Generalized hypertrophic lichen planus in an adolescent male initially misdiagnosed as fungal infection: a case report

¹Internal Medicine Department, Sekou Toure Regional Referral Hospital, Mwanza, Tanzania, ²Internal Medicine Department, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania, ³Regional Dermatology Training Centre, Kilimanjaro Christian Medical Centre University, Kilimanjaro, Tanzania, ⁴Histopathology and Morbid Anatomy Department, Bugando Medical Centre (BMC), Mwanza, Tanzania, ⁵Department of Pathology, Catholic University of Health and Allied Sciences (CUHAS), Mwanza, Tanzania, ⁶Internal Medicine Department, Muhimbili National Hospital, Dar es Salaam, Tanzania

^&Corresponding author
Oswin Mwemezi, Internal Medicine Department, Sekou Toure Regional Referral Hospital, Mwanza, Tanzania

Introduction    

Lichen planus is a chronic inflammatory dermatosis of unknown etiology affecting approximately 1% of the general population [1]. It typically presents with pruritic, polygonal, violaceous, flat-topped papules and plaques [2]. Although it most commonly affects middle-aged adults, it may also occur in adolescents and children [3]. The pathogenesis is thought to involve a T cell-mediated autoimmune response directed against basal keratinocytes [3]. Several clinical variants of lichen planus have been described, including hypertrophic, annular, actinic, and pigmented forms [4]. Hypertrophic lichen planus is characterized by thick hyperkeratotic plaques, usually affecting the extensor surfaces of the limbs. It may mimic other dermatological conditions such as plaque psoriasis, chronic eczema, and dermatophytosis [1]. Because of this resemblance, misdiagnosis is quite common. Despite being well described, generalized hypertrophic lichen planus in adolescents is uncommon and may present significant diagnostic challenges, particularly in resource-limited settings where dermoscopy is not readily available and empirical treatment is the norm. We report a case of generalized hypertrophic lichen planus in an adolescent male initially misdiagnosed as a fungal infection, highlighting diagnostic pitfalls and the importance of early histopathological confirmation.

Patient and observation     

Patient information: an 18-year-old male presented with a four-month history of progressively worsening intensely pruritic skin lesions affecting the upper limbs, lower limbs, and trunk. The lesions initially appeared as small papules and gradually increased in size and number. Before presentation, the patient had been treated empirically for presumed fungal infection and cellulitis without clinical improvement. There was no history of chronic illness such as diabetes mellitus, hypertension, HIV, or viral hepatitis infections. He reported frequent use of topical antifungal medications but denied a family history of a similar disease.

Clinical findings: a dermatological examination revealed generalized, symmetrical, well-demarcated hyperpigmented hyperkeratotic plaques, predominantly involving the extensor surfaces of the upper limbs, flexural surfaces of lower limbs, trunk, and dorsum of hands (Figure 1 and Figure 2). The lesions were polygonal and annular in morphology with adherent scales and portrayed evidence of Koebnerization (Figure 2). His lips were dry and fissured with well-defined hyperkeratotic plaques (Figure 3). He had a few plaques on the scalp, but nails and mucosal surfaces were uninvolved. Dermoscopy was not performed due to its unavailability.

Timeline of current episode: when the lesions first occurred, he was diagnosed with a generalized dermatophytosis and treated with antifungals for two months. Despite his good adherence to the therapy, skin lesions continued to progress rapidly until he was referred to our facility, where a clinical diagnosis of lichen planus was made. A skin biopsy for histopathology was performed, and treatment with oral low-dose methotrexate and glucocorticoids, both systemic and topical, was initiated. Histopathology two weeks later confirmed the diagnosis of lichen planus, and thus the same treatment was continued. Six weeks after initiation of therapy, the patient demonstrated marked clinical improvement with a significant reduction in pruritus and flattening of lesions with no new lesions occurring (Figure 4, Figure 5, and Figure 6).

Diagnostic assessment: laboratory investigations, including complete blood count, fasting blood glucose, renal and liver function tests, were normal. Serologies for HIV, viral hepatitis B, and C came back negative. Viral hepatitis serologies are relevant as lichen planus has been associated with hepatitis C infection in some populations [3]. Histopathology of the skin punch biopsy specimen revealed hyperkeratosis, acanthosis, with wedge-shaped hypergranulosis and saw-toothed rete ridges (Figure 7A). A band-like lymphohistiocytic infiltrate obscuring the dermo- epidermal junction was seen together with apoptotic basal keratinocytes, consistent with the diagnosis of lichen planus (Figure 7B, C). Differential diagnoses considered included psoriasis, chronic eczema, dermatophytosis, and hypertrophic lupus erythematosus. These were excluded based on clinical morphology, lack of response to antifungal therapy, and histopathological findings.

Diagnosis: generalized hypertrophic lichen planus.

Therapeutic interventions: due to the extensive disease, the patient was initiated on oral prednisolone at 1mg/kg/day (60mg daily), which was gradually tapered over six weeks. Along with it, topical betamethasone combined with salicylic acid was given. Blood pressure and blood glucose levels were closely monitored during therapy. In addition, low-dose oral methotrexate at 7.5mg weekly was introduced together with folinic acid supplementation, due to evidence supporting its usefulness in extensive cutaneous lichen planus [5].

