Lupus Erythematosus–Lichen Planus Overlap Syndrome

Cicatricial alopecia, also referred to as scarring alopecia, encompasses a heterogeneous group of disorders characterized by irreversible destruction of the hair follicle and replacement with fibrous tissue. Once follicular stem cell niches are lost, hair regrowth is no longer possible, making early recognition and intervention essential. Cicatricial alopecias are broadly divided into primary and secondary forms. In primary cicatricial alopecia, the hair follicle itself is the principal target of inflammation, whereas in secondary forms, follicles are destroyed as collateral damage from broader cutaneous pathology.

Despite the availability of several classification systems, the diagnosis of primary cicatricial alopecia remains challenging. The most widely accepted framework is that proposed by the American Hair Research Society (AHRS), which categorizes these disorders according to the predominant inflammatory cell type observed on scalp biopsy (lymphocytic, neutrophilic, mixed, or nonspecific). While useful, this schema does not fully account for atypical or hybrid presentations, and a subset of patients exhibit overlapping clinical, histopathologic, and immunologic features that defy strict categorization.

One such rare and diagnostically complex entity is lupus erythematosus–lichen planus overlap syndrome (LE/LP overlap syndrome). This condition is characterized by concurrent or intermixed features of cutaneous lupus erythematosus (most commonly discoid lupus erythematosus) and lichen planus or its follicular variant, lichen planopilaris. The rarity of the condition has limited systematic study, and much of the literature consists of isolated case reports and small case series. Consequently, uncertainty remains as to whether LE/LP overlap syndrome represents a distinct nosologic entity, a variant of lupus erythematosus with lichenoid features, or lichen planopilaris with superimposed lupus pathology.

Clinical Features: Understanding the clinical manifestations of LE/LP overlap syndrome requires familiarity with the defining characteristics of both parent diseases.

Lichen planus is a chronic inflammatory disorder of the skin and mucous membranes, classically presenting with violaceous, polygonal, flat-topped papules and plaques. Pruritus is often prominent. When the scalp is involved, the condition is referred to as lichen planopilaris, a lymphocytic cicatricial alopecia marked by perifollicular erythema, follicular hyperkeratosis, and progressive permanent hair loss.

Cutaneous lupus erythematosus, particularly discoid lupus erythematosus, manifests as well-demarcated erythematous plaques with adherent scale, follicular plugging, and eventual atrophy and scarring. Lesions favor sun-exposed sites, including the face, ears, and scalp. Scalp involvement frequently leads to scarring alopecia, often with dyspigmentation and textural skin changes.

In LE/LP overlap syndrome, patients exhibit a mixture of these features, either simultaneously or sequentially. Scalp lesions may present as erythematous or violaceous patches with perifollicular scale and plugging, evolving into areas of scarring alopecia. Clinically, lesions may be difficult to distinguish from classic discoid lupus erythematosus or lichen planopilaris alone. Extra-scalp involvement can include the face, trunk, extremities, palms, soles, and mucosal surfaces. Acral involvement, annular or violaceous plaques, and hyperkeratotic or wart-like lesions have all been described.

Importantly, the clinical course may be indolent or relapsing, and disease activity may wax and wane over years. Some patients initially present with features typical of one disease, only to later develop signs suggestive of the other, further complicating diagnosis.

Pathology and Diagnostic Considerations: Scalp biopsy is indispensable in the evaluation of suspected LE/LP overlap syndrome. However, histopathologic interpretation can be challenging, particularly if disease activity is low or scarring is advanced.

Histologic features of lichen planopilaris include a lichenoid lymphocytic infiltrate targeting the follicular epithelium, basal cell vacuolar degeneration, apoptotic keratinocytes, and concentric perifollicular fibrosis. In contrast, discoid lupus erythematosus typically shows interface dermatitis involving both follicular and interfollicular epidermis, thickening of the basement membrane, follicular plugging, dermal mucin deposition, and perivascular and periadnexal lymphocytic infiltrates.

In LE/LP overlap syndrome, biopsy specimens may demonstrate overlapping or intermediate features of both conditions. Some cases show prominent follicular interface dermatitis resembling lichen planopilaris, alongside basement membrane thickening or dermal mucin more characteristic of lupus erythematosus. Serial biopsies may be required, as histologic features can evolve over time.

Direct immunofluorescence (DIF) can provide additional diagnostic insight. In lupus erythematosus, DIF classically demonstrates granular deposition of immunoglobulins and complement along the dermoepidermal junction (the “lupus band”). In lichen planus, DIF often reveals fibrinogen deposition along the basement membrane zone. In overlap syndrome, DIF findings may be incomplete, atypical, or mixed, and absence of a classic lupus band does not exclude the diagnosis.

Given these complexities, clinicopathologic correlation is essential. Diagnosis should integrate clinical morphology, disease distribution, histopathology, immunopathology, and, where relevant, serologic testing.

Immunopathogenesis and Disease Relationships: Both lupus erythematosus and lichen planus are immune-mediated disorders characterized by cytotoxic T-cell responses against basal keratinocytes. Shared pathogenic mechanisms include interface dermatitis, dysregulated apoptosis, and aberrant immune activation at the dermoepidermal junction. These commonalities may partly explain the occurrence of overlap syndromes.

Whether LE/LP overlap syndrome represents a distinct autoimmune entity remains unresolved. Some authors propose that it reflects a spectrum of interface dermatitis, with lupus erythematosus and lichen planus representing poles of a shared pathogenic process. Others suggest that genetic predisposition, environmental triggers (including ultraviolet exposure), or epitope spreading may drive the coexistence of both diseases in susceptible individuals.

Treatment and Management: There is no standardized or evidence-based treatment regimen specifically established for LE/LP overlap syndrome. Management strategies are therefore extrapolated from therapies used for discoid lupus erythematosus and lichen planopilaris, with treatment tailored to disease severity, activity, and extent.

First-line therapies often include high-potency topical corticosteroids and intralesional corticosteroid injections for localized active lesions. Topical calcineurin inhibitors may be considered in sensitive areas or as steroid-sparing agents. For more extensive or progressive disease, systemic therapy is frequently required.

Antimalarial agents, particularly hydroxychloroquine, are commonly used given their efficacy in cutaneous lupus erythematosus and acceptable safety profile. Systemic corticosteroids may be employed for short-term disease control in severe flares, though long-term use is limited by adverse effects. Additional immunomodulatory or immunosuppressive agents, such as methotrexate, mycophenolate mofetil, azathioprine, or retinoids, have been used in refractory cases, though evidence is limited to anecdotal reports.

Because scarring alopecia is irreversible once established, the primary therapeutic goal is to suppress inflammation and halt disease progression rather than restore lost hair.

Prognosis and Systemic Implications: The long-term prognosis of LE/LP overlap syndrome is not well defined. While many patients exhibit disease confined to the skin and scalp, there is concern that some individuals may subsequently develop systemic lupus erythematosus. As a result, ongoing clinical surveillance and periodic systemic evaluation are advisable, particularly in patients with suggestive symptoms or serologic abnormalities.

Conclusion: Lupus erythematosus–lichen planus overlap syndrome is a rare and incompletely understood cause of cicatricial alopecia, characterized by overlapping clinical, histologic, and immunopathologic features of two distinct autoimmune dermatoses. Diagnostic uncertainty is common, and careful clinicopathologic correlation is essential. At present, treatment is empirical and extrapolated from related conditions, underscoring the need for further research. Improved understanding of shared immune mechanisms, follicular biology, and genetic susceptibility may ultimately clarify disease classification and enable more targeted therapeutic approaches.

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