Are You Confident of the Diagnosis?
What you should be alert for in the history
Chronic actinic dermatitis (CAD) is a chronic photosensitive eczematous dermatitis. Patients typically present with a pruritic lichenified eruption in photoexposed areas lasting greater than 1 year in duration. In many studies, a duration of eruption for greater than 3 months in the absence of exposure to known photosensitizer is needed to make the diagnosis. Acute exacerbations of this condition classically occur within a few hours to 1 day following sun exposure; therefore, patients often provide a history relating their eruption to sun exposure.
Characteristic findings on physical examination
On physical examination, CAD appears as an eczematous eruption which is usually limited to photoexposed areas. Lichenification is often a hallmark, and hyperpigmented lichenified plaques with an abrupt cutoff at sun-shielded sites is highly characteristic of the disease. Facial involvement often displays sparing of the skin creases in addition to an abrupt cutoff at the neckline (Figure 1).The dorsal hands are also frequently involved, with an abrupt linear cutoff at the dorsal wrists (Figure 2).
Although the sparing of photoprotected sites is characteristic, the eczematous eruption, albeit less intense, may occur on covered areas, presumably due to penetration of ultraviolet radiation (UVR) through clothing. On occasion, the lesions of CAD may mimic cutaneous lymphoma or other infiltrative processes. Diffuse, severe involvement of facial skin in CAD may result in the appearance of leonine fascies. CAD should also be considered in the differential diagnosis of the patient with generalized erythroderma.
Expected results of diagnostic studies
Histopathology is nonspecific for CAD and may demonstrate epidermal spongiosis with a superficial perivascular lymphohistiocytic infiltrate. Atypical mononuclear cells are sometimes present within the epidermis and superficial dermis, which requires differentiation from cutaneous T-cell lymphoma (CTCL). T-cell gene rearrangement may be helpful in these instances.
Phototesting, ie, determination of minimal erythema doses (MED) to UVA and UVB, is a helpful tool in the diagnosis of CAD. About two-thirds of patients with CAD will have decreased MED to both ultraviolet A (UVA) and ultraviolet B (UVB). Approximately one-fourth of patients are sensitive to UVA alone. More rarely, patients may be sensitive to visible light. Severe sensitivity to UVB predicts a poor prognosis.
Patch testing should be considered, as a coexistent contact dermatitis, especially airborne, has been commonly reported in patients with CAD evaluated in the United Kingdom (UK), with up to 74% of CAD patients having a positive patch test. Sesquiterpene lactones from compositae species are commonly identified contact allergens in the UK, but appear to be a less common allergen affecting CAD patients in the United States. Fragrance, colophony, paraphenylendiamine, rubbers and pesticides have also been identified as common sensitizers in CAD patients.
Of note, similar to the general population, benzophenones are the most common cause of photocontact dermatitis to sunscreens in CAD patients. The presence of two or more contact allergens portends a poorer prognosis. Photocontact dermatitis can have a similar clinical appearance to CAD, and in some cases may occur simultaneously. In general, photocontact reactions are rare, but photopatch testing could be undertaken with a CAD-like presentation, especially if the patient relates a history of flaring with sunscreen use.
Other photosensitive dermatoses are in the differential diagnosis of CAD. The classic malar erythema of acute cutaneous lupus or the polycyclic erythematous scaly plaques of subacute cutaneous lupus help to distinguish these entities from CAD. Lupus may be further ruled out by checking ANA, anti-Ro, and anti-La antibodies.
Porphyrias should be considered in the evaluation of a photosensitive patient and can be ruled out with urine, blood and stool porphyrins. Mycosis fungoides is very rarely and only mildly photosensitive. Sezary syndrome should be considered with an erythrodermic presentation of CAD. Sezary cells can be identified in CAD, but there will typically be a lower CD4 to CD8 ratio than in Sezary syndrome.
In general, polymorphous light eruption (PMLE) tends to occur in younger patients and in discrete attacks, whereas CAD patients are older and with a baseline persistent eruption. Solar urticaria may present with papular lesions; however, compared to CAD, these papules are in the form of edematous wheals and often occur within minutes of sun exposure. A photoexacerbated drug eruption will typically appear more erythematous and edematous compared to the eczematous eruption of CAD, usually caused by UVA alone, and the history of drug exposure can be elicited.
Who is at Risk for Developing this Disease?
The patients most commonly affected by CAD are elderly men; however, women can also be affected. Younger patients more rarely develop CAD, and those that do often have a history of atopic dermatitis. CAD has been also reported to occur in patients with HIV infection; these patients are usually younger than the typical CAD patients.
