of cutaneous neoplasms. The expression of immune markers provides mechanistic insights into pathophysiology. Management may be achieved with conservative therapy and without treatment interruption.

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.

Malignant epithelial tumors: Part I. Pathophysiology and clinical features

Epithelial skin cancer is a major burden for western societies. In the 21(st) century there will be a steady increase in the incidence of these tumors in the elderly population. The article summarizes the pathophysiology of epithelial tumors and gives a systematic outline of the different clinical features of keratinocytic tumors. Furthermore, the article gives an overview of inherited syndromes that predispose to malignant epithelial tumors.

Giant keratoacanthoma arising in hypertrophic lichen planus

A 45-year-old man presented with a rapidly enlarging tumour in an area of long-standing hypertrophic lichen planus of the lower leg. Histological examination of the resected specimen showed it to be a giant keratoacanthoma measuring 37 x 57 mm. Neoplastic change is a rarely reported complication of chronic variants of cutaneous lichen planus. To date there have been only two reports of keratoacanthoma development in association with lichen planus.