An isoradiotopic response of lichen planus: a case report and review of literature
Article information
Abstract
Radiation-induced cutaneous side effects are well known; however, the isoradiotopic phenomenon presenting as lichen planus is underreported in the literature. It is imperative to be aware of this entity to manage the patients accordingly. Herein, we report a 31-year-old male, a known case of carcinoma glottis who developed lichen planus confined to the radiation site and presented with a review of literature on isoradiotopic lichen planus.
Introduction
Cutaneous side effects of radiation therapy (RT) are well known and include radiation dermatitis, and recall phenomena familiar to dermatologists and to treating oncologists. However, the isoradiotopic response defined as a phenomenon of secondary dermatoses occurring at the site of radiation is often underdiagnosed and reported. Lichen planus as an isoradiotopic response has been rare with only 11 cases reported in the literature till date [1,2]. Hence this case is reported along with a literature review on the isoradiotopic response of lichen planus.
Case Report
A 31-year-old male, Dravidian, a known case of carcinoma glottis (squamous cell carcinoma), stage T1aN0Mx was treated with a total radiation dose of 63 Gy delivered in 28 fractions over 5 weeks and 3 days, with 5 fractions administered weekly. Volumetric arc therapy was employed using 4 arcs: 2 clockwise and 2 counterclockwise, delivered with a 6 MV flattening free filter linear accelerator (Halcyon; Varian Medical Systems, Palo Alto, CA, USA) (Fig. 1A, 1B). A bolus was utilized for planning and treatment delivery. The skin 3 mm Dmax dose was 67.5 Gy and the skin 5 mm Dmax dose was 68.6 Gy. He presented to our outpatient department with itchy skin lesions confined to the site of radiation of 10 days duration after 42 days of RT. The skin lesions appeared after one and a half months of RT. There was no prior history of similar skin lesions and he denied any drug history before the onset of skin lesions. Cutaneous examination revealed multiple discrete, asymmetrically distributed, violaceous, annular plaques confined to the site of radiation (Fig. 2). Examination of Palms, soles, oral cavity, and genitalia were non-contributory. Dermoscopy (Dermlite,10×, polarized mode) revealed Wickham’s striae at the periphery of the lesions (Fig. 3). Differential diagnoses of radiation-induced lichen planus, cutaneous metastasis, and radiation dermatitis were considered. Histopathology of the violaceous plaque demonstrated ortho keratotic epidermis, mild perivascular infiltrate in the dermis, and focal pigment incontinence with focal lichenoid inflammatory infiltrate in the dermis, suggestive of lichen planus (Fig. 4A, 4B). The patient was prescribed topical steroid application (beclomethasone dipropionate cream 0.025% twice a day) for 2 weeks following which the patient had 80% resolution of skin lesions. The patient was followed up for a year and at 1 year, he did not develop new skin lesions.
(A, B) Representative images of the radiation therapy provided for the patient.
Multiple discrete violaceous, annular plaques confined to the site of radiation.
Dermoscopy (Dermlite, 10×, polarized mode) showing Wickham’s striae at the periphery of the lesions.
Skin biopsy showing ortho keratotic epidermis, mild perivascular infiltrate in the dermis, and focal pigment incontinence with focal lichenoid inflammatory infiltrate in the dermis (A, hematoxylin and eosin (H&E), ×10; B, H&E, ×40).
Discussion
The isoradiotopic response described by Shurman et al. in 2004 is a rare side effect of RT referring to the development of secondary dermatosis confined to the site of radiation which is a type of wolf’s isotopic response [3-5]. The other dermatoses that have been reported as isoradiotopic responses include localized bullous pemphigoid, pemphigus vulgaris, pemphigus foliaceous, benign mucosal pemphigoid, paraneoplastic pemphigus, discoid lupus erythematosus, hidradenitis suppurativa, morphea, lichen sclerosis et atrophicus, chronic graft versus host disease, and lichen planus [1]. Among these, bullous pemphigoid occurring at the site of RT has been a well-established entity, and lichen planus as an isoradiotopic response is rare with only 11 cases reported in the literature. The various kinds of isoradiotopic responses of lichen planus reported in the literature are summarized in Table 1 [3,5-14]. The latency to develop skin lesions at the site of radiation ranges from 1–4 months and our patient developed skin lesions after 1.5 months of radiation [6]. Eichbaum et al. [8] were the first to report the secondary generalization of radiation-induced lichen planus and since then, there have been reports on an extension to non-irradiated areas and progression to generalized lichen planus. The pathogenesis of radiation-induced lichen planus is poorly understood. CD8+ cytotoxic T cells and natural killer cells are believed to cause keratinocyte damage at the dermo-epidermal junction in skin affected by lichen planus. This damage to the basement membrane allows more CD8+ cells to infiltrate leading to chronicity [3,7]. It has been proposed that RT may induce a lichenoid reaction owing to cellular injury and release of keratinocyte self-antigens, thereby instigating a local inflammatory response [2]. RT through immunomodulatory effects can in addition induce the expression of proinflammatory molecules such as major histocompatibility complex, cytokines (interleukin [IL]-1, IL-6, IL-8, tumor necrosis factor α, and transforming growth factor β), and adhesion molecules (intercellular adhesion molecule 1 and E-selectin) through unclear mechanisms. It has been thought that an increase in the expression of adhesion molecules may induce the trans-endothelial migration of leucocytes and facilitate the migration of leukocytes, including CD8+ cytotoxic T cells, which contributes to the characteristic bandlike lymphocytic infiltrate in lichen planus. Loss of self-tolerance combined with antigen exposure has also been a proposed hypothesis for the development of lichen planus [2]. Alteration of lymph flow and neuro-immune signaling are other hypothetical explanations for the altered local immune response [15]. They respond well to topical therapies like topical steroids, and calcineurin inhibitors.
Review of literature of cases reported with isoradiotopic response
Radiation-induced lichen planus is an uncommon occurrence. This case highlights the importance of diagnosing radiation-induced isotopic response prompting a dermatology referral among oncologists for optimal patient of these patients.
Notes
Statement of Ethics
Written informed consent was obtained from the patient for the publication of the details regarding the patient. Institute ethics approval is not applicable as it is a case report.
Conflict of Interest
No potential conflict of interest relevant to this article was reported.
Funding
None.
Author Contributions
Conceptualization, AS, GSA, MM; Data curation, AS, GSA, MM, BHS, GK; Investigation, AS, GSA, MM, BHS, GK; Methodology, AS, GSA, MM; Writing - original draft, AS; Writing - review and editing, MM, BHS, GK.
Data Availability Statement
All data generated or analyzed during the study are included in this published article.