CAD is seen in all skin types, although Fitzpatrick skin types V and VI are more commonly affected. CAD occurs worldwide, but occurs with greater frequency in temperate climates. Many patients have a previous history of atopic dermatitis and often have multiple contact allergies.
What is the Cause of the Disease?
It is speculated that CAD results from an endogenous cutaneous antigen that is activated by UV exposure, resulting in a process analogous to allergic contact dermatitis. Elderly patients with a history of chronic UV exposure may have an attenuation of the normal UV-induced cutaneous immune-suppression. As a result, they may be more likely to recognize and react to the antigen in CAD compared to younger patients who develop CAD less frequently. Patients with atopic dermatitis may be more prone to CAD because of their baseline immune hyperreactivity.
Systemic Implications and Complications
CAD is more common in patients infected with HIV and in some cases has been the presenting sign of HIV. Testing for HIV should be considered in CAD patients who have HIV risk factors. CAD does not appear to be associated with an increased risk of lymphoma, in spite of previous case reports describing the potential for lymphomatous transformation. Rare case reports describe a possible association with adult T-cell leukemia, but it is unclear whether this relationship is coincidental.
Treatment options are summarized in Table I.
|Medical Treatment||Surgical Procedures||Physical Modalities|
|Topical calcineurin inhibitors (tacrolimus ointment, pimecrolimus cream)||PUVA (+ oral corticosteroid)|
|Topical corticosteroids||PUVA (+ oral corticosteroid + mycophenolate mofetil)|
Optimal Therapeutic Approach for this Disease
Photoprotective measures are of primary importance in the treatment of CAD and should be used by all patients. Patients should use a broad spectrum sunscreen that provides protection against both UVB and UVA with a SPF at or above 30. This sunscreen should contain either avobenzone or emcamsule (Mexoryl SX), as these filters provide the most effective UVA protection currently available in the United States. Inorganic filters such as zinc oxide or titanium dioxide can also provide effective broad spectrum coverage, but frequently are less cosmetically elegant.
Additional measures such as seeking shade while outdoors, avoiding direct sun exposure during the peak UV hours (10 AM to 4 PM), the use of photoprotective clothing, and wearing a wide-brimmed hat should also be encouraged. As UVA can penetrate through window class, protective films can be used on car windows.
Most patients do not respond to photoprotection alone, especially when the eczematous lesions are longstanding. As such, topical therapies are often used in conjunction with photoprotective measures as the first line of treatment. Potent topical corticosteroids are often helpful due to the chronic lichenification.
Recent case reports and small studies describe tacrolimus ointment as an effective treatment in CAD. Long-term use of any medication in CAD is required due to the persistence of the disease. Tacrolimus ointment can be considered a reasonable first-line agent in place of topical corticosteroids, which have the disadvantage of cutaneous side effects after long term use.
Systemic therapies are the next line of treatment in CAD. Brief courses of oral prednisone (0.5-1.0mg/kg/day) may abort flares. In patients requiring longer durations of systemic treatment, azathioprine (1-2.5mg/kg/day) is often helpful as an initial oral agent. Mycophenolate mofetil (1-3g/day) could also be considered as a first-line oral therapy, as it has the advantage of a more favorable side effect profile.
Cyclosporine (2.5-5mg/kg/day) appears effective in CAD, but is limited by its side effect profile and the inability to use long term. Hydroxychloroquine and hydroxyurea may also be considered if the patient has not responded to other oral therapies.
Psoralen and UVA (PUVA) phototherapy can also be an effective treatment. Initially, oral corticosteroids are often required in conjunction with PUVA to prevent flaring of the CAD. Therapeutic success of a combination regimen of PUVA, oral corticosteroids and mycophenolate mofetil has also been reported.
Surgical procedures are not commonly used in the treatment of CAD, although the successful use of manual dermabrasion has been described in a single case report.
Patients need to be aware of the natural course of CAD. The disease resolves in 10% of patients after 5 years, 20% of patients after 10 years, and 50% of patients after 15 years. The prognosis is poorer in patients with severe sensitivity to UVB and/or coincident contact allergy. Since a significant number of CAD patients have coexisting contact sensitivities, identification of their contact allergens and appropriate treatment can be important.
CAD can have a significant impact on a patient’s quality of life, so treatment should be appropriately aggressive. Yet the risks of systemic treatment need to be weighted against the expected benefit, particularly as CAD is more likely to affect elderly individuals who are often on multiple medications and may have multiple comorbidities.
