Isolated Actinic Prurigo Cheilitis in an Elderly Thai Female: An Atypical Presentation

Abstract

Actinic prurigo (AP) is a rare photodermatosis with variable clinical presentations across different ethnic populations. While lip involvement is common in Latin American populations, isolated cheilitis as the sole manifestation in elderly Asian patients has not been previously documented. We report a 67-year-old Thai female presenting with chronic, recurrent painful ulcers on the lower lip persisting for six months. Despite multiple treatments at a private clinic, new lesions continued to develop. Dermatological examination revealed multiple erosions on an erythematous, edematous plaque at the vermilion border of the lower lip. Histopathological examination demonstrated dense lymphocytic infiltration with well-defined lymphoid follicles, demonstrating the histopathological pattern of follicular cheilitis, which is pathognomonic for actinic prurigo cheilitis. Interestingly, phototesting and photoprovocation yielded normal results across all UV spectra. Complete remission was achieved after two months of treatment with topical 1.25% hydrocortisone cream combined with strict sun protection measures. This case highlights an unusual phenotype of actinic prurigo in an Asian patient, characterized by isolated lip involvement in the absence of other cutaneous manifestations. It underscores the importance of considering AP in the differential diagnosis of chronic lip lesions, even in atypical demographics and with normal phototesting results. The favorable response to conservative management emphasizes the value of early recognition and appropriate treatment.

Introduction

Actinic prurigo (AP) is an idiopathic photodermatosis characterized by abnormal inflammatory responses to sunlight exposure.¹ The disease demonstrates marked geographic variation, with highest prevalence in Mestizo and Native American populations in high-altitude Latin American regions.² Emerging reports suggest more diverse clinical phenotypes, particularly in Asian populations.^3,4

Lip involvement in AP, termed AP cheilitis, typically accompanies other sun-exposed skin lesions and represents a hallmark feature in Latin American cohorts.⁵ Histologically, AP cheilitis exhibits well-organized lymphoid follicles within the dermis, a pattern termed follicular cheilitis, which is considered pathognomonic for this condition.⁶ However, isolated lip lesions as the sole manifestation of AP remain exceptionally rare, particularly in elderly Asian patients. Herein, we present AP cheilitis in a 67-year-old Thai female, representing an atypical presentation that broadens our understanding of this photodermatosis.

Case Presentation

A 67-year-old Thai female presented with a six-month history of chronic, recurrent painful lower lip erosions. Despite treatment at multiple clinics with topical and oral medications, only partial improvement occurred, with new lesions continuing to develop. Her medical history included hypertension and hyperlipidemia, well-managed with amlodipine, simvastatin, and losartan for approximately 6 years. No recent exposure to new medications or cosmetic products was reported. She denied food or drug allergies but reported extensive sun exposure during younger years. No family history of photosensitivity disorders existed.

Dermatological examination revealed multiple erosions on an erythematous, edematous plaque localized to the lower lip vermilion border, without intraoral mucosal involvement (Figure 1). Other cutaneous examination including sun-exposed areas (ie, face, neck, dorsal hands, forearms) revealed no additional cutaneous lesions. Conjunctivae appeared normal bilaterally. Initial differential diagnoses included actinic cheilitis, discoid lupus erythematosus, erosive lichen planus, and contact cheilitis.

Figure 1.

Clinical presentation at baseline showing multiple erosions on an erythematous, edematous plaque at the lower lip (arrows).

A 4-mm punch biopsy from lower lip demonstrated epidermal acanthosis, spongiosis and parakeratosis. The lamina propria exhibited a diffuse lymphoplasmacytic infiltrate with well-formed lymphoid follicles and congested blood vessels (Figure 2). These findings were consistent with follicular cheilitis, a characteristic feature of AP cheilitis.⁶ Phototesting showed minimal erythema doses (MED) for UVA, UVB, and visible light within normal limits. Photoprovocation testing across the entire UV spectrum yielded negative results. The patient received topical 1.25% hydrocortisone cream twice daily with comprehensive photoprotection measures, including broad-spectrum sunscreen (SPF 50+ with UVA and UVB protection), photoprotective lip balm (SPF 30+, reapplied after eating/drinking), and wide-brimmed hats. At two-month follow-up, complete remission was documented (Figure 3). The patient reported no new lesions with good photoprotection adherence and remained asymptomatic at six-month follow-up.

Figure 2.

A 4-mm punch biopsy obtained from the lower lip demonstrated epidermal acanthosis, spongiosis, and parakeratosis. The underlying lamina propria showed a diffuse lymphoplasmacytic infiltrate with well-formed lymphoid follicles and congested blood vessels. (hematoxylin-eosin at 100x magnification). Arrows highlight the lymphoid follicles.

Figure 3.