Follow-up and outcome of interventions: after six weeks of treatment, there was marked clinical improvement with a significant reduction in pruritus and flattening of lesions. Most lesions resolved into post-inflammatory hyperpigmented macules and patches, with no new lesions observed. Mild generalized hypopigmentation was noted, likely secondary to systemic corticosteroid therapy (Figure 5, Figure 6, and Figure 7).

Patient perspective: the patient reported significant relief from itching and improvement in daily functioning and quality of life following treatment.

Patients consent: written informed consent was obtained from the patient for publication of this case report and accompanying images.

Discussion     

Lichen planus is a chronic inflammatory disorder mediated by cytotoxic T cell responses against basal keratinocytes [6]. The hypertrophic variant represents a chronic and often treatment-resistant form characterized by thick hyperkeratotic plaques, typically localized to the lower limbs [7,8]. In contrast, our case demonstrated a generalized involvement, including the trunk and lips, in an adolescent. Such atypical distribution may obscure classical diagnostic clues, leading to misdiagnosis and treatment delays, especially in settings where advanced diagnostic tools such as dermoscopy are not routinely available.

A key challenge in this case was differentiation from other papulosquamous and hyperkeratotic disorders. Psoriasis was considered but excluded due to the absence of the classic silvery scales, a negative Auspitz sign, and a lack of the typical distribution. The plaques involved the extensor surface of the upper limbs more, while in the lower limbs, it was distributed more along the flexural surfaces. Chronic eczema was unlikely given the absence of lichenification, exudation, distribution and the persistent nature. Dermatophytosis was initially presumed; however, lack of response to antifungal therapy and lesion morphology ruled out this diagnosis. Hypertrophic lupus erythematosus was also considered but excluded based on histopathological findings and the absence of systemic features. This case report highlights the critical role of early skin biopsy in atypical or treatment-resistant dermatoses.

Histopathology remains the gold standard for diagnosis, with characteristic features that include hyperkeratosis, wedge-shaped hypergranulosis, sawtooth acanthosis, and a dense band-like lymphocytic infiltrate at the dermo-epidermal junction [8]. In this case, histological findings correlated well with clinical features, confirming the diagnosis. Management of lichen planus depends on disease severity. Topical corticosteroids are the first-line therapy for localized disease, whereas systemic corticosteroids are recommended for severe or generalized involvement [9]. In this patient, systemic corticosteroids were justified due to the generalized distribution and significant functional impairment. Methotrexate was introduced as a steroid-sparing agent, supported by evidence demonstrating its efficacy in generalized and hypertrophic lichen planus through immunomodulation of T cell activity [2,5]. Alternative systemic therapies include acitretin, cyclosporine, and mycophenolate mofetil, particularly in refractory cases. It is important to note that hypertrophic lichen planus has been associated with a small risk of malignant transformation to squamous cell carcinoma, thus calling for a long-term follow-up [9]. This case report demonstrates that early recognition, histopathological confirmation, and evidence-based systemic therapy can result in rapid and favorable outcomes even in atypical and generalized presentations of lichen planus.

Conclusion     

This case describes generalized hypertrophic lichen planus in an adolescent male initially misdiagnosed as a fungal infection, highlighting the importance of early diagnostic reconsideration in treatment-resistant dermatoses. Clinicians should maintain a high index of suspicion and utilize histopathological confirmation to guide appropriate evidence-based management.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Patient management: Oswin Mwemezi and Nancy John Kimario. Data collection: Oswin Mwemezi. Histopathological interpretation: Oscar Ottoman and Gandom Dashtban. Manuscript drafting: Oswin Mwemezi, Nancy John Kimario, Oscar Ottoman, Gandom Dashtban, and Elizabeth Msangi. Manuscript revision: Oswin Mwemezi and Elizabeth Msangi. All the authors have read and approved the final version of this manuscript.

Figures     

Figure 1: upper limbs with multiple well-defined hyperkeratotic papules and plaques with areas of confluence and surface scaling

Figure 2: lower limbs with multiple hyperkeratotic papules and plaques symmetrically distributed with coalescence forming thick plaques

Figure 3: lips with hyperkeratotic plaques with surface scaling

Figure 4: upper limbs with marked resolution of hyperkeratotic lesions with residual post-inflammatory hyperpigmented macules

Figure 5: lower limbs with significant flattening of plaques and reduction of hyperkeratosis with residual post-inflammatory hyperpigmentation of the affected parts

Figure 6: lips with resolved scaling and hyperkeratosis, leaving mild residual hyperpigmentation

Figure 7: A) skin epidermis with hyperkeratosis and acanthosis with saw-toothed rete ridges; hematoxylin and eosin stain (x4 high power field); B) skin epidermis with hyperkeratosis, acanthosis with saw-toothed ridges, and dermal melanophages along the dermal epidermal junction; hematoxylin and eosin stain (x10 high power field); C) band-like lymphohistiocytic infiltrate obscuring the dermal-epidermal junction and area of apoptotic basal keratinocytes pointed by black arrow; hematoxylin and eosin stain (x40 high power field)

References