Unusual Clinical Scenarios to Consider in Patient Management
CAD is especially difficult to manage in rare patients with severe sensitivity to visible light. On occasion, these patients can react to artificial light sources, making it difficult to function at home and at work without flaring their CAD. Unfortunately, sunscreen protection against visible light is currently inadequate.
Zinc oxide and titanium dioxide are the sunscreens with the most effective protection from visible light, but a thick opaque coating is needed and in result is cosmetically displeasing. Protective clothing can be helpful, but it is clearly not practical to cover all exposed areas, such as the face.
What is the Evidence?
Hawk , JLM. “Chronic actinic dermatitis”. Photodermatol Photoimmunol Photomed . vol. 20. 2004. pp. 312-4. (An excellent review on all aspects of CAD, including clinical presentation and treatment options.)
Dawe , RS, Ferguson , J. “Diagnosis and treatment of chronic actinic dermatitis”. Dermatol Ther . vol. 16. 2003. pp. 45-51. (This article is another thorough overview of CAD, and includes an in-depth discussion of the pathophysiology of the disease.)
Lim , HW, Morison , WL, Kamide , R, Buchness , MR, Harris , R, Soter , NA. “Chronic actinic dermatitis: an analysis of 51 patients evaluated in the United States and Japan”. Arch Dermatol . vol. 130. 1994. pp. 1284-9. (This series of 51 patients provides important data on the phototesting profile of CAD patients, specifically with most patients being sensitive to both UVA and UVB. Fewer patients were sensitive to UVA alone and only one patient was sensitive to visible light. Classically, it was thought that virtually all patients with CAD were photosensitive to UVB, however in this study 29% of patients were not.)
Yap , LM, Foley , P, Crouch , R, Baker , C. “Chronic actinic dermatitis: a retrospective analysis of 44 cases referred to an Australian photobiology clinic”. Australas J Dermatol . vol. 44. 2003. pp. 256-62. (Thirty-six percent of patients improved with photoprotection, minimizing sun exposure and topical corticosteroids. However, the majority of patients (64%) required additional systemic therapies or phototherapy.)
Thomson , MA, Stewart , DG, Lewis , HM. “Chronic actinic dermatitis treated with mycophenolate mofetil”. Br J Dermatol. vol. 152. 2005. pp. 784-786. (Two patients improved within 6 weeks and then cleared on mycophenolate mofetil. Remission was maintained with 500 mg twice daily in one patient and 1000mg twice daily in the other, with the latter only requiring medication during the sunny portions of the year.)
Murphy , GM, Maurice , PD, Norris , PG, Morris , RW, Hawk , JL. Br J Dermatol . vol. 121. 1989. pp. 639-46. (Five of 8 patients receiving azathioprine 50mg/day experienced remission within 6 months of treatment, compared to 0 of 10 placebo patients.)
Uetso , N, Okamoto , H, Fujii , K, Doi , R, Horio , T. “Treatment of chronic actinic dermatitis with tacrolimus ointment”. J Amer Acad Dermatol . vol. 47. 2002. pp. 881-4. (Six patients trended toward improvement at 2 weeks and had significantly cleared their eruptions at 4 weeks. Several recent case reports and studies tout tacrolimus ointment as a promising topical treatment for CAD.)
Nousari , HC, Anhalt , GJ. “Mycophenolate in psoralen-UV-A desensitization therapy for chronic actinic dermatitis”. Arch Dermatol . vol. 135. 1999. pp. 1128-29. (Two patients remitted with a combination of mycophenolate mofetil, PUVA and oral prednisone. The addition of mycophenolate mofetil allowed for a lower prednisone dose (40mg/day) than was typically used. The authors of this study also noted that anecdotally the initial prednisone for CAD patients typically require higher doses of steroids, sometimes approaching 100mg/day.)
Menage H du , P, Ross , JS, Norris , PG, Hawk , JLM. “Contact and photocontact sensitization in chronic actinic dermatitis: sesquiterpene lactone mix is an important allergen”. Br J Dermatol . vol. 132. 1995. pp. 543-47. (Seventy-two percent of patients had positive patch tests and 11% had positive photopatch tests, underscoring the frequent comorbidity of contact dermatitis in CAD patients.)
Dawe , RS, Crombie , IK, Ferguson , J. “The natural history of chronic actinic dermatitis”. Arch Dermatol . vol. 136. 2000. pp. 1215-20. (This article allows the clinician to concretely communicate the prognosis of CAD with a patient. Photosensitivity resolved in 1 in 5 patients resolved by 5 years, 1 in 10 by 10 years, and 1 in 2 by 15 years.)
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