Two-month follow-up demonstrating complete resolution following treatment with topical 1.25% hydrocortisone cream and photoprotection measures.

Discussion

AP demonstrates remarkable geographic and ethnic variability. The disease predominantly affects individuals in high-altitude regions (>1000 meters above sea level) with intense UV exposure.² Prevalence of AP ranges from 0.003% - 8%,⁷ with highest rates in Latin American Mestizo populations^5,8 and Native Americans (Amerindians).^9,10 While initially considered rare outside Latin America, increasing Asian and European case reports have expanded understanding of global distribution.^3,11–15 Classic cases typically manifest in the first decade with chronic, relapsing course and female predominance.^2,7,10 Adult-onset disease, as in our patient, represents an increasingly recognized variant.

Clinical manifestations of AP are polymorphic, characterized by intensely pruritic erythematous papules coalescing into plaques on sun-exposed areas,^1,5 with secondary excoriations, lichenification, and eczematization. Lesions typically affect the face, neck, anterior chest, extensor forearms, and dorsal hands symmetrically.^2,10 Lips and conjunctival involvement commonly occur in Mestizo and Native American populations.^5,8,16 Remarkably, lip lesions may occasionally represent the sole manifestation, as demonstrated in our case.^5,8,17,18 Asian populations demonstrate significant phenotypic differences from that observed in Latin American cohorts. Asian patients more frequently present with male predominance and later age of onset. Lip and conjunctival involvement are notably uncommon.^3,12–14 To our knowledge, our patient represents the first Asian case with isolated lip involvement. Table 1 summarizes previously reported cases of AP cheilitis.^{5,6,8,17–19}

Table 1.

Characteristics of Actinic Prurigo Cheilitis in Previous Literature

No.	Authors, Year	Population	Age at Onset	Sex Predominance	Number of Cases	Number of Cases with Isolated Lip Involvement
1	Mounsdon et al, 198817	USA	61 and 69 years	Female	5	2 (40%)
2	Herrera-Geopfert and Magaña, 19956	Mexico	8-66 years	Female	57	9 (15.7%)
3	Vega-Memije et al, 20028	Mexico	9-82 years	Female	116	32 (27.6%)
4	Miranda et al, 201418	Brazil	63 and 58 years	Female	2	2 (100%)
5	Plaza et al, 20165	Multi-center	3-67 years	Female	75	42 (56%)
6	Acuña et al, 201819		25 years	Female	1	1 (100%)
7	Current case	Thailand	67 years	Female	1	1 (100%)

AP cheilitis clinically presents with scaling, fissures, erythema, edema, and ulceration, mimicking actinic cheilitis.¹⁹ Histologically, characteristic features include acanthosis with spongiosis, basal cell vacuolation, and dense lymphocytic infiltrate forming well-defined follicles.⁶ These follicles exhibit T cells at the periphery and B cells within germinal centers. This pattern, designated follicular cheilitis, represents the pathognomonic feature of AP cheilitis.⁶ Variable eosinophils and macrophages may be present at the epithelial-connective tissue interface, though sensitivity and specificity are only 75% and 36.4%, respectively.^5,6 Differential diagnoses for isolated lip lesions include actinic cheilitis, granulomatous cheilitis, contact cheilitis, erosive lichen planus, and discoid lupus erythematosus.⁵ Actinic cheilitis shows chronic sun damage and lacks lymphoid follicles, while erosive lichen planus features Wickham striae and interface dermatitis. Discoid lupus erythematosus presents with interface dermatitis and mucin deposition. Contact cheilitis has an acute onset linked to allergens, and granulomatous cheilitis displays persistent edema with non-caseating granulomas. The presence of lymphoid follicles in the biopsy confirmed AP cheilitis, ruling out these alternatives. Key distinguishing characteristics of these conditions are summarized in Table 2.^20–22

Table 2.

Differential Diagnosis of Follicular Cheilitis and Disease Characteristics

Condition	Clinical Features	Histopathological Features	Key Distinguishing Features
Actinic prurigo cheilitis	Erosions, scaling, edema; recurrent; sun exposure history	Lymphoid follicles, spongiosis, plasma cells	Follicular cheilitis pattern; positive family history
Actinic cheilitis	Scaling, atrophy, white plaques; lower lip predominance	Solar elastosis, dysplasia (variable degrees)	Chronic sun damage; risk for malignant transformation
Erosive lichen planus	Wickham striae, erosions, pain; oral involvement common	Interface dermatitis, colloid bodies, band-like infiltrate	Reticular pattern; oral mucosal involvement
Discoid lupus erythematosus	Erythema, scaling, atrophy, hyperpigmentation	Interface dermatitis, deep perivascular infiltrate, mucin	Systemic features possible; positive ANA
Contact cheilitis	Acute onset, pruritus, history of allergen exposure	Spongiosis, superficial perivascular infiltrate	Clear temporal relationship with contactant
Granulomatous cheilitis	Persistent swelling, fissuring; may be part of Melkersson-Rosenthal syndrome	Non-caseating granulomas	Persistent edema; facial nerve involvement in Melkersson-Rosenthal syndrome

