Squamous Cell Carcinoma Versus Hypertrophic Lichen Planus; a Difficult Differential Diagnosis of Great Significance in Approach to Treatment

Case report: Hypertrophic lichen planus initially misdiagnosed as squamous cell carcinoma

Fewer than 26 case reports describe hypertrophic lichen planus (HLP) misdiagnosed as cutaneous squamous cell carcinoma (cSCC). It can be difficult to distinguish between HLP and cSCC, as these two conditions share many clinical and histopathological characteristics. Patients who are misdiagnosed with cSCC often undergo unnecessary medical and/or surgical interventions before receiving a diagnosis of HLP and improving on HLP-directed therapy. This case series highlights the course of three female patients, referred to a single tertiary institution between 2018 and 2022, who were initially misdiagnosed with cSCC before receiving a diagnosis of HLP. We have emphasized the clinical and histopathological distinguishing features between HLP and cSCC, the pathogenesis of HLP, and current and new HLP-directed therapy. We hope that this case series serves as a reminder to dermatologists, dermatologic surgeons, and dermatopathologists to be aware of this diagnostic challenge.

Widespread Hypertrophic Lichen Planus following Programmed Cell Death Ligand 1 Blockade

Hypertrophic lichen planus (HLP) may not have the typical histological findings of lichen planus and often mimics squamous cell carcinoma (SCC). Distinguishing between the two can pose a diagnostic challenge. Here, we present a case of eruptive HLP mimicking SCC in the context of programmed cell death ligand 1 (PD-L1) immune checkpoint inhibition. A 73-year-old woman recently treated with durvalumab, an anti-PD-L1 antibody, presented to our clinic with diffuse hyperkeratotic papules and plaques previously thought to be eruptive SCC. The lesions did not respond to topical fluorouracil and continued to appear despite discontinuation of immunotherapy. Further histological analysis revealed intraepidermal epithelial proliferation with lichenoid inflammation. Subsequent treatment with topical corticosteroids significantly improved the size and number of lesions. The diagnosis of HLP was made based on histological features and response to topical steroids in the context of recent immunotherapy. This case reveals HLP as a potential adverse effect of PD-L1 inhibition and highlights the need for additional diagnostic assessment in patients presenting with eruptive hyperkeratotic lesions, especially on the lower extremities.

Epidemiologic and Clinical Differences Between Classic and Hypertrophic Lichen Planus in Nigeria

Introduction. Lichen planus is a chronic inflammatory skin disease known to have several clinical variants with attended variable clinical outcomes. Certain complications have been observed in the hypertrophic type, which were not found in association with the classic variant.

Objective: To identify the epidemiologic and clinical differences between the classic and hypertrophic lichen planus and clinical correlates.

Material and Methods. Of 104 participants with lichen planus included in the study, 49 had classic and 55 hypertrophic lichen planus. Demographic and clinical information was obtained. Diagnosis of lichen planus was made clinically and confirmed with histology. The participants were screened for metabolic syndrome, hepatitis B, and C.

Results: Mean age of all patients was 37.20±13.39 years, with no age and gender differences between the participants with classic and hypertrophic lichen planus. Classic lichen planus was more likely to be painful, (8.2% vs 0.0, p=0.046), generalized (95.9% vs 16.4%, p<0.001), involve the oral mucosa (38.8% vs 0.0, p<0.001), the nails (38.8% vs 1.8, p<0.001), present with kobnerisation (55.1% vs 5.5%,<0.001), Wickhiam striae (69.4% vs 16.4%, p<0.001), associated with Hepatitis B vaccination (16.3% vs 3.6%, p<0.028) and anti HCV positivity (16.3% vs 0.0%, p=0.002). Hypertrophic lichen planus was significantly associated with impaired glucose tolerance/diabetes mellitus (16.4% vs 2.0%, p=0.013), dyslipidemia (74.5% vs 40.8%, p=0.001) and saw-tooth histologic appearance compared to classic type.

Conclusion: Hypertrophic lichen planus is more likely to be associated with metabolic complications compared to the classic type. Further studies are needed to loink this difference t chronic inflamation.