The pathogenesis of AP involves type IV hypersensitivity to UV radiation, with both Th1 and Th2 responses.²³ UV-stimulated keratinocytes produce tumor necrosis factor (TNF)-α, while Th1 cells release proinflammatory cytokines and Th2 cells contribute interleukin (IL)-4, IL-5, and recruit mast cells and eosinophils.^23–26 Consequently, the intrinsic apoptotic pathway implicates the final step of the reaction.^24,27 Torres-Alvarez et al reported persistent epidermal Langerhans cell counts following UV exposure in AP-affected individuals, contrasting with typical decreases in healthy controls, suggesting Langerhans cell activation.²⁸

Several risk factors have been implicated in disease pathogenesis. While UV exposure remains the most extensively studied environmental trigger, genetic susceptibility plays a critical role.^29,30 Strong genetic associations exist with HLA-DR4 (particularly DRB1*0407) in Mexican populations,³¹ HLA-DRB1*14 in Canadian populations,⁹ and HLA-DRB1*03:01 in Asian cohorts.^4,12

Phototesting in AP may yield variable results, with a reduced or normal MED.^1,14,32 Our patient demonstrated normal phototesting and photoprovocation across the entire UV spectrum, in contrast to typically positive photoprovocation in previous reports.^13,14 These findings suggest that AP should remain in the differential diagnosis even when phototesting is negative, provided the histopathologic features are characteristic.

Although individuals with skin of color possess higher baseline melanin levels providing inherent photoprotection, they remain susceptible to photodermatoses such as AP. Asian populations have an estimated natural SPF of 13.4, which is insufficient to prevent chronic UV-induced damage.^33–35 The lips present unique challenges due to lower melanin density, environmental exposure, and frequent disruption of applied photoprotective agents through eating and drinking, necessitating particular attention in AP cheilitis management. For our patient, we emphasized the critical importance of comprehensive photoprotection tailored to her skin type and specific anatomical involvement. We also counseled the patient that consistent photoprotection was essential to prevent disease recurrence, as UV radiation can trigger AP regardless of baseline skin pigmentation.³⁶

Strict photoprotection constitutes the cornerstone of AP management, including protective clothing, wide-brimmed hats, sunglasses, and broad-spectrum sunscreen.⁵ Thalidomide remains the most effective treatment due to selective TNF-α inhibition and suppression of Langerhans cell antigen-presenting capacity.^37–40 Notably, therapeutic response to thalidomide may serve as a diagnostic indicator for AP; however, its use is limited by significant teratogenicity and requires strict contraceptive measures and monitoring protocols. Topical and systemic corticosteroids effectively control pruritus and eczematous lesions during acute exacerbations.^2,5,41 Alternative therapeutic options include antimalarials, calcineurin inhibitors, janus kinase inhibitors, and phototherapy.^2,42

AP typically follows a chronic, relapsing course with seasonal exacerbations.^2,7 While childhood-onset disease may improve after puberty in some patients, adult-onset cases tend to demonstrate a more persistent trajectory.^2,3,14 Lip involvement, as seen in our patient, presents particular therapeutic challenges due to the difficulty of achieving complete photoprotection in this anatomical site and the chronic nature of cheilitis.^8,43 However, with rigorous photoprotection and appropriate anti-inflammatory therapy, symptomatic control can be achieved. Long-term follow-up is recommended to monitor for recurrence and ensure continued adherence to photoprotective measures.⁷

Conclusion

Our patient represents a rare case of isolated AP cheilitis in a 67-year-old Asian female. This case highlights several atypical features: isolated labial involvement without other cutaneous lesions, adult onset in an elderly patient, occurrence in an Asian population where AP is less commonly reported, and negative phototesting despite characteristic histopathology. Reporting such cases enhances clinical awareness and underscores the importance of considering AP cheilitis in the differential diagnosis of chronic lip erosions, even when phototesting is negative and the patient’s demographic profile is atypical.

Funding Statement

No sources of funding were used to prepare this paper.

Ethics Approval and Consent to Participate

This article was performed in accordance with the principles of Declaration of Helsinki. Ethical approval was exempted by the Ethics Committee of the Faculty of Medicine, Ramathibodi Hospital, Mahidol University. The patient provided explicit consent for the use of clinical photographs and histopathological images for educational and research purposes. Patient anonymity has been preserved throughout this paper, and no identifying information has been disclosed.

Disclosure

The authors declare that this paper was prepared in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.